Boldenone undecylenate, or boldenone undecenoate, sold under the brand names Equipoise and Parenabol among others, is an

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 ...

and

anabolic steroid Anabolic steroids, also known more properly as anabolic–androgenic steroids (AAS), are steroidal androgens that include natural androgens like testosterone as well as synthetic androgens that are structurally related and have similar effects ...

(AAS) medication which is used in

veterinary medicine Veterinary medicine is the branch of medicine that deals with the prevention, management, diagnosis, and treatment of disease, disorder, and injury in animals. Along with this, it deals with animal rearing, husbandry, breeding, research on nutri ...

, mainly in

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

s. It was formerly used in humans as well. It is given by injection into muscle.

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 ...

s of boldenone undecylenate include

symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showi ...

s of

masculinization 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 ...

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 ...

, increased hair growth,

voice changes ' A voice change or voice mutation, sometimes referred to as a voice break or voice crack, commonly refers to the deepening of the voice of men as they reach puberty. Before puberty, both sexes have roughly similar vocal pitch, but during puberty ...

, and increased sexual desire. The drug is a

synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic ...

androgen and anabolic steroid and hence is an

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ag ...

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 that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone in ...

(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 androgens like

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 includi ...

(DHT). It has strong

anabolic Anabolism () is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catabolism is the breakin ...

effects and moderate

ic effects, weak

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, and no risk 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 ...

. Boldenone undecylenate is an

androgen ester An androgen or anabolic steroid ester is an ester of an androgen/anabolic steroid (AAS) such as the natural testosterone or dihydrotestosterone (DHT) or the synthetic nandrolone (19-nortestosterone). Esterification renders AAS into metabolism-re ...

and a long-lasting

prodrug A prodrug is a medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the dru ...

boldenone Boldenone (developmental code name RU-18761), is a naturally occurring anabolic–androgenic steroid (AAS) and the 1(2)-dehydrogenated analogue of testosterone. Boldenone itself has never been marketed; as a pharmaceutical drug, it is used as ...

in the body. Boldenone undecylenate was introduced for medical use in the 1960s. In addition to its medical use, boldenone undecylenate is used to improve physique and performance. The drug is 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 the United States and its use is generally illicit. It remains marketed for veterinary use in

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

and 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, states, a Washington, D.C., ...

Uses

Veterinary

Boldenone undecylenate is used in

, mainly in

Clinical

Boldenone undecylenate was formerly used in

clinical medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practice ...

in humans, but was discontinued. The drug is currently not approved by

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

. It is also classified as DEA Schedule III controlled substance.

Side effects

Pharmacology

Pharmacodynamics

Boldenone undecylenate is a

, and hence is an

of the

. Boldenone has strong

effects and moderate

ic effects. It also has low

ic activity and has little or no

progestogen Progestogens, also sometimes written progestagens or gestagens, are a class of natural or synthetic steroid hormones that bind to and activate the progesterone receptors (PR). Progesterone is the major and most important progestogen in the bod ...

ic activity. In relation to the fact that it is not 17α-alkylated, boldenone and boldenone undecylenate have little or no risk of

hepatotoxicity Hepatotoxicity (from ''hepatic toxicity'') implies chemical-driven liver damage. Drug-induced liver injury is a cause of acute and chronic liver disease caused specifically by medications and the most common reason for a drug to be withdrawn fr ...

Pharmacokinetics

Boldenone undecylenate is a

. When administered via

intramuscular injection Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles hav ...

, a depot is formed from which boldenone undecylenate is slowly released into the body and then transformed into boldenone. The drug possess a

biological 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 14 days when administered by

. Boldenone is a substrate for

5α-reductase 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 o ...

and may be converted by this

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 ...

into

1-testosterone 1-Testosterone (abbreviated and nicknamed as 1-Testo, 1-T), also known as δ1-dihydrotestosterone (δ1-DHT), as well as dihydroboldenone, is a synthetic anabolic–androgenic steroid (AAS) and a 5α-reduced derivative of boldenone (Δ1-testost ...

(δ¹-dihydrotestosterone, δ¹-DHT, dihydroboldenone) in tissues that express it such as the

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 ...

hair follicle The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between ...

s, and

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 physi ...

. However, its affinity for this enzyme is said to be extremely low.

Chemistry

Boldenone undecylenate, or boldenone 17β-undec-10-enoate, is a

androstane

steroid 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 ...

and a

derivative In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. ...

. It is the C17β undecylenate (undecenoate)

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

(δ¹-testosterone, 1-dehydrotestosterone, or androsta-1,4-dien-17β-ol-3-one), which itself is the C1(2) dehydrogenated analogue of testosterone and a naturally occurring androgen found in the

scent gland Scent gland are exocrine glands found in most mammals. They produce semi-viscous secretions which contain pheromones and other semiochemical compounds. These odor-messengers indicate information such as status, territorial marking, mood, and s ...

of ''Ilybius fenestratus'' (a species of aquatic beetle). Boldenone is the non- 17α-alkylated variant of metandienone (17α-methyl-δ¹-testosterone). An AAS related to boldenone undecylenate is quinbolone (δ¹-testosterone 17β-cyclopentenyl enol ether).

History

Boldenone was reportedly

patent 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 ...

ed by Ciba in 1949, and

s of the compound were developed by the company in the 1950s and 1960s. One such ester, boldenone undecylenate, was introduced for clinical use as an injectable AAS under the brand name ''Parenabol'' in the 1960s. However, it was discontinued for use in humans in the late 1970s. Squibb introduced boldenone undecylenate for veterinary use under the brand name Equipoise. The medication has been used much more widely in veterinary medicine, in which it has been used mainly in horses, and remains in use today.

Society and culture

Generic names

''Boldenone undecylenate'' is the generic name of the drug and its , while ''boldenone undecenoate'' is its .

Brand names

Boldenone undecylenate is or has been marketed under a number of brand names including Boldane, Equipoise, Parenabol, and Vebonol among others.

Availability

Boldenone undecylenate remains marketed for veterinary use in

and the

Doping in sports

There are many known cases of doping in sports with boldenone undecylenate by

professional A professional is a member of a profession or any person who works in a specified professional activity. The term also describes the standards of education and training that prepare members of the profession with the particular knowledge and sk ...

athlete An athlete (also sportsman or sportswoman) is a person who competes in one or more sports that involve physical strength, speed, or endurance. Athletes may be professionals or amateurs. Most professional athletes have particularly well-de ...

References

External links

Equipoise (boldenone undecylenate) - William Llewellyn's Anabolic.org
{{Estrogen receptor modulators Androgens and anabolic steroids Androstanes Androgen esters Conjugated dienes Equine medications Enones Prodrugs Synthetic estrogens Undecylenate esters World Anti-Doping Agency prohibited substances