Investigation of permeation of acyclovir through skin using alaptide

The investigation deals with the affection of the permeation of acyclovir through full-thickness pig ear skin using a Franz diffusion cell from the donor vehicles of phosphate buffer (pH 7.4) and propylene glycol–water (1:1) using synthesised (S)-8-methyl-6,9-diazaspiro[4.5]decane-7,10-dione, alaptide as a transdermal permeation enhancer. Alaptide was applied in ratio 1:10 (w/w) relative to the amount of acyclovir. At the first hour after application, the permeated amount of acyclovir from propylene glycol–water system, simulating semisolid dosage forms, was ca. four-fold higher than from the formulation without alaptide. Despite that the enhancement ratio of alaptide in a steady state was 1.7, the pseudo-enhancement ratio of alaptide in the time range of first to third hour was 2.3. Both enhancement ratios indicate that alaptide modifies skin structure, while the short-term application of the alaptide formulation seems to be more advantageous.