Sterically stabilized liposomes with saturated lipid as the major lipid component (DSPC:m-PEGDSPE were applied in DB-67 delivery. The drug retention in vitro and pharmacokinetic properties in vivo were investigated. Liposomal DB-67 was cleared faster from the circulation in the larger liposomes (~180 nm) than in the smaller ones (~120 nm), even though DB-67 was retained longer in smaller size liposomes in vitro. Liposomal DB-67 clearance was increased when cholesterol was present in the liposomal composition (40 mole %). It can be attributable to the faster drug release from cholesterol containing liposomes as compared to liposomes without cholesterol. Cholesterol free liposomes with smaller particle size (~120 nm) were chosen as the optimal formulation. In addition, high lipid doses led to the lower clearance of liposomal DB-67 because the liposomal carriers were retained in the circulation longer. Liposomes of larger particle size were taken up by the liver and spleen to a greater extent than the smaller ones. But cholesterol content and lipid dose did not alter the tissue uptake of liposomes. The area under the DB-67 plasma concentration-time curve (AUC) for liposomal DB-67 was 40-fold higher that for non-liposomal DB-67
