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 ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes ...

and

anabolic steroid Anabolic steroids, also known as anabolic-androgenic steroids (AAS), are a class of drugs that are structurally related to testosterone, the main male sex hormone, and produce effects by binding to the androgen receptor (AR). Anabolism, Anaboli ...

(AAS) medication which is used in

veterinary medicine Veterinary medicine is the branch of medicine that deals with the prevention, management, medical diagnosis, diagnosis, and treatment of disease, disorder, and injury in non-human animals. The scope of veterinary medicine is wide, covering all a ...

, 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 mi ...

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 of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects. A drug or procedure usually use ...

s of boldenone undecylenate include

symptom Signs and symptoms are diagnostic indications of an illness, injury, or condition. Signs are objective and externally observable; symptoms are a person's reported subjective experiences. A sign for example may be a higher or lower temperature ...

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 a medical term commonly used in three medical a ...

acne Acne ( ), also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...

, increased hair growth, voice changes, and increased sexual desire. The drug is a synthetic androgen and anabolic steroid and hence is an

agonist An agonist is a chemical that activates a Receptor (biochemistry), receptor to produce a biological response. Receptors are Cell (biology), cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an R ...

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 th ...

(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 male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...

and dihydrotestosterone (DHT). It has strong

anabolic Anabolism () is the set of metabolic pathways that construct macromolecules like DNA or RNA from smaller units. These reactions require energy, known also as an endergonic process. Anabolism is the building-up aspect of metabolism, whereas catab ...

effects and moderate

ic effects, weak

estrogen Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...

ic effects, and no risk of liver damage. Boldenone undecylenate is an androgen ester and a long-lasting

prodrug A prodrug is a pharmacologically inactive 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 ...

of boldenone 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 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 country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Uses

Veterinary

Boldenone undecylenate is used in

, mainly in

Clinical

Boldenone undecylenate was formerly used in

clinical medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

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 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 respo ...

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

Side effects

Pharmacology

Pharmacodynamics

Boldenone undecylenate is a

of boldenone, 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 progestogenic 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 (DILI) is a cause of acute and chronic liver disease caused specifically by medications and the most common reason for a drug to be withdr ...

Pharmacokinetics

Boldenone undecylenate is a

of boldenone. When administered via

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

, 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 (elimination half-life, pharmacological half-life) is the time taken for concentration of a drug, biological substance (such as a medication) to decrease from its maximum concentration (chemistry), concentration (Cmax (pharm ...

of 14 days when administered by

. Boldenone is a substrate for 5α-reductase and may be converted by this

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

into 1-testosterone (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 betwee ...

s, and

prostate gland The prostate is an male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemica ...

. However, its

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 Pa ...

for this enzyme is said to be extremely low.

Chemistry

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

steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...

and a

derivative In mathematics, the derivative is a fundamental tool that quantifies the sensitivity to change of a function's output with respect to its input. The derivative of a function of a single variable at a chosen input value, when it exists, is t ...

. It is the C17β undecylenate (undecenoate)

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

of boldenone (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 A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical ...

androgen found in the scent gland of ''Ilybius fenestratus'' (a species of aquatic beetle). Boldenone is the non- 17α-alkylated variant of

metandienone Metandienone, also known as methandienone or methandrostenolone and sold under the brand name Dianabol (D-Bol) among others, is an androgen and anabolic steroid (AAS) medication which is mostly no longer prescribed. It is also used non-medically ...

(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 sufficiency of disclosure, enabling discl ...

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 work (human activity), works in a specified professional activity. The term also describes the standards of education and training that prepare members of the profession with the partic ...

athlete An athlete is most commonly a person who competes in one or more sports involving physical strength, speed, power, or endurance. Sometimes, the word "athlete" is used to refer specifically to sport of athletics competitors, i.e. including track ...

References

{{Estrogen receptor modulators Anabolic–androgenic steroids Androstanes Androgen esters Conjugated dienes Equine medications Enones Synthetic estrogens Undecylenate esters