Studies On Freeze-dried Liposome Of All-trans Retinoic Acid For Injection

The HPLC analytical method for ATRA in vitro was developed. The solubilities of ATRA in water and PBS with different pH and the apparent partition coefficient in n-octyl alcohol/ water was determined by HPLC. The HPLC method for the content of ATRA in liposomes was established. The entrapment efficiency of ATRA liposome was determined by microcolumn centrifuge-HPLC method.The ATRA liposome was prepared by ethanol injection method. The single factor investigation and the orthogonal design were adopted to obtain the optimized prescription, the entrapment efficiency of ATRA liposome was above 95%.To resolve the instability problem of liposome dispersion, freeze-drying (lyophilization) technique was utilized to prepare freeze-dried proliposome. The technology of freeze-dried especially on the kinds and ratio of cryoprotectants had been researched.The physicochemical properties of freeze-dried ATRA liposome were studied. The liposome was spheroidal and uniform, the volume diameters of ATRA liposome suspension and freeze-dried product were (146±19) nm and (170±29) nm respectively , the Zeta potential of these were -(30.9±13.6) mV and-(30.0±18.9)mV separately; the pH value was not changed notably, closed to 7.4; the entrapment efficiency of these were 96.92±0.31% and 94.25±0.52% differently.The results of stability tests indicated that the ATRA freeze-dried liposome was sensitive to high temperature and strong light. There was not significant change in the accelerated test and the long test.The security investigation indicated that the ATRA liposome injection was non-irritant, pyrogen-free and non- hematolytic, the preparation met the regulations of the iv administration.The HPLC method of ATRA liposome in blood plasma and tissues was established. After iv administrated ATRA suspension and liposomes to mice, respectively, the drug concentrations in different tissues were monitored by HPLC. The pharmacokinetic processes in mice for the two preparations were both accorded with two compartmental models. Compared with ATRA suspension, the liposome had longer half-life and higher bioavailability. The levels of ATRA liposome in liver and spleen were higher than that of suspension group.