POLYMER-COATED LIPOSOMES - STABILITY AND RELEASE OF ASA FROM CARBOXYMETHYL CHITIN-COATED LIPOSOMES

Liposomes of dipalmitoylphosphatidylcholine (DPPC) were coated with carboxymethyl chitin (CM-chitin), a water-soluble polysaccharide, either during the formation of reverse phase evaporation vesicles (REVs) or using preformed REVs. Acetylsalicylic acid (ASA) encapsulation efficiency was not affected by the polymer coating. Liposomes coated with CM-chitin during processing were more stable in sodium cholate solutions and yielded significantly lower release rates of ASA than preformed liposomes coated with CM-chitin or uncoated liposomes. The release rate reached a minimum when liposomes were coated from a 1% CM-chitin solution and was approximately one-third of that obtained from uncoated liposomes. Thus, these improvements in liposome behaviour may be beneficial for the oral administration of drugs.