MK-386, an Inhibitor of 5α-Reductase Type 1, Reduces Dihydrotestosterone Concentrations in Serum and Sebum Without Affecting Dihydrotestosterone Concentrations in Semen

The study investigated the effects of MK-386, a 5α-reductase type 1 inhibitor, on dihydrotestosterone (DHT) levels in 100 men over 14 days. MK-386 significantly reduced serum and sebum DHT concentrations in a dose-dependent manner, with the highest dose (50 mg) reducing serum DHT by 22.2% and sebum DHT by 49.1%. In contrast, finasteride, a 5α-reductase type 2 inhibitor, reduced serum DHT by 65.8% and sebum DHT by 14.9%, but significantly decreased semen DHT by 88%. MK-386 did not significantly affect semen DHT levels. The study suggested that MK-386 could be useful for treating conditions like acne due to its ability to suppress sebum DHT without affecting semen DHT. MK-386 was well tolerated, though some subjects experienced reversible liver enzyme elevations at higher doses.