SELECTION OF PHOSPHOLIPID AND METHOD OF FORMULATION FOR OPTIMUM ENTRAPMENT AND RELEASE OF LAMIVUDINE FROM LIPOSOME

Abstract

The present investigation was aimed to compare various phospholipids and different methods that would be appropriate to produce liposomes having vesicle size in the range of 200-300 nm, PDI less than 0.500, maximum entrapment and delayed release of lamivudine. The phospholipids employed were Phospholipon® 90G, Phospholipon® 90H, 1,2-Dimyristoyl-sn-glysero-3-phosphocholine (DMPC) and 1,2-Dipalmitoyl-sn-glysero-3-phosphocholine (DPPC). They were used in various molar ratio with cholesterol and blank liposomes were prepared initially by thin film hydration and ether injection method. The thin film hydration method was only found to be appropriate to produce liposome of desired size and PDI. Hence, the molar ratios of employed phospholipids:cholesterol that produced liposomes as per the expected parameters was then used to load lamivudine. The method of preparation, phospholipid: cholesterol molar ratio, hydrations above transition temperature and hydration time were showed direct influence on vesicle size, PDI, percentage encapsulation and in-vitro release. Phospholipon® 90H: cholesterol: lamivudine in the molar ratio 1:2:1 produced liposomes having desired vesicle size and PDI with maximum drug entrapment and sustained release. The encapsulation efficiency of drug in liposomes was in the order of Phospholipon® 90H> Phospholipon® 90G > DPPC > DMPC.
 Keywords: Liposomes, Lamivudine, Phospholipid, Thin film hydration method, Ether injection method, encapsulation efficiency