SWELLING OF AND DRUG-RELEASE FROM MONOGLYCERIDE-BASED DRUG-DELIVERY SYSTEMS

Depending on the water content, unsaturated monoglycerides form variou s liquid crystalline phases, which can be used as sustained-release ca rriers. The aim of this study was to investigate the water uptake of a nd drug release from melt-congealed monoglyceride-based drug carriers. The water uptake of the unsaturated monoglycerides monoolein and mono linolein followed second-order swelling kinetics and levelled off at a bout 50% water content, at which a highly viscous cubic phase was form ed. The rapid formation of the cubic phase suggested that the drug rel ease occurred mainly from this phase. The drug release followed the sq uare-root of time relationship during the initial release phase. Chlor pheniramine maleate, an amphiphilic drug was not completely released b ecause of binding to the cubic phase. The rate of water uptake increas ed and the maximum water uptake decreased with increasing temperature. The drug release could be controlled by varying the surface-to-volume ratio, the drug loading, and the water content of the lipid matrix. I t was independent of the source of monoolein.