Pharmacology of Topical Finasteride Formulations in Rats
January 2018
TLDR Topical finasteride accumulates in the skin with minimal absorption into the bloodstream.
This study investigated the pharmacokinetics of a 0.5% finasteride topical formulation in male Sprague-Dawley rats. It aimed to measure finasteride levels in plasma and skin after single and repeated applications. Results showed that finasteride was minimally absorbed into the bloodstream, with detectable plasma levels only after a single application of 300 µl. Repeated applications (1 or 2 times daily for 7 days) did not significantly affect plasma levels. The skin-to-blood ratio was approximately 2.6, indicating that finasteride remained primarily in the dermis. The study suggests that topical finasteride has limited systemic absorption and may not cause significant systemic effects.