Abstract

Semi synthetic phospholipid, dipalmitoylphosphatidylcholine, with or without cholesterol was used to study the encapsulation efficiency of diclofenac sodium into liposomes as well as to investigate its retention into liposomes. To improve encapsulation efficiency of diclofenac sodium into liposomes, natural phospholipids from Triticum sp. (wheat germ) and chitosan for coated liposomes were used. Diclofenac sodium was encapsulated into uncoated and coated liposomes using the thin film hydration method, with an efficiency of more than 90 %. Improvement in the encapsulation efficiency of diclofenac sodium into liposomes, was achieved by employing phosphatidylethanolamine, dicetyl phosphate and chitosan. The encapsulation efficiency reached a maximum when liposomes were prepared from Triticum sp. lipids and was 99 % compared to 59 % when dipalmitoylphosphatidylcholine was used. Results showed that the presence of cholesterol in the dipalmitoylphosphatidylcholine liposome bilayers produced a significant decrease in the encapsulation efficiency of diclofenac sodium. Chitosan-coated liposomes (dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylcholinelcholesterol and Triticum sp. lipids) were prepared, and their encapsulation efficiency was studied. Encapsulation efficiency was affected by chitosan-coating, due to the presence of dicetyl phosphate rather than the presence of chitosan. The release of encapsulated diclofenac sodium from uncoated and coated liposomes in pH 7.4 normal saline at 37° was studied and DSC technique was employed to explain the results from drug release and the influence of cholesterol into uncoated liposome bilayers.