Effect of fatty acids and alcohols on the penetration of acyclovir across human skin in vitro.

The cutaneous penetration of acyclovir can be significantly increased from a propylene glycol base vehicle by adding small amounts of a polar lipid such as oleic acid. These results are consistent with those found for salicylic acid, and the large increases in acyclovir penetration could potentially lead to better topical treatment of herpes simplex.