Metabolism of testosterone and its ester derivatives in organotypic coculture of human dermal fibroblasts with differentiated epidermis

The metabolism of testosterone (TS) and its 17-O-acyl derivatives (acyl = acetyl, benzoyl and hemi-succinoyl) was studied using radioactive compounds in organotypic coculture of human dermal fibroblasts (living skin equivalent, LSE). When TS was applied to the epidermal-side of LSE in a small volume of acetone solution, both 5α-reduced and 17-dehydrogenated metabolites were observed in the dermal-side culture solution, though the formation of the 5α-reduced metabolites, dihydrotestosterone (DHT) and dihydroandrosterone (DHA), depended greatly on the culture conditions. The metabolic activity of LSE for testosterone was higher than that of excised hairless-rat skin. The metabolism of ester prodrugs of TS in LSE was dependent on their physicochemical properties and susceptibility to enzymatic hydrolysis. Application of acetyl-TS and benzoyl-TS resulted in a high formation of the 17-dehydrogenated metabolite, androstenedione (ADO), though a very small amount of the prodrug was observed in the dermal side. Succinoyl-TS, a hydrophilic ester with very low susceptibility to hydrolysis, was quite resistant to both 5α-reduction and 17-dehydrogenation, and more than 90% of the radioactivity appearing on the dermal side was from the prodrug itself and from TS. The hydrophilic and enzymatically stable TS derivative may be a good candidate compound with which to administer TS transdermally.