Comparison of Dialysis and Dispersion Methods for In Vitro Release Determination of Drugs from Multilamellar Liposomes

The aim of these studies was to compare dialysis and dispersion methods for determining in vitro release of propranolol, metoprolol, pindolol, and atenolol from multilamellar liposomes.Multilamellar vesicles (MLV) were prepared using hydrogenated soy-lecithin phospholipon 90H (Ph 90H) as the primary lipid.The same volume of pH 7.4 phosphate buffered saline was used as a receptor medium for both methods.Samples were withdrawn, and drug concentration was determined using HPLC.All drug-containing liposomes exhibited an initial burst release followed by a slower rate of release.The rate and extent of drug release from MLV was dependent on the physicochemical properties of the drug.For all drugs investigated, the rate of release was higher for the dispersion method as compared with the dialysis method.