Department of Clinical Pharmacology and Biostatistics, Merck Research Laboratories,
Rahway, NJ 07065-0914.
Source
Clin Pharmacol Ther, 55: 1, 1994 Jan, 50-4
Abstract
The hormonal effects after a 10-day administration of a 4-azasteroid inhibitor of 5
alpha-reductase, MK-0963 (previously L-654,066), were evaluated in 35 healthy male
volunteers in an increasing-dose, five-panel design. Marked suppression of serum
dihydrotestosterone was observed after the once-daily administration at each active dose
level (placebo, 0.1, 0.5, 1.0, 10, and 25 mg). Maximum dihydrotestosterone suppression
occurred at doses greater than or equal to 10 mg. The mean percentage (+/- SE) decreases
in dihydrotestosterone at 24 hours after the last dose in the groups treated with the 10
and 25 mg doses were 78% +/- 4.9% and 80% +/- 2.9%, respectively. The 25 mg dose
maintained a dihydrotestosterone suppression of at least 70% for more than 6 days after
the last dose. No consistent changes in serum testosterone were noted. This study shows
that administration of multiple doses of MK-0963 results in a substantial suppression of
serum dihydrotestosterone with no consistent influence on serum testosterone
concentrations.