Rate and extent of percutaneous absorption of sertaconazole nitrate after topical administration

The purpose of this open study was to evaluate the rate and extent of the penetration of sertaconazole nitrate (CAS 99592-32-2, Zalaïn) penetration into the stratum corneum/lucidum of the human skin. Selected areas of 9 cm2 each of the back skin of 12 healthy volunteers were exposed over 8 different time intervals (between 0 and 48 h) to 100 mg of a 2% cream preparation of the compound or to placebo. Using a HPLC-assay the relative amounts of the applied dose of sertaconazole nitrate were determined in the residual cream of the skin surface as well as in 3 layers of the epidermis obtained by the stripping technique. Sertaconazole nitrate was shown to penetrate into the stratum corneum shortly after application, disappearing from the application areas with a mean apparent half-life of approximately 60 h. Immediately after topical application the residual amount of the applied mean dose of 2103 +/- 146.3 microg on the skin's surface was 88.9 +/- 2.3%, decreasing steadily to 52.4 +/- 8.5% after 48 h. A relevant amount of the applied dose (5.3 +/- 3.0%) was recovered from the stratum corneum already 30 min after application, and 3 h after administration a plateau was reached (6.9 +/- 3.2) which could be maintained until 48 h. A gradient from the site of application to the epidermis was apparent since the amounts recovered in The estimated average level of sertaconazole nitrate for a volume of 1 mL of stratum corneum after application of 100 mg cream was 1409 microg immediately after application and reached a plateau at 3 h with 9029 microg. Although not directly measured, the results also gave information about the mean amount of sertaconazole nitrate that penetrated through the stratum corneum and deeper layers allowing an estimate of the total mean amount of compound penetrating into the skin. The relative portion of this amount steadily increased from 1.1% of the applied dose at 0 h to 24.1% at 12 h, 34.2% at 24 h and finally to 37.6% of dose after 48 h of exposure. In view of the high target organ levels of the compound maintained over days, its rapid appearance in the stratum corneum after application and the earlier finding that Sertaconazole nitrate is not distributed into blood in substantial quantities the pharmacokinetic properties of this antifungal preparation therapy can be regarded as favourable.