Topical delivery of different acyclovir palmitate liposome formulations through rat skin in vitro.

The objective of this investigation was to examine the permeation of acyclovir palmitate from various liposome formulations through hairless rat skin in vitro. The penetrated amount, permeability and intradermal retention of ACV-C16 were compared among various lipid compositions and different vesicle charges. We found that all of the liposome formulations resulted in higher flux and permeability of ACV-C16 than a common ointment form. The 'skin lipid' liposome provided the most effective transdermal delivery of incorporated ACV-C16. Presence or absence of cholesterol in the lipid bilayers did not reveal any difference in transdermal delivery of the associated ACV-C16. Intradermal retention of ACV-C16 from positive liposomes was significantly higher than that from other formulations. These findings suggested that liposomes itself might not penetrate through the skin, but enhance the transfer of incorporated ACV-C16. Liposomal lipid composition was the most important factor affecting the efficiency of transdermal delivery of incorporated drugs, but was not correlated with its phase transition temperature.