Studies On The 10-Hydroxycamptothecin Proliposomes

The method of high performance liquid chromatography (HCPT) was set up to determine the concentration of 10-hydroxycamptothecin (HCPT). The apparent solubility of HCPT in distilled water, pH5.0 phosphate buffered saline (PBS), chloroform and octanol were measured, respectively. The apparent partition coefficients of HCPT in octanol/distilled water and octanol/pH5.0 PBS were determined, separately. The time course of carboxylate form of HCPT into lactones form in different pH solutions was also investigated.HCPT liposomes were prepared by thin-film dispersion method, reverse-phase evaporation method, ethanol injection method and pH adjustment method, respectively, we found that the liposomes, which were prepared by thin-film dispersion method, had relatively high entrapment efficiency (EE). The orthogonal design was adopted to obtain the optimized prescription. In order to keep the stability of HCPT liposomes, HCPT liposomes were lyophilized to form proliposomes.Sephadex G-50 filtration chromatography was adopted to separate free drug from HCPT proliposomes after hydration. pH5.0 PBS was used to elute liposomes and then pH12.0 sodium hydroxide solution was applied to dissolve and elute free HCPT. pH12.0 sodium hydroxide solution was added to the HCPT liposomal solution to destroy the structure of liposome and dissolve HCPT, and then chloroform was added to eliminate the lecithoid. The concentration of HCPT in sodium hydroxide solution was determined at wavelength of 420nm and the EE was calculated. The concentration of HCPT in proliposomes was 1.0mg/mL and the EE, 78.5%.The physicochemical properties of HCPT proliposomes were studied. After HCPT proliposomes hydrating, the microphotograph showed that the morphological characteristic of most liposomes was spherical and of single compartment structure, moreover, the pH value was 5.02 and steady with 5%...