Acyclovir-containing liposomes for potential ocular delivery Corneal penetration and absorption

The in vitro corneal penetration and in vivo corneal absorption of acyclovi r from an acyclovir-containing liposome system were investigated, Results o f in vitro corneal penetration demonstrated that positively charged liposom es resulted in a penetration rate lower than those of negatively charged li posomes and free acyclovir in solution. An in vivo study indicated that the extent of acyclovir absorption from positively charged liposomes was highe r that those from negatively charged liposomes and free acyclovir. The acyc lovir concentration in the col nea after administration of positively charg ed liposomes showed that an acyclovir deposition in the cornea was greater than those of negatively charged liposomes and free acyclovir. From morphol ogical observation of the cornea surface treated with liposomes, it was sug gested that positively charged liposomes formed a completely coated layer o n the cornea surface. These liposomes would bind intimately on the cornea s urface, leading to an increase of residence time. Therefore, positively cha rged liposomes resulted in an increase of acyclovir (ACV) absorption. (C) 2 000 Elsevier Science B.V. All rights reserved.