Quinbolone
Encyclopedia
Quinbolone is an anabolic steroid
with weak androgen
ic effects. It was developed by Parke-Davis
in an attempt to create a viable orally-administered anabolic steroid with little or no liver toxicity
.
The drug is atypical in that steroid molecules
are usually only given officially distinct names when there is a permanent structural difference between the parent molecule and itself. Quinbolone, however, differs from its parent molecule (boldenone
) solely by the addition of an easily removed cyclopentenyl ether
group.
Most orally administered anabolic steroids function by having an alkylated 17α-carbon
atom, which prevents first-pass metabolism by the liver. This approach does, however, give the drug a high hepatotoxicity
. Quinbolone is not 17α-alkylated; instead it has increased oral bioavailability
due to its cyclopentenyl ether group. This allows the drug to be fully dissolved in an oil base, which is then absorbed into the lymphatic system
via the large intestine
, from which it travels into the blood. Once there the ester group detaches and the relatively inactive quinbolone becomes boldenone, which then reacts with the androgen receptor
of any muscles it comes into contact with.
Quinbolone itself has very few androgenic effects, and most of what it does have are a result of its conversion to boldenone and its metabolite
s. This, combined with its unusual route of absorption, provides the drug with highly variable results, meaning that large quantities of the drug (100-200 mg per day) must be taken in order to maintain high enough concentrations in the blood for noticeable and consistent effects. The cost and inconvenience of this meant that quinbolone never proved commercially successful, and its clinical applications were fulfilled by alternative, more effective, steroids. Its illicit usage in bodybuilding
and athletics
likewise proved limited, though drug tests are still used to detect its metabolites as it remains a banned substance for most competitive sports.
Anabolic steroid
Anabolic steroids, technically known as anabolic-androgen steroids or colloquially simply as "steroids", are drugs that mimic the effects of testosterone and dihydrotestosterone in the body. They increase protein synthesis within cells, which results in the buildup of cellular tissue ,...
with weak androgen
Androgen
Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors...
ic effects. It was developed by Parke-Davis
Parke-Davis
Parke-Davis is a subsidiary of the pharmaceutical company Pfizer. Although no longer an independent corporation, it was once America's oldest and largest drug maker, and played an important role in medical history.- History :...
in an attempt to create a viable orally-administered anabolic steroid with little or no liver toxicity
Hepatotoxicity
Hepatotoxicity implies chemical-driven liver damage.The liver plays a central role in transforming and clearing chemicals and is susceptible to the toxicity from these agents. Certain medicinal agents, when taken in overdoses and sometimes even when introduced within therapeutic ranges, may injure...
.
The drug is atypical in that steroid molecules
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
are usually only given officially distinct names when there is a permanent structural difference between the parent molecule and itself. Quinbolone, however, differs from its parent molecule (boldenone
Boldenone
Boldenone , also known under the trade names Equipoise, Ganabol, Equigan and Ultragan, is an anabolic steroid developed for veterinary use, mostly for treatment of horses...
) solely by the addition of an easily removed cyclopentenyl ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
group.
Most orally administered anabolic steroids function by having an alkylated 17α-carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atom, which prevents first-pass metabolism by the liver. This approach does, however, give the drug a high hepatotoxicity
Hepatotoxicity
Hepatotoxicity implies chemical-driven liver damage.The liver plays a central role in transforming and clearing chemicals and is susceptible to the toxicity from these agents. Certain medicinal agents, when taken in overdoses and sometimes even when introduced within therapeutic ranges, may injure...
. Quinbolone is not 17α-alkylated; instead it has increased oral bioavailability
Bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered...
due to its cyclopentenyl ether group. This allows the drug to be fully dissolved in an oil base, which is then absorbed into the lymphatic system
Lymphatic system
The lymphoid system is the part of the immune system comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally toward the heart. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated...
via the large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
, from which it travels into the blood. Once there the ester group detaches and the relatively inactive quinbolone becomes boldenone, which then reacts with the androgen receptor
Androgen receptor
The androgen receptor , also known as NR3C4 , is a type of nuclear receptor that is activated by binding of either of the androgenic hormones testosterone or dihydrotestosterone in the cytoplasm and then translocating into the nucleus...
of any muscles it comes into contact with.
Quinbolone itself has very few androgenic effects, and most of what it does have are a result of its conversion to boldenone and its metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
s. This, combined with its unusual route of absorption, provides the drug with highly variable results, meaning that large quantities of the drug (100-200 mg per day) must be taken in order to maintain high enough concentrations in the blood for noticeable and consistent effects. The cost and inconvenience of this meant that quinbolone never proved commercially successful, and its clinical applications were fulfilled by alternative, more effective, steroids. Its illicit usage in bodybuilding
Bodybuilding
Bodybuilding is a form of body modification involving intensive muscle hypertrophy. An individual who engages in this activity is referred to as a bodybuilder. In competitive and professional bodybuilding, bodybuilders display their physiques to a panel of judges, who assign points based on their...
and athletics
Athletics (track and field)
Athletics is an exclusive collection of sporting events that involve competitive running, jumping, throwing, and walking. The most common types of athletics competitions are track and field, road running, cross country running, and race walking...
likewise proved limited, though drug tests are still used to detect its metabolites as it remains a banned substance for most competitive sports.