TEAR-INDUCED RELEASE OF LIPOSOME-ENTRAPPED AGENTS

The potential use of liposomes for the ocular delivery of entrapped substances appears promising, but very little is known about the possible effect of tear fluid on the stability of liposomal preparations. In this study, we have continued our investigations of tear-mediated release of liposome-encapsulated agents with the aim of developing a biocompatible carrier for topical ocular applications. Rabbit tear fluid was shown to promote the release of both an entrapped water-soluble dye (5-carboxyfluorescein) and a high molecular weight protein (acetylcholinesterase) from multilamellar liposomes. Heat treatment of tear fluid was found to have no effect on the release of the enzyme but did reduce dye leakage. Pre-incubation of the tear fluid with empty liposomes was found to have no significant effect on either enzyme or dye release. Unlike serum where liposome destabilization is reportedly almost entirely the result of high density lipoproteins, our results suggest that multiple factors are involved in tear-mediated liposome destabilization. © 1990.