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Finasteride, sold under the brand names Proscar and Propecia among others, is a medication used to treat
hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, ...
and
benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the . Symptoms may include frequent urination, trouble starting to urinate, weak stream, , or . Complications can include s, s, and . ...

benign prostatic hyperplasia
in men. It can also be used to treat excessive hair growth in women and as a part of
hormone therapy Hormone therapy or hormonal therapy is the use of hormones in medical treatment. Treatment with hormone antagonists may also be referred to as hormonal therapy or antihormone therapy. The most general classes of hormone therapy are hormonal therap ...
for
transgender women A trans woman is a woman who was assigned male at birth. Trans women may experience gender dysphoria and may transition; this process commonly includes hormone replacement therapy and sometimes sex reassignment surgery Sex reassignment surg ...
. It is taken
by mouth Oral administration is a route of administration Route or routes may refer to: * Route (gridiron football), a path run by a wide receiver * route (command), a program used to configure the routing table * Route, County Antrim, an area in No ...

by mouth
. Finasteride is a 5α-reductase inhibitor and therefore an
antiandrogen Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drug File:Aspirine macro shot.jpg, Uncoated aspirin Tablet (pharmacy), tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount o ...
. It works by decreasing the
production Production may be: 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 statistic, g ...

production
of
dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous Endogenous substances and processes are those that originate from within a system such as an organism, Tissue (biology), tissue, or Cell ...
(DHT) by about 70%, including 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 ...
and the
scalp The scalp is the anatomical area bordered by the human face The face is the front of an animal's head that features the eyes Eyes are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on ...
. In addition to DHT, finasteride also inhibits the production of several anticonvulsant neurosteroids including allopregnanolone, androstanediol and THDOC.
Adverse effects An adverse effect is an undesired harmful effect resulting from a medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to medical diagnosis, diagnose, cure, therapy, t ...
from finasteride are rare, however some men experience
sexual dysfunction Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal Human sexual activity, sexual activity, including physical pleasure, Sexual desire, desire, preference, sexual arousal, arousal, or orgasm. The Wor ...
,
depression Depression may refer to: Mental health * Depression (mood), a state of low mood and aversion to activity * Mood disorders characterized by depression are commonly referred to as simply ''depression'', including: ** Dysthymia ** Major depressive ...
, and
breast enlargementBreast enlargement is the enlargement of the breast The breast is one of two prominences located on the upper ventral region of the torso of primates. In females, it serves as the mammary gland, which produces and secretes milk to feed infan ...

breast enlargement
. In some men, sexual dysfunction may persist after stopping the medication. It may also hide the early symptoms of certain forms of
prostate cancer Prostate cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most o ...

prostate cancer
. Finasteride was patented in 1984 and approved for medical use in 1992. It is available as a
generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...
. In 2019, it was the 86th most commonly prescribed medication in the United States, with more than 8million prescriptions.


Medical uses

Finasteride is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate and for the treatment of male pattern hair loss (androgenetic alopecia) in men.


Enlarged prostate

Physicians sometimes prescribe finasteride for the treatment of benign prostatic hyperplasia (BPH), informally known as an enlarged
prostate The prostate is both an accessory gland of the male reproductive system The male reproductive system consists of a number of sex organ A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual repr ...

prostate
. Finasteride may improve the symptoms associated with BPH such as difficulty urinating, getting up during the night to urinate, hesitation at the start and end of urination, and decreased urinary flow. It provides less symptomatic relief than alpha-1 blockers such as
tamsulosin Tamsulosin, sold under the brand name Flomax among others, is a medication used to treat symptomatic benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the ...

tamsulosin
and symptomatic relief is slower in onset (six months or more of treatment with finasteride may be required to determine the therapeutic results of treatment). Symptomatic benefits are mainly seen in those with prostate volume > 40 cm3. In long-term studies finasteride but not alpha-1 inhibitors reduce the risk of acute urinary retention (−57% at 4 years) and the need for surgery (−54% at 4 years). If the drug is discontinued, any therapeutic benefits are reversed within about 6–8 months.


Scalp hair loss

Finasteride is also used to treat
male pattern baldness Pattern hair loss is hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including th ...
(androgenic alopecia) in men, a condition that develops in up to 80% of Caucasian men. In the United States, finasteride and
minoxidil Minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide), sold under the brand name Rogaine among others, is a medication used for the treatment of Hypertension, high blood pressure and male-pattern hair loss, pattern hair loss in males and females ...

minoxidil
are the only two FDA approved drugs for the treatment of male pattern hair loss as of 2017. Treatment with finasteride slows further hair loss and provides about 30% improvement in hair loss after six months of treatment, with effectiveness persisting as long as the drug is taken. Taking finasteride leads to a reduction in scalp and serum DHT levels; by lowering scalp levels of DHT, finasteride can maintain or increase the amount of terminal hairs in the by inhibiting and sometimes reversing miniaturization of the hair follicle. Finasteride is most effective on the
crown '' File:서봉총 금관 금제드리개.jpg, The Seobongchong Golden Crown of Ancient Silla, which is 339th National Treasure of South Korea. It is basically following the standard type of Silla's Crown. It was excavated by Swedish Crown Pri ...
but can reduce hair loss in all areas of the scalp. Finasteride has also been tested for pattern hair loss in women; however, the results were no better than placebo. Finasteride is less effective in the treatment of scalp hair loss than
dutasteride Dutasteride, sold under the brand name Avodart among others, is a medication composed of the molecular ingredients Dutasteride, dissolved in a mixture of mono-di-glycerides of caprylic/capric acid, and butylated hydroxytoluene, primarily used to ...

dutasteride
.


Prostate cancer

In males over 55 years old finasteride decreases the risk of low-grade
prostate cancer Prostate cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most o ...

prostate cancer
but may increase the risk of high-grade prostate cancer and has no effect on overall survival. A 2010 review found a 25% reduction in the risk of prostate cancer with 5α-reductase inhibitor. A follow-up study of the Medicare claims of participants in a 10-year Prostate Cancer Prevention Trial suggests the reduction in prostate cancer is maintained even after discontinuation of treatment. However, 5α-reductase inhibitors have been found to increase the risk of developing certain rare but aggressive forms of prostate cancer (27% risk increase), although not all studies have observed this. No impact of 5-α-reductase inhibitor on survival has been found in people with prostate cancer.


Excessive hair growth

Finasteride has been found to be effective in the treatment of
hirsutism Hirsutism is excessive body hair on parts of the body where hair is normally absent or minimal. The word is from early 17th century: from Latin ''hirsutus'' meaning "hairy". It may refer to a "male" pattern of hair growth that may be a sign of a ...
(excessive facial and/or body hair growth) in women. In a study of 89 women with
hyperandrogenism Hyperandrogenism is a medical condition A disease is a particular abnormal condition that negatively affects the structure A structure is an arrangement and organization of interrelated elements in a material object or system A ...
due to persistent adrenarche syndrome, finasteride produced a 93% reduction in facial hirsutism and a 73% reduction bodily hirsutism after 2 years of treatment. Other studies using finasteride for hirsutism have also found it to be clearly effective.


Transgender hormone therapy

Finasteride is sometimes used in
hormone replacement therapy Hormone replacement therapy (HRT), also known as menopausal hormone therapy or postmenopausal hormone therapy, is a form of hormone therapy used to treat menopausal symptoms, symptoms associated with female menopause. These symptoms can include ho ...
for
transgender women A trans woman is a woman who was assigned male at birth. Trans women may experience gender dysphoria and may transition; this process commonly includes hormone replacement therapy and sometimes sex reassignment surgery Sex reassignment surg ...
due to its
antiandrogen Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drug File:Aspirine macro shot.jpg, Uncoated aspirin Tablet (pharmacy), tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount o ...
ic effects, in combination with a form of
estrogen Estrogens or oestrogens, are a class of natural or synthetic s responsible for the development and regulation of the female and s. There are three major estrogens that have estrogenic hormonal activity: (E1), (E2), and (E3). Estradiol, an ...
. However, little
clinical research Clinical research is a branch of healthcare science The following outline is provided as an overview of and topical guide to health sciences: Health sciences – are those sciences which focus on health Health is a state of physical ...

clinical research
of finasteride use for this purpose has been conducted and evidence of safety or efficacy is limited. Moreover, caution has been recommended when prescribing finasteride to transgender women, as finasteride may be associated with side effects such as depression, anxiety, and suicidal ideation, symptoms that are particularly prevalent in the transgender population and in others at high risk already.


Adverse effects

A 2010 Cochrane review of finasteride for BPH found that, in men with a weighted mean age of 62.4, adverse effects are "rare; nevertheless, men taking finasteride are at increased risk for impotence, erectile dysfunction, decreased libido, and ejaculation disorder, versus placebo." fresh evidence suggested such effects, along with disturbed
neurosteroidNeurosteroids, also known as neuroactive steroids, are endogenous or exogenous steroid , a steroid with 27 carbon atoms. Its core ring system (ABCD), composed of 17 carbon atoms, is shown with IUPAC The International Union of Pure and Applie ...
production, may persist after finasteride use is stopped. Finasteride is contraindicated in pregnancy. The
Food and Drug Administration The United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, st ...
advises that donation of blood or plasma be deferred for at least one month after taking the last dose of finasteride. The FDA has added a warning to 5α-reductase inhibitors concerning an increased risk of high-grade
prostate cancer Prostate cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most o ...

prostate cancer
, as the treatment of BPH lowers PSA (
prostate-specific antigen Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related protease, peptidase family and is ...
), which could mask the development of prostate cancer. Although overall incidence of male breast cancer in clinical trials for finasteride 5 mg was not increased, there are post-marketing reports of breast cancer in association with its use, though available evidence does not provide clarity as to whether there is a causative relationship between finasteride and these cancers. A 2018
meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple Randomized controlled trial, scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each i ...
found no higher risk of breast cancer with 5α-reductase inhibitors. Some men develop
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 The breast is one of two prominences located on the upper ventral Standard anatomica ...

gynecomastia
(breast development or enlargement) following finasteride usage. The risk of gynecomastia with 5α-reductase inhibitors is low at about 1.5%. Depressive symptoms and suicidality have been reported.


Sexual adverse effects

Use of finasteride is associated with an increased risk of
sexual dysfunction Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal Human sexual activity, sexual activity, including physical pleasure, Sexual desire, desire, preference, sexual arousal, arousal, or orgasm. The Wor ...
including
erectile dysfunction Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal Human sexual activity, sexual activity, including physical ...

erectile dysfunction
, decreased libido and ejaculatory dysfunction. Sexual adverse effects of finasteride and dutasteride have been linked to lower
quality of life Quality of life (QOL) is defined by the World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United N ...

quality of life
and ability to maintain an intimate relationship, and can cause stress in relationships. The adverse effect profiles of finasteride are somewhat different for its indications of hair loss and BPH.


Finasteride for androgenetic alopecia (hair loss in men)

The most common adverse effects of finasteride taken for hair loss are: decrease in sex drive, erectile dysfunction and decrease in amount of semen. In addition, finasteride has been reported in
case reportsIn medicine Medicine is the Art (skill), art, science, and Praxis (process) , practice of caring for a patient and managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment or Palliative care , palliation of their inj ...
to cause sexual problems which persist after stopping the medication. A 2012 update to the FDA label noted reports of decreased sex drive, problems with ejaculation and difficulty achieving an erection which continued after stopping the medication. The update also referenced reports of testicular pain and "male infertility and/or poor quality of semen."


Finasteride for BPH

The most common adverse sexual effects of finasteride for BPH are: trouble getting or keeping an erection, decrease in sex drive, decreased volume of ejaculate and ejaculation disorders. A 2010 Cochrane review found that men taking finasteride for BPH (with a mean age of 62.4) are at increased risk for impotence, erectile dysfunction, decreased libido, and ejaculation disorder for the first year of treatment. The rates became indistinguishable from placebo after 2–4 years and these side effects usually got better over time.


Long-term

Finasteride may cause persistent adverse sexual, neurological and physical effects in a subset of men. A 2019 metastudy surveyed the literature on the reversibility of finasteride's side effects. It identified three studies which demonstrated full reversibility of side effects and eleven that describe patients with irreversible adverse events. The findings were most convincing in a retrospective review of about 12,000 patients that 1.4% of the cohort developed persistent ED.


Post-finasteride syndrome

Men in the U.S. and Canada concerned about persistent sexual side effects "coined the phrase 'post-finasteride syndrome', which they say is characterized by sexual, neurological, hormonal and psychological side effects that can persist in men who have taken finasteride for hair loss or an enlarged prostate". As of 2016, Merck was a defendant in approximately 1,370
product liability Product liability is the area of law Law is a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its envir ...
lawsuits which had been filed by customers alleging they have experienced persistent sexual side effects following cessation of treatment with finasteride. A 2019 editorial in ''
The BMJ ''The BMJ'' is a weekly peer-reviewed Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work ( peers). It functions as a form of self-regulation by qualified members of a profes ...
'' called post finasteride syndrome "ill defined and controversial". It has common features with other self-diagnosed "mystery syndromes" such as morgellons syndrome or multiple chemical sensitivity. There is no known underlying biological mechanism for the proposed syndrome, and its incidence is also unclear. A lack of clear diagnostic criteria and the variable reporting fraction in different health-care settings make the problem challenging to evaluate. Self-reported symptoms of post-finasteride syndrome include penile
atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulatory system, circulation, loss of hormone, hormonal supp ...
and tissue changes, decreased ejaculate volume and quality, libido loss, erectile dysfunction, loss of penile sensitivity, decreased orgasm sensation, dry skin, metabolic changes, muscle and strength loss,
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 The breast is one of two prominences located on the upper ventral Standard anatomica ...

gynecomastia
, depression, anxiety, panic attacks, insomnia,
anhedonia Anhedonia is a diverse array of deficits in hedonic Hedonism refers to a family of theories, all of which have in common that ''pleasure'' plays a central role in them. ''Psychological'' or ''motivational hedonism'' claims that human behavio ...
, concentration problems, memory impairment and
suicidal ideation Suicidal ideation (or suicidal thoughts) is thinking about, considering, or planning suicide. It is not a diagnosis, but is a symptom of some mental disorder A mental disorder, also called a mental illness or psychiatric disorder, is a beha ...
. A meta-analysis found significant association between finasteride use and post-discontinuation depression, suicide ideation, and sexual dysfunction. Plaintiffs have filed over one thousand court cases against Merck over the effects of finasteride. Most were settled by 2018 when Merck paid a lump sum of US$4.3 million to be distributed. , 25 cases remained outstanding in the United States. In 2019 Reuters reported that faulty redactions in court documents revealed allegations from plaintiffs that Merck had known of persistent side effects in their original clinical trials but chose not to disclose them in warning labels.


Overdose

Finasteride has been studied in humans at single doses of up to 400 mg and at continuous dosages of up to 80 mg/day for three months, without adverse effects observed. There is no specific recommended
antidote An antidote is a substance that can counteract a form of poison In biology, poisons are substances that can cause death, injury or harm to organs, tissues, cells, and DNA usually by chemical reactions or other activity on the molecular ...

antidote
for finasteride overdose.


Interactions

No significant
drug interaction A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug. A cause of a drug interaction involves one drug which alters the pharmacokinetics ...
s have been observed between finasteride and a limited selection of medications.


Pharmacology


Pharmacodynamics

Finasteride is a 5α-reductase inhibitor. It is specifically a
selective Selective may refer to: * Selective school, a school that admits students on the basis of some sort of selection criteria ** Selective school (New South Wales) Selective strength: the human body transitions between being weak and strong. This rang ...
inhibitor of the type II and III
isoform A protein isoform, or "protein variant", is a member of a set of highly similar proteins Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallo ...
s of the
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

enzyme
. By inhibiting these two isozymes of 5α-reductase, finasteride reduces the formation of the potent
androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone A steroid hormone is a steroid , hypothetical a steroid with 32 carbon atoms. Its core ring system (ABCD), composed of 17 c ...
dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous Endogenous substances and processes are those that originate from within a system such as an organism, Tissue (biology), tissue, or Cell ...
(DHT) from its
precursor Precursor or Precursors may refer to: *Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of unre ...
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 system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...
in certain
tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubitata'', a species of geometer mot ...
s in the body such as 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 ...
,
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 cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

skin
, and
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given org ...

hair follicle
s. As such, finasteride is a type of
antiandrogen Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drug File:Aspirine macro shot.jpg, Uncoated aspirin Tablet (pharmacy), tablets, consisting of about 90% acetylsalicylic acid, along with a minor amount o ...
, or more specifically, an androgen synthesis inhibitor. However, some authors do not define finasteride as an "antiandrogen," a term which can refer more specifically to antagonists of the
androgen receptor The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor In the field of molecular biology, nuclear receptors are a class of proteins found within cells that are responsi ...

androgen receptor
. Finasteride results in a decrease of circulating DHT levels by about 65 to 70% with an oral dosage of 5 mg/day and of DHT levels in the prostate gland by up to 80 to 90% with an oral dosage of 1 or 5 mg/day. In parallel, circulating levels of testosterone increase by approximately 10%, while local concentrations of testosterone in the prostate gland increase by about 7-fold and local testosterone levels in hair follicles increase by around 27 to 53%. An oral dosage of finasteride of only 0.2 mg/day has been found to achieve near-maximal suppression of DHT levels (68.6% for 0.2 mg/day relative to 72.2% for 5 mg/day). Finasteride does not completely suppress DHT production because it lacks significant inhibitory effects on the 5α-reductase type I isoenzyme, with more than 100-fold less inhibitory potency for type I as compared to type II ( = 313 nM and 11 nM, respectively). This is in contrast to inhibitors of all three isoenzymes of 5α-reductase like
dutasteride Dutasteride, sold under the brand name Avodart among others, is a medication composed of the molecular ingredients Dutasteride, dissolved in a mixture of mono-di-glycerides of caprylic/capric acid, and butylated hydroxytoluene, primarily used to ...

dutasteride
, which can reduce DHT levels in the entire body by more than 99%. In addition to inhibiting 5α-reductase, finasteride has also been found to competitively inhibit 5β-reductase (AKR1D1). However, its affinity for the enzyme is substantially less than for 5α-reductase (an order of magnitude less than for 5α-reductase ''type I'') and hence is unlikely to be of clinical significance. As of 2012, the tissues in which the different isozymes of 5α-reductase are expressed are not fully clear. This is because different investigators have obtained varying results with different
reagent A reagent is a substance or compound added to a system to cause a chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...
s, methods, and tissues examined. However, the different isozymes of 5α-reductase appear to be widely expressed, with notable tissues including the prostate gland,
seminal vesicle The seminal vesicles (also called vesicular glands, or seminal glands) are a pair of two convoluted tubular glands that lie behind the urinary bladder The urinary bladder, or simply bladder, is a hollow muscular MUSCULAR (DS-200B), located i ...
s,
testes Testicle or testis (plural testes) is the male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male or ...

testes
,
epididymides The epididymis (; plural: epididymides or ) is a tube that connects a testicle Testicle or testis (plural testes) is the male reproductive gland or gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gamete ...

epididymides
, skin, hair follicles,
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

liver
,
kidney The kidneys are two reddish-brown bean-shaped organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized ...

kidney
s, and
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
, among others. By inhibiting 5α-reductase and thus preventing DHT production, finasteride reduces androgen signaling in tissues like the prostate gland and the scalp. In the prostate, this reduces prostate volume, which improves BPH and reduces risk of prostate cancer. Finasteride reduces prostate volume by 20 to 30% in men with benign prostatic hyperplasia. Inhibition of 5α-reductase also reduces weight, and decreases motility and normal morphology of spermatozoa in the epididymis.
NeurosteroidNeurosteroids, also known as neuroactive steroids, are endogenous or exogenous steroid , a steroid with 27 carbon atoms. Its core ring system (ABCD), composed of 17 carbon atoms, is shown with IUPAC The International Union of Pure and Applie ...
s like 3α-androstanediol (derived from DHT) and
allopregnanolone Allopregnanolone, also known as brexanolone, is a naturally produced steroid that acts on the brain. As a medication, it is sold under the brand name Zulresso and used to treat postpartum depression. It is used by injection into a vein Intra ...

allopregnanolone
(derived from
progesterone Progesterone (P4) is an endogenous Endogenous substances and processes are those that originate from within a system such as an organism, Tissue (biology), tissue, or Cell (biology), cell. Endogenous substances and processes contrast with exo ...

progesterone
) activate the in the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
; because finasteride prevents the formation of neurosteroids, it functions as a neurosteroidogenesis inhibitor and may contribute to a reduction of GABAA activity. Reduction of GABAA receptor activation by these neurosteroids has been implicated in
depression Depression may refer to: Mental health * Depression (mood), a state of low mood and aversion to activity * Mood disorders characterized by depression are commonly referred to as simply ''depression'', including: ** Dysthymia ** Major depressive ...
,
anxiety Anxiety is an emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or suffering, disp ...

anxiety
, and
sexual dysfunction Sexual dysfunction is difficulty experienced by an individual or partners during any stage of normal Human sexual activity, sexual activity, including physical pleasure, Sexual desire, desire, preference, sexual arousal, arousal, or orgasm. The Wor ...
.


Pharmacokinetics

The mean
oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or oral ...

oral
bioavailability In pharmacology, bioavailability (''BA or F'') is a subcategory of absorption and is the fraction (%) of an administered medication, drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its ...
of finasteride is approximately 65%. The
absorption Absorption may refer to: Chemistry and biology *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which substances enter the body through the skin *Absorption (pharmacolo ...
of finasteride is not affected by food. At
steady-state In systems theory Systems theory is the interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic disciplines into one activity (e.g., a research project). It draws knowledge from s ...
with 1 mg/day finasteride, mean peak concentrations of finasteride were 9.2 ng/mL (25 nmol/L). Conversely, following a single 5 mg dose of finasteride, mean peak levels of finasteride were 37 ng/mL (99 nmol/L), and plasma concentrations increased by 47 to 54% following 2.5 weeks of continued daily administration. The
volume of distribution In pharmacology, the volume of distribution (VD, also known as apparent volume of distribution, literally, ''volume of dilution'') is the theoretical volume that would be necessary to contain the total amount of an administered drug at the same co ...
of finasteride is 76 L. Its
plasma protein binding Plasma protein binding refers to the degree to which medications attach to proteins within the blood. A drug's efficiency may be affected by the degree to which it binds. The less bound a drug is, the more efficiently it can traverse cell membrane ...
is 90%. The drug has been found to cross the
blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solution, solutes in the circulating blood from ''non-selectively'' crossing into the extracellular ...
, whereas levels in
semen Semen, also known as seminal fluid, is an organic fluid created to contain spermatozoon, spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphrodite, hermaphroditic animals and can fertilization, f ...

semen
were found to be undetectable. Finasteride is extensively
metabolized Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities A bubble of exhaled gas in water In common usage and classical mechanics, a phys ...

metabolized
in the
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

liver
, first by
hydroxylation In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in th ...
via
CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme Enzymes () are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , ...

CYP3A4
and then by
aldehyde dehydrogenase Aldehyde dehydrogenases () are a group of enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), s ...
. It has two major
metabolite In biochemistry Biochemistry or biological chemistry, is the study of es within and relating to living s. A sub-discipline of both and , biochemistry may be divided into three fields: , and . Over the last decades of the 20th century, bio ...
s, which are the ''tert''-
butyl In organic chemistry Organic chemistry is a branch of chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, prope ...

butyl
side chain In organic chemistry Organic chemistry is a branch of that studies the structure, properties and reactions of s, which contain in .Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . ...
monohydroxylated and monocarboxylic acid metabolites. These metabolites show approximately 20% of the inhibitory activity of finasteride on 5α-reductase. Hence, the metabolites of finasteride are not particularly active. The drug has a terminal half-life of 5 to 6 hours in adult men (18–60 years of age) and a terminal half-life of 8 hours or more in elderly men (more than 70 years of age). It is elimination (pharmacology), eliminated as its metabolites 57% in the feces and 40% in the urine.


Chemistry

Finasteride, also known as 17β-(''N''-tert-butylcarbamoyl)-4-aza-5α-androst-1-en-3-one, is a synthetic compound, synthetic androstane steroid and 4-azasteroid. It is an structural analogue, analogue of androgen steroid hormones like testosterone and DHT. As an unconjugated steroid, finasteride is a highly lipophilic compound.


History

In 1942, James Hamilton observed that prepubertal castration prevents the later development of male pattern baldness in mature men. In 1974, Julianne Imperato-McGinley of Cornell Medical College in New York attended a conference on birth defects. She reported on a group of intersex children in the Caribbean who appeared sexually Ambiguity, ambiguous at birth, and were initially raised as girls, but then grew external male genitalia and other masculine characteristic after onset of puberty. These children, despite being raised as girls until puberty, were generally heterosexual, and were termed "Guevedoces" by their local community, which means "penis at twelve" in Spanish. Her research group found these children shared a genetic mutation, causing 5-alpha-reductase deficiency, deficiency of the 5α-reductase enzyme and male hormone
dihydrotestosterone Dihydrotestosterone (DHT, 5α-dihydrotestosterone, 5α-DHT, androstanolone or stanolone) is an endogenous Endogenous substances and processes are those that originate from within a system such as an organism, Tissue (biology), tissue, or Cell ...
(DHT), which was found to have been the etiology behind abnormalities in male sexual development. Upon maturation, these individuals were observed to have smaller prostates which were underdeveloped, and were also observed to lack incidence of male pattern baldness. In 1975, copies of Imperato-McGinley's presentation were seen by P. Roy Vagelos, who was then serving as Merck & Co., Merck's basic-research chief. He was intrigued by the notion that decreased levels of DHT led to the development of smaller prostates. Dr. Vagelos then sought to create a drug which could mimic the condition found in these children to treat older men who were suffering from benign prostatic hyperplasia. Finasteride was developed by Merck under the code name MK-906. A team led by chemist Gary Rasmusson and biologist Jerry Brooks developed potential 5α-reductase inhibitors based on transition state inhibitors, using an iterative process of molecular design, testing, and redesign. In 1992, finasteride (5 mg) was approved by the Food and Drug Administration (United States), U.S. Food and Drug Administration (FDA) for treatment of BPH, which Merck marketed under the brand name Proscar. Rasmusson and Brooks were awarded IPO's “Inventor of the Year” award in 1993 for their work on finasteride. In 1997, Merck was successful in obtaining FDA approval for a second indication of finasteride (1 mg) for treatment of male pattern hair loss, which was marketed under the brand name Propecia. It was the first 5α-reductase inhibitor to be introduced and was followed by
dutasteride Dutasteride, sold under the brand name Avodart among others, is a medication composed of the molecular ingredients Dutasteride, dissolved in a mixture of mono-di-glycerides of caprylic/capric acid, and butylated hydroxytoluene, primarily used to ...

dutasteride
in 2001. The first study of finasteride in the treatment of hirsutism in women was published in 1994.


Society and culture


Generic names

''Finasteride'' is the generic term, generic name of the drug and its , , , and , while ''finastéride'' is its . It is also known by its former developmental code names ''MK-906'', ''YM-152'', and ''L-652,931''.


Brand names

Finasteride is marketed primarily under the brand names Propecia, for pattern hair loss, and Proscar, for BPH, both of which are products of Merck & Co. There is 1 mg of finasteride in Propecia and 5 mg in Proscar. Merck's patent on finasteride for the treatment of BPH expired in June 2006. Merck was awarded a separate patent for the use of finasteride to treat pattern hair loss and it expired in November 2013. Finasteride is also marketed under a variety of other brand names throughout the world.


Athletics

From 2005 to 2009, the World Anti-Doping Agency banned finasteride because it was discovered that the drug could be used to mask anabolic steroids, steroid abuse. It was removed from the list effective 1 January 2009, after improvements in testing methods made the ban unnecessary. Athletes who used finasteride and were banned from international competition include Skeleton (sport), skeleton racer Zach Lund, Bobsleigh, bobsledder Sebastien Gattuso, Football (soccer), footballer Romário, and Goaltender, ice hockey goaltender José Théodore.


Miscellaneous

The U.S.
Food and Drug Administration The United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, st ...
advises that donation of blood or plasma be deferred for at least one month after taking the last dose of finasteride. The UK also has a one-month deferral period. Harold Bornstein, the former personal physician of President of the United States, United States President Donald Trump, stated in 2017 that Trump was taking finasteride to promote hair growth.


Research

Preliminary research suggests that topical medication, topical finasteride may be effective in the treatment of pattern hair loss. Topical finasteride, like the oral preparation, reduces serum DHT. DHT may be involved in the cause of acne, and 5α-reductase inhibitors might be effective in the treatment of the condition. A small retrospective study reported that finasteride was effective in the treatment of acne in women with normal
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 system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...
levels. A randomized controlled trial found that finasteride was less effective than flutamide or an ethinylestradiol/cyproterone acetate birth control pill in the treatment of acne in women with hyperandrogenism, high androgen levels. Androgens and estrogens may be involved in the cause of hidradenitis suppurativa (acne inversa). Two case series have reported that finasteride is effective in the treatment of hidradenitis suppurativa in girls and women. Finasteride and other antiandrogens might be useful in the treatment of obsessive–compulsive disorder, but more research is needed.


References


External links

* {{Portal bar , Medicine Wikipedia medicine articles ready to translate 5α-Reductase inhibitors Androstanes Merck & Co. brands Carboxamides Hair loss medications Hair removal Delta-lactams Teratogens Tert-butyl compounds