Bicalutamide, sold under the brand name Casodex among others, is an
antiandrogen
Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking the ...
medication that is primarily used to treat
prostate cancer.
It is typically used together with a
gonadotropin-releasing hormone (GnRH) analogue or
surgical removal of the testicles to treat
advanced prostate cancer.
To a lesser extent, it is used for early prostate cancer The Early Prostate Cancer (EPC) programme was a large clinical trial programme of monotherapy with the nonsteroidal antiandrogen bicalutamide (Casodex) plus standard care versus standard care alone in men with early prostate cancer. It was started i ...
at a higher dosage as a monotherapy without castration
Castration is any action, surgical, chemical, or otherwise, by which an individual loses use of the testicles: the male gonad. Surgical castration is bilateral orchiectomy (excision of both testicles), while chemical castration uses pharma ...
. Bicalutamide is also used to treat excessive hair growth and scalp hair loss in women, as a component of feminizing hormone therapy
Feminizing hormone therapy, also known as transfeminine hormone therapy, is hormone therapy and sex reassignment therapy to change the secondary sex characteristics of transgender people from masculine or androgynous to feminine. It is a co ...
for transgender women
A trans woman or a transgender woman is a woman who was assigned male at birth. Trans women have a female gender identity, may experience gender dysphoria, and may transition; this process commonly includes hormone replacement therapy and ...
, to treat early puberty
In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of childr ...
in boys, and to prevent overly long-lasting erections in men. It is taken by mouth
Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are i ...
.
Common side effects in men include breast enlargement Breast enlargement is the enlargement of the breasts. It may occur naturally as in mammoplasia or may occur artificially through active intervention. Many women regard their breasts, which are female secondary sex characteristics, as important to t ...
, breast tenderness
Breast pain is the symptom of discomfort in either one or both breasts. Pain in both breasts is often described as ''breast tenderness'', is usually associated with the menstrual period and is not serious. Pain that involves only one part of a br ...
, and hot flashes
Hot flashes (also known as hot flushes) are a form of flushing, often caused by the changing hormone levels that are characteristic of menopause. They are typically experienced as a feeling of intense heat with sweating and rapid heartbeat, and ...
. Other side effects in men include feminization
Feminization most commonly refers to:
* Feminization (biology), the hormonally induced development of female sexual characteristics
* Feminization (activity), a sexual or lifestyle practice where a person assumes a female role
* Feminization (soci ...
and sexual dysfunction
Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal sexual activity, including physical pleasure, desire, preference, arousal, or orgasm. The World Health Organization defines sexual dysfunction a ...
. Some side effects like breast changes and feminization are minimal when combined with castration. While the medication appears to produce few side effects in women, its use in cisgender women is not explicitly approved by the Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) at this time.[ Use during pregnancy may harm the baby.] Bicalutamide causes abnormal liver changes necessitating discontinuation in around 1% of people. Rarely, it has been associated with cases of liver damage
Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common.
Signs and symptoms
Some of the si ...
, lung toxicity, and sensitivity to light. Although the risk of adverse liver changes is small, monitoring of liver function is recommended during treatment.
Bicalutamide is a member of the nonsteroidal antiandrogen
A nonsteroidal antiandrogen (NSAA) is an antiandrogen with a nonsteroidal chemical structure. They are typically selective and full or silent antagonists of the androgen receptor (AR) and act by directly blocking the effects of androgens like ...
(NSAA) group of medications. It works by selectively blocking the androgen receptor (AR), the biological target
A biological target is anything within a living organism to which some other entity (like an endogenous ligand or a drug) is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets ...
of the androgen
An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
sex hormone
Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effect ...
s testosterone
Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
and dihydrotestosterone
Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous androgen sex steroid and hormone. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues includ ...
(DHT). It does not lower androgen levels. The medication can have some estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
-like effects in men when used as a monotherapy due to increased estradiol
Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development o ...
levels. Bicalutamide is well-absorbed, and its absorption is not affected by food. The elimination half-life
Biological half-life (also known as elimination half-life, pharmacologic half-life) is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration ( Cmax) to half of Cmax in the bl ...
of the medication is around one week. It shows peripheral selectivity in animals, but crosses the blood–brain barrier and affects both the body and brain in humans.
Bicalutamide was patented in 1982 and approved for medical use in 1995. It is on the World Health Organization's List of Essential Medicines
The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...
. Bicalutamide is available as a generic medication. The drug is sold in more than 80 countries, including most developed countries
A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
. It is the most widely used antiandrogen in the treatment of prostate cancer, and has been prescribed to millions of men with the disease.
Medical uses
Bicalutamide is approved for and mainly used in the following indications:
* Metastatic prostate cancer (mPC) in men in combination with a gonadotropin-releasing hormone
Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and release ...
(GnRH) analogue or surgical castration
Inguinal orchiectomy (also named orchidectomy) is a specific method of orchiectomy whereby one or both testicles and the full spermatic cord are surgically removed through an incision in the lower lateral abdomen (the "inguinal region"). The p ...
at 50 mg/day
* Locally advanced prostate cancer (LAPC) in men as a monotherapy at 150 mg/day (not approved for this use in the United States)
In Japan, bicalutamide is uniquely used at a dosage of 80 mg/day both in combination with castration and as a monotherapy in the treatment of prostate cancer.
Bicalutamide is also employed for the following off-label
Off-label use is the use of pharmaceutical drugs for an unapproved indication or in an unapproved age group, dosage, or route of administration. Both prescription drugs and over-the-counter drugs (OTCs) can be used in off-label ways, although ...
(non-approved) indications:
* To reduce the effects of the testosterone flare at the initiation of agonist therapy in men
* Androgen-dependent skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different de ...
and hair conditions such as acne
Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...
, seborrhea
A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest numbe ...
, excessive hair growth, and scalp hair loss in women as well as high testosterone levels due to polycystic ovary syndrome
Polycystic ovary syndrome, or PCOS, is the most common endocrine disorder in women of reproductive age. The syndrome is named after the characteristic cysts which may form on the ovaries, though it is important to note that this is a sign and no ...
(PCOS) in women, at 25 to 50 mg/day generally in combination with a birth control pill
The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control that is designed to be taken orally by women. The pill contains two important hormones: progesti ...
* Feminizing hormone therapy
Feminizing hormone therapy, also known as transfeminine hormone therapy, is hormone therapy and sex reassignment therapy to change the secondary sex characteristics of transgender people from masculine or androgynous to feminine. It is a co ...
for transgender women
A trans woman or a transgender woman is a woman who was assigned male at birth. Trans women have a female gender identity, may experience gender dysphoria, and may transition; this process commonly includes hormone replacement therapy and ...
in combination with an estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
usually at 50 mg/day
* Peripheral precocious puberty
In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of childr ...
in boys at 12.5 to 100 mg/day in combination with an aromatase inhibitor
Aromatase inhibitors (AIs) are a class of drugs used in the treatment of breast cancer in postmenopausal women and in men, and gynecomastia in men. They may also be used off-label to reduce estrogen conversion when supplementing testosterone ex ...
like anastrozole
Anastrozole, sold under the brand name Arimidex among others, is a medication used in addition to other treatments for breast cancer. Specifically it is used for hormone receptor-positive breast cancer. It has also been used to prevent breast ca ...
, especially for familial male-limited precocious puberty
Familial male-limited precocious puberty, often abbreviated as FMPP, also known as familial sexual precocity or gonadotropin-independent testotoxicosis, is a form of gonadotropin-independent precocious puberty in which boys experience early onset ...
(testotoxicosis)
* Overly long-lasting erections in men at 50 mg per week to 50 mg every other day
The medication has been suggested for but has uncertain effectiveness in the following indication:
* Hypersexuality
Hypersexuality is extremely frequent or suddenly increased libido. It is controversial whether it should be included as a clinical diagnosis used by mental healthcare professionals. Nymphomania and satyriasis were terms previously used for the c ...
and paraphilia
Paraphilia (previously known as sexual perversion and sexual deviation) is the experience of intense sexual arousal to atypical objects, situations, fantasies, behaviors, or individuals. It has also been defined as sexual interest in anything ot ...
s, particularly in combination with chemical castration
Chemical castration is castration via anaphrodisiac drugs, whether to reduce libido and sexual activity, to treat cancer, or otherwise. Unlike surgical castration, where the gonads are removed through an incision in the body,
For more information on these uses, see the medical uses of bicalutamide article.
Available forms
Bicalutamide is available for the treatment of prostate cancer in most developed countries, including over 80 countries worldwide. It is available in 50 mg, 80 mg (in Japan), and 150 mg tablets for oral administration
Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are ...
. The drug is registered for use as a 150 mg/day monotherapy for the treatment of in at least 55 countries, with the being a notable exception where it is registered only for use at a dosage of 50 mg/day in combination with castration. No other formulations
Formulation is a term used in various senses in various applications, both the material and the abstract or formal. Its fundamental meaning is the putting together of components in appropriate relationships or structures, according to a formul ...
or routes of administration
A route of administration in pharmacology and toxicology is the way by which a medication, drug, fluid, poison, or other substance is taken into the body.
Routes of administration are generally classified by the location at which the substance i ...
are available or used. All formulations of bicalutamide are specifically indicated for the treatment of prostate cancer alone or in combination with surgical or medication castration. A combined formulation of bicalutamide and the agonist goserelin
Goserelin, sold under the brand name Zoladex among others, is a medication which is used to suppress production of the sex hormones (testosterone and estrogen), particularly in the treatment of breast and prostate cancer. It is an injectable gon ...
in which goserelin is provided as a subcutaneous implant for injection
Injection or injected may refer to:
Science and technology
* Injective function, a mathematical function mapping distinct arguments to distinct values
* Injection (medicine), insertion of liquid into the body with a syringe
* Injection, in broadca ...
and bicalutamide is included as 50 mg tablets for oral ingestion is marketed in Australia and New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
under the brand name ZolaCos CP (Zoladex–Cosudex Combination Pack).
Contraindications
Bicalutamide is pregnancy category X, or "contraindicated in pregnancy", in the , and pregnancy category D, the second most restricted rating, in Australia. As such, it is contraindicated in women during pregnancy, and women who are sexually active and who can or may become pregnant are strongly recommended to take bicalutamide only in combination with adequate contraception
Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unwanted pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth contr ...
. It is unknown whether bicalutamide is excreted in breast milk, but many drugs are excreted in breast milk, and for this reason, bicalutamide treatment is similarly not recommended while breastfeeding
Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that br ...
.
In individuals with severe, though not mild-to-moderate hepatic impairment
Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common.
Signs and symptoms
Some of the sig ...
, there is evidence that the elimination of bicalutamide is slowed, and hence, caution may be warranted in these patients as circulating levels of bicalutamide may be increased. In severe hepatic impairment, the elimination half-life of the active (''R'')- enantiomer of bicalutamide is increased by about 1.75-fold (76% increase; elimination half-life of 5.9 and 10.4 days for normal and impaired patients, respectively). The elimination half-life of bicalutamide is unchanged in renal impairment
Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
.
Side effects
The side effect
In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...
profile of bicalutamide is highly dependent on sex; that is, on whether the person is male or female. In men, due to androgen deprivation, a variety of side effects of varying severity may occur during bicalutamide treatment, with breast pain/tenderness and gynecomastia
Gynecomastia (also spelled gynaecomastia) is the abnormal non-cancerous enlargement of one or both breasts in males due to the growth of breast tissue as a result of a hormone imbalance between estrogens and androgens. Updated by Brent Wisse ( ...
(breast development
Breast development, also known as mammogenesis, is a complex biological process in primates that takes place throughout a female's life.
It occurs across several phases, including prenatal development, puberty, and pregnancy. At menopause, bre ...
/ enlargement) being the most common. Gynecomastia occurs in up to 80% of men treated with bicalutamide monotherapy, though is of only mild-to-moderate severity in more than 90% of affected men. In addition to breast changes, physical feminization
Feminization most commonly refers to:
* Feminization (biology), the hormonally induced development of female sexual characteristics
* Feminization (activity), a sexual or lifestyle practice where a person assumes a female role
* Feminization (soci ...
and demasculinization
Virilization or masculinization is the biological development of adult male characteristics in young males or females. Most of the changes of virilization are produced by androgens.
Virilization is most commonly used in three medical and biology ...
in general, including reduced body hair growth, decreased muscle mass
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle ...
and strength
Strength may refer to:
Physical strength
*Physical strength, as in people or animals
* Hysterical strength, extreme strength occurring when people are in life-and-death situations
*Superhuman strength, great physical strength far above human c ...
, feminine changes in fat mass
Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...
and distribution Distribution may refer to:
Mathematics
*Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations
* Probability distribution, the probability of a particular value or value range of a vari ...
, reduced penile length, and decreased semen/ejaculate volume, may occur in men. Other side effects that have been observed in men and that are similarly related to androgen deprivation include hot flash
Hot flashes (also known as hot flushes) are a form of flushing, often caused by the changing hormone levels that are characteristic of menopause. They are typically experienced as a feeling of intense heat with sweating and rapid heartbeat, and ...
es, sexual dysfunction
Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal sexual activity, including physical pleasure, desire, preference, arousal, or orgasm. The World Health Organization defines sexual dysfunction a ...
(e.g., loss of libido
Libido (; colloquial: sex drive) is a person's overall sexual drive or desire for sexual activity. Libido is influenced by biological, psychological, and social factors. Biologically, the sex hormones and associated neurotransmitters that act u ...
, erectile dysfunction), depression, fatigue, weakness
Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, i ...
, and anemia
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...
. However, most men have preserved sexual function with bicalutamide monotherapy. In females, due to the minimal biological importance of androgens in this sex, the side effects of pure antiandrogens or are few, and bicalutamide has been found to be very well tolerated. General side effects of bicalutamide that may occur in either sex include diarrhea
Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...
, constipation
Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...
, abdominal pain
Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues.
Common causes of pain in the abdomen include gastroenteritis and irritable bowel syndrome. About 15% of people have a m ...
, nausea
Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
, dry skin
Xeroderma, xerosis or xerosis cutis, or simply dry skin, is a skin condition characterized by excessively dry skin.
The medical term ''xeroderma'', meaning "dry skin", derives from modern Latin, ''xero-'' 'dry' + Greek ''derma'' 'skin'.
In most ...
, itching
Itch (also known as pruritus) is a Wikt:sensation, sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of Sensory system, sensory experience. Itch has many similarities to pain, ...
, and rash
A rash is a change of the human skin which affects its color, appearance, or texture.
A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, c ...
. The drug is well-tolerated at higher dosages than 50 mg/day, with rare additional side effects.
Bicalutamide has been associated with abnormal liver function tests
Liver function tests (LFTs or LFs), also referred to as a hepatic panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin ti ...
such as elevated liver enzymes
In medicine, the presence of elevated transaminases, commonly the transaminases alanine transaminase (ALT) and aspartate transaminase (AST), may be an indicator of liver dysfunction. Other terms include transaminasemia, transaminitis, and elevated ...
. In the Early Prostate Cancer The Early Prostate Cancer (EPC) programme was a large clinical trial programme of monotherapy with the nonsteroidal antiandrogen bicalutamide (Casodex) plus standard care versus standard care alone in men with early prostate cancer. It was started i ...
(EPC) clinical programme of bicalutamide for early prostate cancer The Early Prostate Cancer (EPC) programme was a large clinical trial programme of monotherapy with the nonsteroidal antiandrogen bicalutamide (Casodex) plus standard care versus standard care alone in men with early prostate cancer. It was started i ...
, the rate of abnormal liver function tests with bicalutamide monotherapy was 3.4% relative to 1.9% for placebo
A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures.
In general, placebos can af ...
. Hepatic
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it is ...
changes that have necessitated discontinuation of bicalutamide, such as marked increases in liver enzymes or hepatitis
Hepatitis is inflammation of the liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes ( jaundice), poor appetite, vomiting, tiredness, abdominal ...
, have occurred in approximately 0.3 to 1.4% of men in clinical trials. Elevated liver enzymes with bicalutamide usually occur within the first 3 to 6 months of treatment. Monitoring of liver function during treatment is recommended, particularly in the first few months. In men of advanced age with prostate cancer, bicalutamide monotherapy has been associated with an increase in non-prostate cancer mortality, in part due to an increase in the rate of heart failure. These mortality-related effects are thought to be a consequence of androgen deprivation, rather than due to a specific drug-related toxicity of bicalutamide.
There are 10 published case report In medicine, a case report is a detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient. Case reports may contain a demographic profile of the patient, but usually describe an unusual or novel occurrenc ...
s of liver toxicity associated with bicalutamide as of 2021. Death occurred in 2 of these cases. In all reported cases, the onset of toxicity was within the first 6 months of treatment. Symptoms that may indicate liver dysfunction
Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common.
Signs and symptoms
Some of the s ...
include nausea, vomiting, abdominal pain, fatigue, anorexia
Anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. ''Anorexia'' is a term of Gre ...
, "flu-like" symptoms, dark urine, and jaundice. There are also published case reports of interstitial pneumonitis
Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue and space around the alveoli (air sacs)) of the lungs. It concerns alveolar epithelium, pu ...
and eosinophilic lung disease associated with bicalutamide. Interstitial pneumonitis can potentially progress to pulmonary fibrosis
Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failu ...
and may be fatal. Symptoms that may indicate lung dysfunction include dyspnea
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...
(difficult breathing or shortness of breath), cough, and pharyngitis
Pharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a Rhinorrhea, runny nose, cough, headache, difficulty swallowing, swollen lymph nodes, and a ...
(inflammation
Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
of the pharynx
The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its st ...
, resulting in sore throat
Sore throat, also known as throat pain, is pain or irritation of the throat. Usually, causes of sore throat include
* viral infections
* group A streptococcal infection (GAS) bacterial infection
* pharyngitis (inflammation of the throat)
* to ...
). Both hepatotoxicity and interstitial pneumonitis are said to be very rare events with bicalutamide. A few cases of photosensitivity Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicit ...
have been reported with bicalutamide. Hypersensitivity reaction
Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune s ...
s ( drug allergy) like angioedema
Angioedema is an area of swelling (edema) of the lower layer of skin and tissue just under the skin or mucous membranes. The swelling may occur in the face, tongue, larynx, abdomen, or arms and legs. Often it is associated with hives, which are ...
and hives have also uncommonly been reported in association with bicalutamide.
Because it is an antiandrogen, bicalutamide has a theoretical risk of birth defect
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities ca ...
s like ambiguous genitalia
Intersex people are individuals born with any of several sex characteristics including chromosome patterns, gonads, or genitals that, according to the Office of the United Nations High Commissioner for Human Rights, "do not fit typical bin ...
and brain feminization in male fetus
A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...
es. Due to its teratogenic capacity, contraception
Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unwanted pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth contr ...
should be used in women taking bicalutamide who are fertile and sexually active.
Comparison
The side effect profile of bicalutamide in men and women differs from that of other antiandrogens and is considered favorable in comparison. Relative to analogues and the steroidal antiandrogen (SAA) cyproterone acetate
Cyproterone acetate (CPA), sold alone under the brand name Androcur or with ethinylestradiol under the brand names Diane or Diane-35 among others, is an antiandrogen and progestin medication used in the treatment of androgen-dependent condition ...
(CPA), bicalutamide monotherapy has a much lower incidence and severity of hot flashes and sexual dysfunction. In addition, unlike analogues and , bicalutamide monotherapy is not associated with decreased bone mineral density or osteoporosis. Conversely, bicalutamide monotherapy is associated with much higher rates of breast tenderness, gynecomastia, and feminization in men than analogues and . However, gynecomastia with bicalutamide is rarely severe and discontinuation rates due to this side effect are fairly low. These differences in side effects between bicalutamide monotherapy, analogues, and are attributed to the fact that whereas analogues and suppress estrogen production, bicalutamide monotherapy does not lower estrogen levels and in fact actually increases them.
Bicalutamide does not share the risk of neuropsychiatric
Neuropsychiatry or Organic Psychiatry is a branch of medicine that deals with psychiatry as it relates to neurology, in an effort to understand and attribute behavior to the interaction of neurobiology and social psychology factors. Within neurop ...
side effects like depression and fatigue as well as cardiovascular
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
side effects like coagulation
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanis ...
changes, blood clot
A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of ...
s, fluid retention, ischemic cardiomyopathy, and adverse serum lipid
Blood lipids (or blood fats) are lipids in the blood, either free or bound to other molecules. They are mostly transported in a protein capsule, and the density of the lipids and type of protein determines the fate of the particle and its influen ...
changes that has been associated with. It has a much lower risk of hepatotoxicity than flutamide
Flutamide, sold under the brand name Eulexin among others, is a nonsteroidal antiandrogen (NSAA) which is used primarily to treat prostate cancer. It is also used in the treatment of androgen-dependent conditions like acne, excessive hair grow ...
and and of interstitial pneumonitis than nilutamide
Nilutamide, sold under the brand names Nilandron and Anandron, is a nonsteroidal antiandrogen (NSAA) which is used in the treatment of prostate cancer.https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/020169s008lbl.pdf It has also been ...
. The drug also does not share the unique risks of diarrhea with flutamide and nausea, vomiting, visual disturbances, and alcohol intolerance
Alcohol intolerance is due to a genetic polymorphism of the aldehyde dehydrogenase enzyme, which is responsible for the metabolism of acetaldehyde (produced from the metabolism of alcohol by alcohol dehydrogenase). This polymorphism is most often r ...
with nilutamide. Unlike enzalutamide
Enzalutamide, sold under the brand name Xtandi, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is indicated for use in conjunction with castration in the treatment of metastatic castrat ...
, bicalutamide is not associated with seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
s or related central side effects like anxiety and insomnia
Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...
. However, although the risk of adverse liver changes with bicalutamide is low, enzalutamide differs from bicalutamide in having no known risk of elevated liver enzymes or hepatotoxicity. In contrast to the spironolactone
Spironolactone, sold under the brand name Aldactone among others, is a medication that is primarily used to treat fluid build-up due to heart failure, liver scarring, or kidney disease. It is also used in the treatment of high blood press ...
, bicalutamide does not have antimineralocorticoid
An antimineralocorticoid, also known as a mineralocorticoid receptor antagonist (MRA or MCRA) or aldosterone antagonist, is a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is ofte ...
effects, and hence is not associated with hyperkalemia
Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0mmol/L (3.5 and 5.0mEq/L) with levels above 5.5mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occasi ...
, urinary frequency
Frequent urination, or urinary frequency (sometimes called pollakiuria), is the need to urinate more often than usual. Diuretics are medications that increase urinary frequency. Nocturia is the need of frequent urination at night. The most common c ...
, dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
, hypotension
Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...
, or other related side effects. In women, unlike and spironolactone, bicalutamide does not produce menstrual irregularity
Irregular menstruation is a menstrual disorder whose manifestations include irregular cycle lengths as well as metrorrhagia (vaginal bleeding between expected periods). The possible causes of irregular menstruation may vary. The common factors of ...
or amenorrhea
Amenorrhea is the absence of a menstrual period in a woman of reproductive age. Physiological states of amenorrhoea are seen, most commonly, during pregnancy and lactation (breastfeeding). Outside the reproductive years, there is absence of menses ...
and does not interfere with ovulation
Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilize ...
or fertility
Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...
.
Overdose
A single oral dose of bicalutamide in humans that results in symptoms of overdose or that is considered to be life-threatening has not been established. Dosages of up to 600 mg/day have been well tolerated in clinical trials, and it is notable that there is a saturation of absorption with bicalutamide such that circulating levels of its active (''R'')-enantiomer do not further increase above a dosage of 300 mg/day. Overdose is considered unlikely to be life-threatening with bicalutamide or other first-generation (i.e., flutamide and nilutamide). A massive overdose of nilutamide (13 grams, or 43 times the normal maximum 300 mg/day clinical dosage) in a 79-year-old man was uneventful, producing no clinical signs, symptoms, or toxicity. There is no specific antidote
An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are s ...
for bicalutamide or overdose, and treatment should be based on symptoms, if any are present.
Interactions
Bicalutamide is almost exclusively metabolized
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
by CYP3A4. As such, its levels in the body may be altered by inhibitors and inducers of CYP3A4. (For a list of CYP3A4 inhibitors and inducers, see here
Here is an adverb that means "in, on, or at this place". It may also refer to:
Software
* Here Technologies, a mapping company
* Here WeGo (formerly Here Maps), a mobile app and map website by Here Technologies, Here
Television
* Here TV (form ...
.) However, in spite of the fact bicalutamide is metabolized by CYP3A4, there is no evidence of clinically significant drug interaction
Drug interactions occur when a drug's mechanism of action is disturbed by the concomitant administration of substances such as foods, beverages, or other drugs. The cause is often the inhibition of the specific receptors available to the drug, ...
s when bicalutamide at a dosage of 150 mg/day or less is co-administered with drugs that inhibit or induce cytochrome P450
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
activity.
''In-vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology and ...
'' studies suggest that bicalutamide may be able to inhibit CYP3A4 and, to a lesser extent, CYP2C9
Cytochrome P450 family 2 subfamily C member 9 (abbreviated CYP2C9) is an enzyme protein. The enzyme is involved in metabolism, by oxidation, of both xenobiotics, including drugs, and endogenous compounds, including fatty acids. In humans, the prote ...
, CYP2C19
Cytochrome P450 2C19 (abbreviated CYP2C19) is an enzyme protein. It is a member of the CYP2C subfamily of the cytochrome P450 mixed-function oxidase system. This subfamily includes enzymes that catalyze metabolism of xenobiotics, including some p ...
, and CYP2D6
Cytochrome P450 2D6 (CYP2D6) is an enzyme that in humans is encoded by the ''CYP2D6'' gene. ''CYP2D6'' is primarily expressed in the liver. It is also highly expressed in areas of the central nervous system, including the substantia nigra.
CYP2D ...
. Conversely, animal studies suggest that bicalutamide may induce cytochrome P450 enzymes. In a clinical study, bicalutamide co-administered with the CYP3A4 substrate midazolam caused only a small and statistically non-significant increase in midazolam levels (+27%) presumably due to CYP3A4 inhibition. However, this was well below increases in midazolam exposure with potent CYP3A4 inhibitors like ketoconazole (+1500%), itraconazole
Itraconazole, sometimes abbreviated ITZ, is an antifungal medication used to treat a number of fungal infections. This includes aspergillosis, blastomycosis, coccidioidomycosis, histoplasmosis, and paracoccidioidomycosis. It may be given by mo ...
(+1000%), and erythromycin (+350%), and is considered to not be clinically important. There is no indication of clinically significant enzyme inhibition or induction with bicalutamide at doses of 150mg/day or below.
Because bicalutamide circulates at relatively high concentrations and is highly protein-bound, it has the potential to displace other highly protein-bound drugs like warfarin
Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent st ...
, phenytoin
Phenytoin (PHT), sold under the brand name Dilantin among others, is an anti-seizure medication. It is useful for the prevention of tonic-clonic seizures (also known as grand mal seizures) and focal seizures, but not absence seizures. The in ...
, theophylline
Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the ...
, and aspirin
Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat inc ...
from plasma binding proteins. This could, in turn, result in increased free concentrations of such drugs and increased effects and/or side effects, potentially necessitating dosage adjustments. Bicalutamide has specifically been found to displace coumarin
Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered h ...
anticoagulants like warfarin from their plasma binding proteins (namely albumin
Albumin is a family of globular proteins, the most common of which are the serum albumins. All the proteins of the albumin family are water-soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Albumins ...
) ''in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology ...
'', potentially resulting in an increased anticoagulant effect, and for this reason, close monitoring of prothrombin
Thrombin (, ''fibrinogenase'', ''thrombase'', ''thrombofort'', ''topical'', ''thrombin-C'', ''tropostasin'', ''activated blood-coagulation factor II'', ''blood-coagulation factor IIa'', ''factor IIa'', ''E thrombin'', ''beta-thrombin'', ''gamma- ...
time and dosage adjustment as necessary is recommended when bicalutamide is used in combination with these drugs. However, in spite of this, no conclusive evidence of an interaction between bicalutamide and other drugs was found in clinical trials of nearly 3,000 patients.
Pharmacology
Pharmacodynamics
Antiandrogenic activity
Bicalutamide acts as a highly selective competitive
Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...
silent antagonist
A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist. Antagonist drugs interfere in the natural operation of recep ...
of the ( = 159–243 nM), the major biological target
A biological target is anything within a living organism to which some other entity (like an endogenous ligand or a drug) is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets ...
of the androgen
An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This in ...
sex hormone
Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effect ...
s testosterone
Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
and , and hence is an antiandrogen
Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking the ...
. The activity of bicalutamide lies in the (''R'')-isomer. Due to its selectivity for the , bicalutamide does not interact importantly with other steroid hormone receptor
Steroid hormone receptors are found in the nucleus, cytosol, and also on the plasma membrane of target cells. They are generally intracellular receptors (typically cytoplasmic or nuclear) and initiate signal transduction for steroid hormones which ...
s and hence has no clinically relevant off-target hormonal activity (e.g., progestogenic, estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
ic, glucocorticoid
Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...
, antimineralocorticoid
An antimineralocorticoid, also known as a mineralocorticoid receptor antagonist (MRA or MCRA) or aldosterone antagonist, is a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is ofte ...
). However, it has been reported that bicalutamide has weak affinity for the progesterone receptor (PR), where it is an antagonist, and hence it could have some antiprogestogen
Antiprogestogens, or antiprogestins, also known as progesterone antagonists or progesterone blockers, are a class of drugs which prevent progestogens like progesterone from mediating their biological effects in the body. They act by blocking the ...
ic activity. Bicalutamide does not inhibit
Inhibitor or inhibition may refer to:
In biology
* Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity
* Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotr ...
5α-reductase nor is known to inhibit other enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s involved in androgen steroidogenesis
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...
(e.g., CYP17A1
Cytochrome P450 17A1 (steroid 17α-monooxygenase, 17α-hydroxylase, 17-alpha-hydroxylase, 17,20-lyase, 17,20-desmolase) is an enzyme of the hydroxylase type that in humans is encoded by the ''CYP17A1'' gene on chromosome 10. It is ubiquitously exp ...
). Although it does not bind to the estrogen receptor
Estrogen receptors (ERs) are a group of proteins found inside cells. They are receptors that are activated by the hormone estrogen (17β-estradiol). Two classes of ER exist: nuclear estrogen receptors ( ERα and ERβ), which are members of the ...
s (ERs), bicalutamide can increase estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
levels secondarily to blockade when used as a monotherapy in males, and hence can have some ''indirect'' estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...
ic effects in males. Bicalutamide neither suppresses nor inhibits androgen production
Production may refer to:
Economics and business
* Production (economics)
* Production, the act of manufacturing goods
* Production, in the outline of industrial organization, the act of making products (goods and services)
* Production as a stati ...
in the body (i.e., it does not act as an antigonadotropin
An antigonadotropin is a drug which suppresses the activity and/or downstream effects of one or both of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This results in an inhibition of the hypothalamic-pitui ...
or androgen steroidogenesis inhibitor or lower androgen levels) and hence exclusively mediates its antiandrogenic effects by antagonizing the . In addition to the classical nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
*Nuclear space
*Nuclear ...
, bicalutamide has been assessed at the membrane androgen receptor Membrane androgen receptors (mARs) are a group of G protein-coupled receptors (GPCRs) which bind and are activated by testosterone and/or other androgens. Unlike the androgen receptor (AR), a nuclear receptor which mediates its effects via genomic m ...
s (mARs) and found to act as a potent antagonist of ZIP9
Zinc transporter ZIP9, also known as Zrt- and Irt-like protein 9 (ZIP9) and solute carrier family 39 member 9, is a protein that in humans is encoded by the ''SLC39A9'' gene. This protein is the 9th member out of 14 ZIP family proteins, which is ...
( = 66.3 nM), whereas it does not appear to interact with GPRC6A
G protein-coupled receptor family C group 6 member A (GPRC6A) is a protein that in humans is encoded by the ''GPRC6A'' gene. This protein functions as a receptor of L-α-amino acids, cations (e.g., calcium), osteocalcin, and steroids. It is a me ...
.
The affinity
Affinity may refer to:
Commerce, finance and law
* Affinity (law), kinship by marriage
* Affinity analysis, a market research and business management technique
* Affinity Credit Union, a Saskatchewan-based credit union
* Affinity Equity Par ...
of bicalutamide for the is relatively low as it is approximately 30 to 100 times lower than that of , which is 2.5- to 10-fold as potent as an agonist as testosterone in bioassay
A bioassay is an analytical method to determine the concentration or potency of a substance by its effect on living animals or plants (''in vivo''), or on living cells or tissues(''in vitro''). A bioassay can be either quantal or quantitative, dir ...
s and is the main endogenous ligand
In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...
of the receptor
Receptor may refer to:
* Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse
*Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ...
in the prostate gland
The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and physio ...
. However, typical clinical dosages of bicalutamide result in circulating levels of the drug that are thousands of times higher than those of testosterone and , allowing it to powerfully prevent them from binding to and activating the receptor. This is especially true in the case of surgical or medical castration, in which testosterone levels in the circulation are approximately 95% reduced and levels in the prostate gland are about 50 to 60% reduced. In women, levels of testosterone are substantially lower (20- to 40-fold) than in men, so much smaller doses of bicalutamide (e.g., 25 mg/day in the hirsutism studies) are necessary.
Blockade of the by bicalutamide in the pituitary gland
In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland, about the size of a chickpea and weighing, on average, in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The ...
and hypothalamus
The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
results in prevention of the negative feedback of androgens on the hypothalamic–pituitary–gonadal axis
The hypothalamic–pituitary–gonadal axis (HPG axis, also known as the hypothalamic–pituitary–ovarian/testicular axis) refers to the hypothalamus, pituitary gland, and gonadal glands as if these individual endocrine glands were a single en ...
(HPG axis) in males and consequent disinhibition of pituitary luteinizing hormone
Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...
(LH) secretion. This, in turn, results in an increase in circulating levels and activation of the gonadal production of testosterone and by extension production of estradiol
Estradiol (E2), also spelled oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of the estrous and menstrual female reproductive cycles. Estradiol is responsible for the development o ...
. Levels of testosterone have been found to increase 1.5- to 2-fold (59–97% increase) and levels of estradiol about 1.5- to 2.5-fold (65–146% increase) in men treated with 150 mg/day bicalutamide monotherapy. In addition to testosterone and estradiol, there are smaller increases in concentrations of , sex hormone-binding globulin
Sex hormone-binding globulin (SHBG) or sex steroid-binding globulin (SSBG) is a glycoprotein that binds to androgens and estrogens. When produced by the Sertoli cells in the seminiferous tubules of the testis, it has also been called androgen ...
, and prolactin
Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...
. Estradiol levels with bicalutamide monotherapy are similar to those in the low-normal premenopausal
Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often d ...
female range while testosterone levels generally remain in the high end of the normal male range. Testosterone concentrations do not typically exceed the normal male range due to negative feedback on the axis by the increased concentrations of estradiol. Bicalutamide influences the axis and increases hormone levels only in men and not also in women. This is due to the much lower levels of androgens in women and their lack of basal suppression of the axis in this sex. As evidenced by its effectiveness in the treatment of prostate cancer and other androgen-dependent conditions, the antiandrogenic actions of bicalutamide considerably exceed any impact of the increased levels of testosterone it results in. However, the elevated levels of estradiol remain unopposed by bicalutamide and are responsible for the gynecomastia and feminizing side effects it causes in men. Although bicalutamide monotherapy increases gonadotropin and sex hormone levels in men, this will not occur if bicalutamide is combined with an antigonadotropin such as a analogue, estrogen, or progestogen, as these medications maintain negative feedback on the HPG axis.
monotherapy, including with bicalutamide, shows a number of tolerability differences from methods of androgen deprivation therapy that incorporate surgical or medical castration. For example, the rates of hot flashes, depression, fatigue, and sexual dysfunction are all much higher with analogues than with monotherapy. It is thought that this is because analogues suppress estrogen production in addition to androgen production, resulting in estrogen deficiency
Hypoestrogenism, or estrogen deficiency, refers to a lower than normal level of estrogen. It is an umbrella term used to describe estrogen deficiency in various conditions. Estrogen deficiency is also associated with an increased risk of cardiov ...
. In contrast, monotherapy does not decrease estrogen levels and in fact increases them, resulting in an excess of estrogens that compensates for androgen deficiency and allows for a preservation of mood, energy, and sexual function. Neurosteroids that are produced from testosterone like 3α-androstanediol and 3β-androstanediol
3β-Androstanediol, also known as 5α-androstane-3β,17β-diol, and sometimes shortened in the literature to 3β-diol, is an endogenous steroid hormone and a metabolite of androgens like dehydroepiandrosterone (DHEA) and dihydrotestosterone (DHT) ...
, which are agonists and the former a potent GABAA receptor positive allosteric modulator
In pharmacology and biochemistry, allosteric modulators are a group of substances that bind to a receptor to change that receptor's response to stimulus. Some of them, like benzodiazepines, are drugs. The site that an allosteric modulator binds to ...
, may also be involved. In the specific case of sexual dysfunction, an additional possibility for the difference is that without concomitant suppression of androgen production, blockade of the by the bicalutamide in the brain is incomplete and insufficient to markedly influence sexual function.
Under normal circumstances, bicalutamide has no capacity to activate the . However, in prostate cancer, mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA replication, DNA or viral repl ...
s and overexpression of the can accumulate in prostate gland cells which can convert bicalutamide from an antagonist of the into an agonist. This can result in paradoxical stimulation of prostate cancer growth with bicalutamide and is responsible for the phenomenon of the antiandrogen withdrawal syndrome, where antiandrogen discontinuation paradoxically slows the rate of prostate cancer growth.
In transgender women, breast development is a desired effect of antiandrogen or estrogen treatment. Breast development and gynecomastia induced by bicalutamide is thought to be mediated by increased activation of the secondary to blockade of the (resulting in disinhibition of the in breast tissue) and increased levels of estradiol. In addition to fat deposition, connective tissue growth, and ductal
Lafarge is a French industrial company specialising in cement, construction aggregates, and concrete. It is the world's largest cement manufacturer. It was founded in 1833 by Joseph-Auguste Pavin de Lafarge and is a part of the Holcim Group.
...
development, bicalutamide has been found to produce moderate lobuloalveolar development of the breasts. However, full lobuloalveolar maturation necessary for lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The proces ...
and breastfeeding
Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that br ...
will not occur without progestogen treatment.
Bicalutamide monotherapy seems to have minimal effect on testicular
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testosteron ...
spermatogenesis, testicular ultrastructure
Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a co ...
, and certain aspects of male fertility
Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertilit ...
. This seems to be because testosterone levels in the testes (where ≈95% of testosterone in males is produced) are extremely high (up to 200-fold higher than circulating levels) and only a small fraction (less than 10%) of the normal levels of testosterone in the testes are actually necessary to maintain spermatogenesis. As a result, bicalutamide appears to not be able to compete with testosterone in this sole part of the body to an extent sufficient to considerably interfere with androgen signaling and function. However, while bicalutamide does not seem to be able to adversely influence testicular spermatogenesis, it may interfere with -dependent sperm maturation and transport outside of the testes in the epididymides and vas deferens
The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube ...
where androgen levels are far lower, and hence may still be able to impair male fertility. In addition, the combination of bicalutamide with other medications, such as estrogens, progestogens, and analogues, can compromise spermatogenesis due to their own adverse effects on male fertility. These medications are able to strongly suppress gonadal androgen production, which can severely impair or abolish testicular spermatogenesis, and estrogens also appear to have direct and potentially long-lasting cytotoxic effects in the testes at sufficiently high concentrations.
Other activities
Bicalutamide has been found to act as an inhibitor or inducer
In molecular biology, an inducer is a molecule that regulates gene expression. An inducer functions in two ways; namely:
*By disabling repressors. The gene is expressed because an inducer binds to the repressor. The binding of the inducer to the r ...
of certain cytochrome P450
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s including CYP3A4, CYP2C9
Cytochrome P450 family 2 subfamily C member 9 (abbreviated CYP2C9) is an enzyme protein. The enzyme is involved in metabolism, by oxidation, of both xenobiotics, including drugs, and endogenous compounds, including fatty acids. In humans, the prote ...
, CYP2C19
Cytochrome P450 2C19 (abbreviated CYP2C19) is an enzyme protein. It is a member of the CYP2C subfamily of the cytochrome P450 mixed-function oxidase system. This subfamily includes enzymes that catalyze metabolism of xenobiotics, including some p ...
, and CYP2D6
Cytochrome P450 2D6 (CYP2D6) is an enzyme that in humans is encoded by the ''CYP2D6'' gene. ''CYP2D6'' is primarily expressed in the liver. It is also highly expressed in areas of the central nervous system, including the substantia nigra.
CYP2D ...
in preclinical research
In drug development, preclinical development, also termed preclinical studies or nonclinical studies, is a stage of research that begins before clinical trials (testing in humans) and during which important feasibility, iterative testing and drug ...
, but no evidence of this has been found in humans treated with up to 150 mg/day. It has also been identified ''in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology ...
'' as a strong inhibitor of CYP27A1
CYP27A1 is a gene encoding a cytochrome P450 oxidase, and is commonly known as sterol 27-hydroxylase. This enzyme is located in many different tissues where it is found within the mitochondria. It is most prominently involved in the biosynthesi ...
(cholesterol 27-hydroxylase) and as an inhibitor of CYP46A1
Cholesterol 24-hydroxylase (), also commonly known as cholesterol 24S-hydroxylase, cholesterol 24-monooxygenase, CYP46, or CYP46A1, is an enzyme that catalysis, catalyzes the conversion of cholesterol to 24S-hydroxycholesterol. It is responsible ...
(cholesterol 24-hydroxylase), but this has yet to be assessed or confirmed ''in vivo
Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...
'' or in humans and the clinical significance remains unknown. Bicalutamide has been found to be a P-glycoprotein (ABCB1) inhibitor. Like other first-generation and enzalutamide
Enzalutamide, sold under the brand name Xtandi, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is indicated for use in conjunction with castration in the treatment of metastatic castrat ...
, it has been found to act as a weak non-competitive inhibitor of GABAA receptor-mediated current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
s ''in vitro'' ( = 5.2 μM). However, unlike enzalutamide, bicalutamide has not been found to be associated with seizure
An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
s or other related adverse central effects, so the clinical relevance of this finding is uncertain.
Pharmacokinetics
Though its absolute bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation.
By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...
in humans is unknown, bicalutamide is known to be extensively and well- absorbed. Its absorption is not affected by food. The absorption of bicalutamide is linear at doses up to 150 mg/day and is saturable at doses above this, with no further increases in steady-state levels of bicalutamide occurring at doses above 300 mg/day. Whereas absorption of (''R'')-bicalutamide is slow, with levels peak Peak or The Peak may refer to:
Basic meanings Geology
* Mountain peak
** Pyramidal peak, a mountaintop that has been sculpted by erosion to form a point Mathematics
* Peak hour or rush hour, in traffic congestion
* Peak (geometry), an (''n''-3)-di ...
ing at 31 to 39 hours after a dose, (''S'')-bicalutamide is much more rapidly absorbed. Steady-state concentrations of the drug are reached after 4 to 12 weeks of treatment independently of dosage, with a 10- to 20-fold progressive accumulation in levels of (''R'')-bicalutamide. The long time to steady-state levels is the result of bicalutamide's very long elimination half-life
Biological half-life (also known as elimination half-life, pharmacologic half-life) is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration ( Cmax) to half of Cmax in the bl ...
.
The tissue distribution of bicalutamide is not well-characterized. The amount of bicalutamide in semen
Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Sem ...
that could potentially be transferred to a female partner during sexual intercourse is low and is not thought to be important. Based on animal studies
Animal studies is a recently recognised field in which animals are studied in a variety of cross-disciplinary ways. Scholars who engage in animal studies may be formally trained in a number of diverse fields, including geography, art history, ant ...
with rats and dogs it was thought that bicalutamide could not cross the blood–brain barrier and hence could not enter the brain. As such, it was initially thought to be a peripherally selective Peripherally selective drugs have their primary mechanism of action outside of the central nervous system (CNS), usually because they are excluded from the CNS by the blood–brain barrier. By being excluded from the CNS, drugs may act on the rest ...
antiandrogen. However, subsequent clinical studies found that this was not also the case for humans, indicating species differences; bicalutamide crosses into the human brain and, in accordance, produces effects and side effects consistent with central antiandrogenic action. Bicalutamide is highly plasma protein bound (96.1% for racemic bicalutamide, 99.6% for (''R'')-bicalutamide) and is bound mainly to albumin
Albumin is a family of globular proteins, the most common of which are the serum albumins. All the proteins of the albumin family are water-soluble, moderately soluble in concentrated salt solutions, and experience heat denaturation. Albumins ...
, with negligible binding to and corticosteroid-binding globulin
Transcortin, also known as corticosteroid-binding globulin (CBG) or serpin A6, is a protein produced in the liver in animals. In humans it is encoded by the SERPINA6 gene. It is an alpha-globulin.
Function
This gene encodes an alpha-globulin p ...
.
Bicalutamide is metabolized
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
in the liver
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
. (''R'')-Bicalutamide is metabolized slowly and almost exclusively via hydroxylation by CYP3A4 into (''R'')-hydroxybicalutamide. This metabolite is then glucuronidated
Glucuronidation is often involved in drug metabolism of substances such as drugs, pollutants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids, and bile acids. These linkages involve glycosid ...
by UGT1A9
UDP-glucuronosyltransferase 1-9 is an enzyme that in humans is encoded by the ''UGT1A9'' gene.
Function
This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such a ...
. In contrast to (''R'')-bicalutamide, (''S'')-bicalutamide is metabolized rapidly and mainly by glucuronidation (without hydroxylation). None of the metabolites of bicalutamide are known to be active and levels of the metabolites are low in plasma, where unchanged biclautamide predominates. Due to the stereoselective metabolism of bicalutamide, (''R'')-bicalutamide has a far longer terminal half-life than (''S'')-bicalutamide and its levels are about 10- to 20-fold higher in comparison following a single dose and 100-fold higher at steady-state. (''R'')-Bicalutamide has a relatively long elimination half-life of 5.8 days with a single dose and 7 to 10 days following repeated administration.
Bicalutamide is eliminated in similar proportions in feces (43%) and urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellular ...
(34%), while its metabolites are eliminated roughly equally in urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellular ...
and bile. The drug is excreted
Excretion is a process in which metabolic waste
is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after lea ...
to a substantial extent in unmetabolized form, and both bicalutamide and its metabolites are eliminated mainly as glucuronide
A glucuronide, also known as glucuronoside, is any substance produced by linking glucuronic acid to another substance via a glycosidic bond. The glucuronides belong to the glycosides.
Glucuronidation, the conversion of chemical compounds to glucu ...
conjugates. The glucuronide conjugates of bicalutamide and its metabolites are eliminated from the circulation rapidly, unlike unconjugated bicalutamide.
The pharmacokinetics of bicalutamide are not affected by consumption of food, a person's age or body weight, renal impairment
Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
, or mild-to-moderate hepatic impairment
Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common.
Signs and symptoms
Some of the sig ...
. However, steady-state levels of bicalutamide are higher in Japanese individuals than in white people
White is a racialized classification of people and a skin color specifier, generally used for people of European origin, although the definition can vary depending on context, nationality, and point of view.
Description of populations as ...
.
Chemistry
Bicalutamide is a racemic mixture consisting of equal proportions of enantiomers (''R'')-bicalutamide (dextrorotatory
Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...
) and (''S'')-bicalutamide (levorotatory
Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...
). Its systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature.
A semisystematic name or semitrivial ...
( ) is (''RS'')-''N''- -cyano-3-(trifluoromethyl)phenyl3- 4-fluorophenyl)sulfonyl2-hydroxy-2-methylpropanamide. The compound has a chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...
of C18H14F4N2O4S, a molecular weight
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
of 430.373 g/mol, and is a fine white to off-white powder.
The acid dissociation constant (pKa') of bicalutamide is approximately 12. It is a highly lipophilic
Lipophilicity (from Greek λίπος "fat" and φίλος "friendly"), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such non-polar solvents are themselves lipo ...
compound ( log P = 2.92). At 37 °C (98.6 °F), or normal human body temperature
Normal human body-temperature (normothermia, euthermia) is the typical temperature range found in humans. The normal human body temperature range is typically stated as .
Human body temperature varies. It depends on sex, age, time of day, exert ...
, bicalutamide is practically insoluble
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution.
The extent of the solubil ...
in water (4.6 mg/L), acid (4.6 mg/L at pH 1), and alkali (3.7 mg/L at pH 8). In organic solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
s, it is slightly soluble in chloroform and absolute ethanol, sparingly soluble in methanol, and freely soluble in acetone
Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour.
Acetone is miscib ...
and tetrahydrofuran
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
.
Bicalutamide is a synthetic and nonsteroidal A nonsteroidal compound is a drug that is not a steroid nor a steroid derivative. Nonsteroidal anti-inflammatory drugs (NSAIDs) are distinguished from corticosteroids as a class of anti-inflammatory agents.
List of nonsteroidal steroid receptor mo ...
compound
Compound may refer to:
Architecture and built environments
* Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall
** Compound (fortification), a version of the above fortified with defensive struc ...
which was derived
Derive may refer to:
* Derive (computer algebra system), a commercial system made by Texas Instruments
* ''Dérive'' (magazine), an Austrian science magazine on urbanism
*Dérive, a psychogeographical concept
See also
*
*Derivation (disambiguatio ...
from flutamide
Flutamide, sold under the brand name Eulexin among others, is a nonsteroidal antiandrogen (NSAA) which is used primarily to treat prostate cancer. It is also used in the treatment of androgen-dependent conditions like acne, excessive hair grow ...
. It is a bicyclic compound (has two ring
Ring may refer to:
* Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry
* To make a sound with a bell, and the sound made by a bell
:(hence) to initiate a telephone connection
Arts, entertainment and media Film and ...
s) and can be classified as and has variously been referred to as an anilide
Anilides (or phenylamides) are a class of chemical compounds, which are amide derivatives of aniline.
Preparation
Aniline reacts with acyl chlorides or carboxylic anhydrides to give anilides. For example, reaction of aniline with acetyl chlorid ...
(''N''-phenyl
In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6 H5, and is often represented by the symbol Ph. Phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen ...
amide
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it i ...
) or aniline
Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...
, a diaryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
propionamide, and a toluidide.
Analogues
First-generation including bicalutamide, flutamide
Flutamide, sold under the brand name Eulexin among others, is a nonsteroidal antiandrogen (NSAA) which is used primarily to treat prostate cancer. It is also used in the treatment of androgen-dependent conditions like acne, excessive hair grow ...
, and nilutamide
Nilutamide, sold under the brand names Nilandron and Anandron, is a nonsteroidal antiandrogen (NSAA) which is used in the treatment of prostate cancer.https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/020169s008lbl.pdf It has also been ...
are all synthetic, nonsteroidal anilide derivatives and structural analog
A structural analog (analogue in modern traditional English; Commonwealth English), also known as a chemical analog or simply an analog, is a compound having a structure similar to that of another compound, but differing from it in respect to a c ...
ues of each other. Bicalutamide is a diarylpropionamide while flutamide is a monoarylpropionamide and nilutamide is a hydantoin. Bicalutamide and flutamide, though not nilutamide, can also be classified as toluidides. All three of the compounds share a common 3-trifluoromethyl
The trifluoromethyl group is a functional group that has the formula -CF3. The naming of is group is derived from the methyl group (which has the formula -CH3), by replacing each hydrogen atom by a fluorine atom. Some common examples are trifluoro ...
aniline
Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...
moiety. Bicalutamide is a modification of flutamide in which a 4-fluoro
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely react ...
phenyl
In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6 H5, and is often represented by the symbol Ph. Phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen ...
sulfonyl
In organosulfur chemistry, a sulfonyl group can refer either to a functional group found primarily in sulfones, or to a substituent obtained from a sulfonic acid by the removal of the hydroxyl group, similarly to acyl groups. Sulfonyl groups c ...
moiety has been added and the nitro group on the original phenyl ring has been replaced with a cyano group. Topilutamide
Topilutamide, known more commonly as fluridil and sold under the brand name Eucapil, is an antiandrogen medication which is used in the treatment of pattern hair loss in men and women. It is used as a topical medication and is applied to the sc ...
, also known as fluridil, is another that is closely related structurally to the first-generation , but, in contrast to them, is not used in the treatment of prostate cancer and is instead used exclusively as a topical
A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes ...
antiandrogen in the treatment of pattern hair loss.
The second-generation enzalutamide and apalutamide
Apalutamide, sold under the brand name Erleada among others, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is specifically indicated for use in conjunction with castration in the treatme ...
were derived from and are analogues of the first-generation , while another second-generation , darolutamide
Darolutamide, sold under the brand name Nubeqa, is an antiandrogen medication which is used in the treatment of non-metastatic castration-resistant prostate cancer in men. It is specifically approved to treat non-metastatic castration-resista ...
, is said to be structurally distinct and chemically unrelated to the other . Enzalutamide is a modification of bicalutamide in which the inter-ring linking chain has been altered and cyclized into a 5,5-di methyl-4- oxo-2-thioxo
The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ''ether,'' referring to an oxy ...
imidazolidine
Imidazolidine is a heterocyclic compound (CH2)2(NH)2CH2. The parent imidazolidine is lightly studied, but related compounds substituted on one or both nitrogen centers are more common. Generally, they are colorless, polar, basic compounds. Imida ...
moiety. In apalutamide, the 5,5-dimethyl groups of the imidazolidine ring of enzalutamide are cyclized to form an accessory cyclobutane
Cyclobutane is a cycloalkane and organic compound with the formula (CH2)4. Cyclobutane is a colourless gas and commercially available as a liquefied gas. Derivatives of cyclobutane are called cyclobutanes. Cyclobutane itself is of no commercia ...
ring and one of its phenyl rings is replaced with a pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a ...
ring.
The first nonsteroidal androgens, the arylpropionamides, were discovered via structural modification of bicalutamide. Unlike bicalutamide (which is purely antiandrogenic), these compounds show tissue-selective androgenic effects and were classified as selective androgen receptor modulator
Selective Androgen Receptor Modulators or SARMs are a class of androgen receptor ligands that maintain some of the desirable effects of androgens, such as preventing osteoporosis and muscle loss while reducing risks of developing prostate cance ...
s (SARMs). Lead of this series included acetothiolutamide
Acetothiolutamide is a selective androgen receptor modulator (SARM) derived from the nonsteroidal antiandrogen bicalutamide that was described in 2002 and was one of the first SARMs to be discovered and developed. It is a high-affinity, selective ...
, enobosarm
Enobosarm, also known as ostarine or MK-2866, is an investigational selective androgen receptor modulator (SARM) developed by GTx, Inc. for the treatment of conditions such as muscle wasting and osteoporosis, formerly under development by Merc ...
(ostarine; S-22), and andarine
Andarine (developmental code names GTx-007, S-4) is an investigational selective androgen receptor modulator (SARM) developed by GTX, Inc for treatment of conditions such as muscle wasting, osteoporosis and benign prostatic hypertrophy, using th ...
(acetamidoxolutamide or androxolutamide; S-4). They are very close to bicalutamide structurally, with the key differences being that the linker sulfone of bicalutamide has been replaced with an ether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...
or thioether
In organic chemistry, an organic sulfide (British English sulphide) or thioether is an organosulfur functional group with the connectivity as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A su ...
group to confer agonism of the and the 4-fluoro atom of the pertinent phenyl ring has been substituted with an acetamido or cyano group to eliminate reactivity at the position.
A few radiolabeled
A radioactive tracer, radiotracer, or radioactive label is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tr ...
derivatives of bicalutamide have been developed for potential use as radiotracer
A radioactive tracer, radiotracer, or radioactive label is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tr ...
s in medical imaging. They include 18F">sup>18Ficalutamide, 4- 76Br">sup>76Brromobicalutamide, and 76Br">sup>76Brromo-thiobicalutamide. The latter two were found to have substantially increased affinity for the relative to that of bicautamide. However, none of these agents have been evaluated in humans.
5''N''-Bicalutamide, or 5-azabicalutamide, is a minor structural modification of bicalutamide which acts as a reversible covalent antagonist of the and has approximately 150-fold higher affinity for the and about 20-fold greater functional inhibition of the relative to bicalutamide.[Pamela, M., Fletterick, R. J., Kuchenbecker, K., & de Jesus Cortez, F. (2016). U.S. Patent Application No. 15/382,942. https://www.google.com/patents/US20170101384] It is among the most potent antagonists to have been developed and is being researched for potential use in the treatment of antiandrogen-resistant prostate cancer.
Synthesis
A number of chemical syntheses of bicalutamide have been published in the literature. The procedure of the first published synthesis of bicalutamide can be seen below.
History
Bicalutamide as well as all of the other currently marketed were derived from structural modification of flutamide, which itself was originally synthesized as a bacteriostatic agent in 1967 at Schering Plough Corporation and was subsequently and serendipitously found to possess antiandrogenic activity. Bicalutamide was discovered by Tucker and colleagues at Imperial Chemical Industries (ICI) in the 1980s and was selected for development from a group of over 2,000 synthesized compounds. It was first patented in 1982 and was first reported in the scientific literature
: ''For a broader class of literature, see Academic publishing.''
Scientific literature comprises scholarly publications that report original empirical and theoretical work in the natural and social sciences. Within an academic field, scie ...
in June 1987.
Bicalutamide was first studied in a phase I clinical trial
Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, diet ...
in 1987 and the results of the first phase II clinical trial in prostate cancer were published in 1990. The pharmaceutical division of was split out into an independent company called Zeneca
Zeneca (officially Zeneca Group PLC) was a British multinational pharmaceutical company headquartered in London, United Kingdom. It was formed in June 1993 by the demerger of the pharmaceuticals and agrochemicals businesses of Imperial Che ...
in 1993, and in April and May 1995, Zeneca (now AstraZeneca
AstraZeneca plc () is a British-Swedish multinational pharmaceutical and biotechnology company with its headquarters at the Cambridge Biomedical Campus in Cambridge, England. It has a portfolio of products for major diseases in areas includi ...
, after merging with Astra AB in 1999) began pre-approval marketing of bicalutamide for the treatment of prostate cancer in the . It was first launched in the in May 1995, and was subsequently approved by the on 4 October 1995, for the treatment of prostate cancer at a dosage of 50 mg/day in combination with a analogue.
Following its introduction for use in combination with a analogue, bicalutamide was developed as a monotherapy at a dosage of 150 mg/day for the treatment of prostate cancer, and was approved for this indication in Europe, Canada, and a number of other countries in the late 1990s and early 2000s. This application of bicalutamide was also under review by the in the in 2002, but ultimately was not approved in this country. In Japan, bicalutamide is licensed at a dosage of 80 mg/day alone or in combination with a analogue for prostate cancer. The unique 80 mg dosage of bicalutamide used in Japan was selected for development in this country on the basis of observed pharmacokinetic differences with bicalutamide in Japanese men.
Subsequent to negative findings of bicalutamide monotherapy for in the clinical programme, approval of bicalutamide for use specifically in the treatment of was withdrawn in a number of countries including the (in October or November 2003) and several other European countries and Canada (in August 2003). In addition, the and Canada explicitly recommended against the use of 150 mg/day bicalutamide for this indication. The drug is effective for, remains approved for, and continues to be used in the treatment of and , on the other hand.
The patent protection of bicalutamide expired in the in March 2009 and the drug has subsequently been available as a generic, at greatly reduced cost.
Bicalutamide was the fourth antiandrogen (and the third ) to be introduced for the treatment of prostate cancer, following the in 1973 and the flutamide in 1983 (1989 in the ) and nilutamide in 1989 (1996 in the ). It has been followed by abiraterone acetate
Abiraterone acetate, sold under the brand name Zytiga among others, is a medication used to treat prostate cancer. Specifically it is used together with a corticosteroid for metastasis, metastatic Prostate cancer#Castration-resistant cancer, ca ...
in 2011, enzalutamide in 2012, apalutamide in 2018, and darolutamide in 2019, and may also be followed by in-development drugs such as proxalutamide
Proxalutamide (developmental code name GT-0918) is a nonsteroidal antiandrogen (NSAA) – specifically, a selective high-affinity silent antagonist of the androgen receptor (AR) – which is under development by Suzhou Kintor Pharmaceuticals, ...
and seviteronel
__NOTOC__
Seviteronel (developmental codes VT-464 and, formerly, INO-464) is an experimental cancer medication which is under development by Viamet Pharmaceuticals and Innocrin Pharmaceuticals for the treatment of prostate cancer and breast canc ...
.
Society and culture
Generic names
''Bicalutamide'' is the generic name of the drug in English and French and its , , , , , , and . It is also referred to as ''bicalutamidum'' in Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, ''bicalutamida'' in Spanish and Portuguese
Portuguese may refer to:
* anything of, from, or related to the country and nation of Portugal
** Portuguese cuisine, traditional foods
** Portuguese language, a Romance language
*** Portuguese dialects, variants of the Portuguese language
** Portu ...
, ''bicalutamid'' in German, and ''bikalutamid'' in Russian and other Slavic languages
The Slavic languages, also known as the Slavonic languages, are Indo-European languages spoken primarily by the Slavic peoples and their descendants. They are thought to descend from a proto-language called Proto-Slavic, spoken during the ...
. The "bica-" prefix corresponds to the fact that bicalutamide is a ''bicyclic'' compound, while the "-lutamide" suffix is the standard suffix for . Bicalutamide is also known by its former developmental code name -176,334.
Brand names
Bicalutamide is marketed by AstraZeneca in oral tablet form under the brand names Casodex, Cosudex, Calutide, Calumid, and Kalumid in many countries. It is also marketed under the brand names Bicadex, Bical, Bicalox, Bicamide, Bicatlon, Bicusan, Binabic, Bypro, Calutol, and Ormandyl among others in various countries. The drug is sold under a large number of generic trade names such as Apo-Bicalutamide, Bicalutamide Accord, Bicalutamide Actavis, Bicalutamide Bluefish, Bicalutamide Kabi, Bicalutamide Sandoz, and Bicalutamide Teva as well. A combination formulation of bicalutamide and goserelin is marketed by AstraZeneca in Australia and New Zealand under the brand name ZolaCos-CP.
Cost and generics
Bicalutamide is off-patent and available as a generic. Unlike bicalutamide, the newer enzalutamide is still on-patent, and for this reason, is considerably more expensive in comparison.
The patent protection
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
of all three of the first-generation has expired and flutamide and bicalutamide are both available as low-cost generics. Nilutamide, on the other hand, has always been a poor third competitor to flutamide and bicalutamide and, in relation to this fact, has not been developed as a generic and is only available as brand name Nilandron, at least in the
Bicalutamide is considerably less costly than analogues, which, in spite of some having been off-patent many years, have been reported (in 2013) to typically cost –$15,000 per year (or about per month) of treatment.
Sales and usage
Sales of bicalutamide (as Casodex) worldwide peaked at US$
The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
1.3 billion in 2007, and it has been described as a "billion-dollar-a-year" drug prior to losing its patent protection starting in 2007. In 2014, despite the introduction of abiraterone acetate in 2011 and enzalutamide in 2012, bicalutamide was still the most commonly prescribed drug in the treatment of metastatic castration-resistant prostate cancer (mCRPC). Moreover, in spite of being off-patent, bicalutamide was said to still generate a few hundred million dollars in sales per year for AstraZeneca. Total worldwide sales of brand name Casodex were approximately US$
The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
13.4 billion as of the end of 2018.
Between January 2007 and December 2009 (a period of three years), 1,232,143 prescriptions of bicalutamide were dispensed in the , or about 400,000 prescriptions per year. During that time, bicalutamide accounted for about 87.2% of the market, while flutamide accounted for 10.5% of it and nilutamide for 2.3% of it. Approximately 96% of bicalutamide prescriptions were written for diagnosis codes that clearly indicated neoplasm
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
. About 1,200, or 0.1% of bicalutamide prescriptions were dispensed to pediatric patients (age 0–16).
Regulation
Bicalutamide is a prescription drug. It is not specifically a controlled substance
A controlled substance is generally a drug or chemical whose manufacture, possession and use is regulated by a government, such as illicitly used drugs or prescription medications that are designated by law. Some treaties, notably the Single ...
in any country and therefore is not an illegal drug
The prohibition of drugs through sumptuary legislation or religious law is a common means of attempting to prevent the recreational use of certain intoxicating substances.
While some drugs are illegal to possess, many governments regulate the ...
. However, the manufacture, sale, distribution Distribution may refer to:
Mathematics
*Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations
* Probability distribution, the probability of a particular value or value range of a vari ...
, and possession
Possession may refer to:
Law
* Dependent territory, an area of land over which another country exercises sovereignty, but which does not have the full right of participation in that country's governance
* Drug possession, a crime
* Ownership
* ...
of prescription drugs are all still subject to legal regulation throughout the world.
Research
Bicalutamide has been studied in combination with the 5α-reductase inhibitor
5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes of ...
s finasteride and dutasteride
Dutasteride, sold under the brand name Avodart among others, is a medication primarily used to treat the symptoms of a benign prostatic hyperplasia (BPH), an enlarged prostate not associated with cancer. A few months may be required before benefi ...
in prostate cancer. It has also been studied in combination with raloxifene
Raloxifene, sold under the brand name Evista among others, is a medication used to prevent and treat osteoporosis in postmenopausal women and those on glucocorticoids. For osteoporosis it is less preferred than bisphosphonates. It is also used to ...
, a selective estrogen receptor modulator (SERM), for the treatment of prostate cancer. Bicalutamide has been tested for the treatment of -positive /-negative locally advanced and metastatic breast cancer
Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumors, secondaries or stage IV breast cancer, is a stage of breast cancer where the breast cancer cells have spread to distant sites beyond the axillary l ...
in women in a phase II study for this indication. Enzalutamide is also being investigated for this type of cancer. Bicalutamide has also been studied in a phase II clinical trial for ovarian cancer
Ovarian cancer is a cancerous tumor of an ovary. It may originate from the ovary itself or more commonly from communicating nearby structures such as fallopian tubes or the inner lining of the abdomen. The ovary is made up of three different c ...
in women.
Bicalutamide has been studied in the treatment of benign prostatic hyperplasia
Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...
(BPH) in a 24-week trial of 15 patients at a dosage of 50 mg/day. Prostate volume decreased by 26% in patients taking bicalutamide and urinary irritative symptom scores significantly decreased. Conversely, peak urine flow rates and urine pressure flow examinations were not significantly different between bicalutamide and placebo. The decrease in prostate volume achieved with bicalutamide was comparable to that observed with the 5α-reductase inhibitor finasteride, which is approved for the treatment of BPH. Breast tenderness (93%), gynecomastia (54%), and sexual dysfunction (60%) were all reported as side effects of bicalutamide at the dosage used in the study, although no treatment discontinuations due to adverse effects occurred and sexual functioning was maintained in 75% of patients.
A phase III clinical trial of bicalutamide in combination with an ethinylestradiol
Ethinylestradiol (EE) is an estrogen medication which is used widely in birth control pills in combination with progestins. In the past, EE was widely used for various indications such as the treatment of menopausal symptoms, gynecological disord ...
-containing combined oral contraceptive
The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control that is designed to be taken orally by women. The pill contains two important hormones: progesti ...
for the treatment of severe hirsutism in women with was completed in Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
in 2017 under supervision of the Italian Agency for Drugs (AIFA).
Antiandrogens have been suggested for treating COVID-19
Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019. The disease quickly ...
in men and as of May 2020 high-dose bicalutamide is in a phase II clinical trial for this purpose.
Veterinary use
Bicalutamide may be used to treat hyperandrogenism and associated benign prostatic hyperplasia secondary to hyperadrenocorticism
Cushing's syndrome is a collection of signs and symptoms due to prolonged exposure to glucocorticoids such as cortisol. Signs and symptoms may include high blood pressure, abdominal obesity but with thin arms and legs, reddish stretch marks, ...
(caused by excessive adrenal androgens) in male ferrets. However, it has not been formally assessed in controlled studies for this purpose.
See also
* Comparison of bicalutamide with other antiandrogens
References
Further reading
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External links
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