Skin irritation and the inhibition effect on HSV-1 in vivo of penciclovir-loaded microemulsion.

The purpose of the present study was to investigate the skin irritation and pharmacodynamics of penciclovir-loaded microemulsion (PCV-ME). The formulation of PCV-ME was comprised of oleic acid (OA) (5%, w/w), Cremorphor EL (20%, w/w), ethanol (30%, w/w) and water (45%, w/w). PCV-ME presented as spherically shaped under transmission electron microscopy with an average diameter of 36.5 nm, and the solubility of PCV in microemulsion (ME) was 7.41 mg/g, almost 6 times that in water. Skin irritation test was performed in male guinea pigs, which demonstrated that no irritation effect was caused after single or multiple applications of PCV-ME. Likewise, male guinea pigs were employed as animal models which were infected with herpes simplex virus type 1 (HSV-1) in pharmacodynamics study. Real-time PCR was utilized to investigate the inhibition effect on HSV-1 exerted by commercial PCV-cream and PCV-ME. The results indicated that compared with commercial PCV-cream, PCV-ME could significantly inhibit the replication of HSV-1 in skin. In conclusion, PCV-ME could be a promising formulation which possessed the virtues of low irritation and high effectiveness.