Abstract

Monoolein dispersions are of great importance as a colloidal drug delivery system due to its unique structure. Thus it was important to measure the drug release from such carrier system. Conventional release methods showed many drawbacks. In an attempt to avoid these drawbacks, the transfer of a lipophilic drug model porphyrin from donor monoolein dispersions into acceptor multilamellar vesicles (MLV) was carried out. The measurement of porphyrin transferred was performed after the separation between the donor and acceptor using a centrifugation technique or directly without separation using a flow cytometric technique. The transfer rate and amount of porphyrin from the donor monoolein vesicles to the acceptor MLV was higher than from monoolein cubic particles. This difference in the rate and amount transferred might be attributed to the sponge like structure of the cubic particles. In addition, the cubic bicontinuous phase has a unique structure with a high specific bilayer/water interfacial area. Additionally, transfer experiments are better than the conventional release methods from the point of similarity to the conditions in the blood. In conclusion, the centrifugation and flow cytometric techniques are suitable techniques to study the transfer from the donor monoolein dispersions to the lipophilic acceptor MLV.