Characteristics and pharmacokinetics of docetaxel liposome containing Tween 80 or PEG-DSPE

To prepare the two liposomes containing docetaxel, which Tween 80 or 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine [methoxy (polyethyleneglycol)-2000] (PEG2000-DSPE) were used respectively to obtain higher drug-loading efficiency and better stability. Tween 80 was able to enhance the drug-lipid ratio from 0.02 to 0.06 (molar ratio). However, when the molar ratio of Tween 80 to total lipid was lower than 1%, docetaxel would crystal out, which led to the encapsulation efficiency decreasing significantly. The characteristics of the liposomes containing Tween 80 and PEG2000-DSPE were investigated respectively. The mean diameters of the two liposomes were 136 and 126 nm, the x potentials were -7.3 and -18.1 mv, and the encapsulation efficiency determined by ultrafiltration were 98.6 and 99.3%, respectively. All the characteristics remained virtually unchanged after freeze drying. The in vitro release of PEGylated liposome was slower than that of liposome containing Tween 80. The pharmacokinetic in rats showed that the PEGylated liposome displayed a sustained release character and longer circulation time in vivo compared with liposome containing Tween 80, with an increased t1/2β 151.9 min, AUC0œ 2186.1 mg/Lmin, against t1/2β 50.4 min, AUC0œ 577.4 mg/Lmin.