The Pharmacokinetics of Topical Finasteride 0.25% Spray in Chinese Adult Male Volunteers with Androgenic Alopecia: A Phase I Study

IntroductionThis study aimed to evaluate the pharmacokinetics (PK), safety, and local tolerability of local finasteride spray (0.25% solution in HPCH, once daily, volume 200 mu L) after single and multiple doses in Chinese male volunteers with androgenetic alopecia.MethodsTwelve male patients with androgenetic alopecia received once-daily scalp application of the solution for 7 days. Blood samples were collected at specified time points (on day 1, days 3-6, and day 7 of the trial) and plasma finasteride concentrations were determined by HPLC-MS.ResultsAfter single-dose administration, the Cmax of finasteride was 15.2 +/- 5.54 pg/mL, Tmax was 11.00 (3.00, 20.00) h, AUC0-24h was 263 +/- 76.6 h<middle dot>pg/mL, t1/2 was 35.3 +/- 47.7 h, and CL/F was 974 +/- 518 L/h. After 7 days of multiple doses, Cmax,ss was 29.7 +/- 12.9 pg/mL, Tmax,ss was 8.00 (3.00, 12.00) h, AUCtau,ss was 530 +/- 251 h<middle dot>pg/mL, AUC0-t,ss was 790 +/- 464 h<middle dot>pg/mL, t1/2,ss was 22.6 +/- 10.7 h, and CL/Tss was 1080 +/- 658 L/h. No clinically significant adverse events occurred during the study.ConclusionCompared to single-dose administration, multiple-dose administration of finasteride resulted in a stable half-life, minimal changes in clearance rate, and approximately twofold accumulation in exposure over 7 days. Multiple-dose administration of finasteride spray was well tolerated in Chinese male volunteers with androgenetic alopecia.