Tamoxifen citrate encapsulated sustained release liposomes: preparation and evaluation of physicochemical properties

The present study was designed for the development of a stable sustained release liposomal drug delivery system for tamoxifen citrate (TC) using soya phosphatidylcholine (SPC), cholesterol (CH) and span 20 as main ingredients. Liposomes were prepared by formation of thin lipid film followed by hydration. The mean vesicle diameter was found to be 203.5 Â 19.5 nm with 21% of the liposomal population having average diameter below 76.72 Â 6.7 nm. There was a good vesicular distribution with the polydispersity index of 0.442 Â 0.03. The maximum loading of drug was determined to be 53.60% of the initial amount that is 34.58 Îg of drug per mg of lipid. Amongst the different storage conditions, liposomes stored at 2â8ÂC were found to be most stable and only 4% of the drug was lost over the storage period of 5 weeks. In vitro release studies of liposomes showed that 50% of drug was released within 3 hours (h) whereas 95% drug was released in 30 h. This indicates the usefulness of the liposomal delivery system for sustaining the in vitro release of tamoxifen citrate.