|This article possibly contains original research. (January 2010)|
Trenbolone is a steroid used by veterinarians on livestock to increase muscle growth and appetite. To increase its effective half-life, trenbolone is not used in an unrefined form, but is rather administered as ester derivatives such as trenbolone acetate, trenbolone enanthate or trenbolone cyclohexylmethylcarbonate (Parabolan). Plasma lipases then cleave the ester group in the bloodstream leaving free trenbolone.
Bodybuilders and athletes have been known to use the drug illicitly because they experience an increase body mass more effectively than by weight training alone and because of its reputation as a fat-burning as well as bulking agent. In the United States possession or use of trenbolone for humans is a violation of federal law. The DEA classifies trenbolone as a schedule III drug. Trenbolone is classified as a Schedule 4 drug in Canada and a class C drug with no penalty for personal use or possession in the United Kingdom. Use or possession of steroids without a prescription is a crime in Australia. It is nonetheless available over the counter in many countries and fully legal for use there.
Use and effects
Trenbolone acetate is often referred to as "Fina" by users, because injectable trenbolone acetate was originally adapted for use by bodybuilders from dissolution of Finaplix H pellets, an ear implant used by cattle ranchers to maintain the weight of cattle during shipping to slaughter. Studies have shown that trenbolone improves muscle mass in cattle and also feed efficiency and mineral absorption.
Trenbolone compounds have a binding affinity for the androgen receptor five times as high as that of testosterone. Once metabolized, the drugs have the effect of increasing nitrogen uptake by muscles, leading to an increase in the rate of protein synthesis. It may also have the secondary effects of stimulating appetite and decreasing the rate of catabolism, as all anabolic steroids are believed to; however, catabolism likely increases significantly once the steroid is no longer taken. Trenbolone has proven popular with anabolic steroid users, as some believe it is not metabolized by aromatase or 5α-reductase into estrogenic compounds such as estradiol, or into dihydrotestosterone (DHT); however, studies on this are mixed, with some studies showing a potential increase in both. At least one study in rats has shown that trenbolone causes gene expression with the androgen receptor at least as potent as DHT. This evidence tends to indicate Trenbolone can cause an increase in male secondary sex characteristics without the need to convert to DHT.
Since steroids generally cause virilization effects in women in even small doses, this drug should not be taken by women. Kidney toxicity has been suggested, but has not yet been proven, and scientific evidence supporting the idea is absent from the bodybuilding community that perpetuates this idea. The origin of this myth most likely has to do with the rust-colored oxidized metabolites of trenbolone which are excreted in urine and often mistaken for blood. Trenbolone and 17epi-trenbolone are both excreted in urine as conjugates that can be hydrolyzed with beta-glucuronidase. This implies that trenbolone leaves the body as beta-glucuronides or sulfates.