Finasteride
no longer prohibited as of January 1, 2009
Definition
Finasteride, a 5-alpha-reductase inhibitor, was first banned by WADA as a masking agent on January 1, 2005 (see below). Since January 1, 2009, finasteride is no longer banned as a doping substance!
Finasteride (Fig. 1) is an active ingredient that leads to selective inhibition of 5-alpha-reductase. 5-alpha-reductase is an enzyme responsible for the conversion of testosterone to dihydrotestosterone in the human body (see Fig. 2).
History
Since 1994, finasteride has been used at a dosage of 5 mg per day to treat benign prostatic hyperplasia. In this condition, elevated levels of the androgen 5-alpha-dihydrotestosterone in the prostate cause excessive growth of prostate tissue.
Since January 1999, finasteride has also been approved in Germany as a treatment for genetically caused hair loss (androgenetic alopecia) in young men, whereby the androgen responsible for the development of androgenetic alopecia is also 5-alpha-dihydrotestosterone. The recommended dosage for the treatment of androgenetic alopecia is 1 mg per day.
Significance as a Doping Agent
Due to finasteride’s effect on steroid metabolism, the detection of steroids banned in sports—whose primary metabolites are 5-alpha-steroids—is made more difficult. These steroids include the 19-norsteroids nandrolone, norandrostendione, and norandrostendiol, as well as dihydrotestosterone. Finasteride leads to a reduction in the excretion of 5-alpha metabolites. Consequently, taking finasteride causes a significant change in the profile of endogenous steroids, thereby rendering the steroid profile meaningless in the context of long-term studies.
For the reasons mentioned above, finasteride was added by WADA in January 2005 to the list of prohibited substances in the group "S5. Diuretics and other masking agents." Finasteride was subsequently banned in both training and competition. This ban was lifted on January 1, 2009.
References
Geyer, H., Gorius, I., Dreyer, N., Mareck, U., Thevis, M., Schänzer, W.: Investigation into the effects and detection of finasteride. In: W. Schänzer, H. Geyer, A. Gotzmann, U. Mareck (eds.) Recent advances in doping analysis (13). Sport und Buch Strauß, Cologne (2005) 479–482
Institute of Biochemistry at the DSHS Cologne, last updated August 2, 2010