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A novel finasteride 0.25% topical solution for androgenetic alopecia: pharmacokinetics and effects on plasma androgen levels in healthy male volunteers

Caserini M, Radicioni M, Leuratti C, et al. (2014)

Int J Clin Pharmacol Ther · PMID 25074865

Abstract

OBJECTIVE: Finasteride, a selective inhibitor of type 2 5-&#x3b1; reductase isoenzyme, inhibits the conversion of testosterone to dihydrotestosterone (DHT) and is indicated in the treatment of male androgenetic alopecia. The study objective was to evaluate a newly developed finasteride 0.25% topical solution in comparison to the marketed finasteride 1 mg tablet, with respect to finasteride pharmacokinetics and suppressive effects on plasma DHT. METHODS: 24 healthy men with androgenetic alopecia were randomized in a single center, open-label, parallel-group, exploratory study, and received either multiple scalp applications of the topical solution b.i.d. or oral doses of the reference tablet o.d. for 7 days. Plasma finasteride, testosterone and DHT concentrations were determined. RESULTS: After multiple doses, mean (&#xb1; SD) finasteride C(max) and AUC(0-t) corresponded to 0.46 &#xb1; 0.28 ng/mL and 6.64 &#xb1; 7.50 ng/mL x h for the topical solution and to 6.86 &#xb1; 1.78 ng/mL and 57.93 &#xb1; 29.38 ng/mL x h for the tablet. Plasma DHT was reduced by ~ 68 - 75% with the topical solution and by ~ 62 - 72% with the tablet. No relevant changes occurred for plasma testosterone with either treatment. No clinically significant adverse events occurred. CONCLUSIONS: A strong and similar inhibition of plasma DHT was found after 1 week of treatment with the topical and tablet finasteride ormulations, albeit finasteride plasma exposure was significantly lower with the topical than with the oral product (p < 0.0001).