Studies On Liposomal Formulations Of Topotecan Hydrochloride

Topotecan, a water-soluble analogue of camptothecin. Preclinical studies showed that, it has demonstrated a broad spectrum of antitumor activity by inhibiting topoisomerase I of DNA which ultimately results in fragmentation of DNA. It was studies in patients with ovarian carcinoma, non-small cell lung and large intestine cancer in phase II studies. And it was approved by FDA on May 29th 1996 to treat patient with advanced drug-resistent ovarian carcinoma and non-small cell lung cancer follow.Topotecan can be administrated by i.v., i.m., i.p. and oral. It’ s disadvantages are acute toxicity, mainly neutropenia and leucopenia, and incidence are both about 97%. Here we are trying to reduce its adverse reacts, prepared topotecan hydrochloride liposome by ammonia sulfate gradient, and for enforce its stability, we coated it with chitosan hydrochloride and lyophilize it.We developed RP-HPLC method to determine the drug concentration, aparted liposome and free drug by ultrafiltration, and founded the method to determine the encapsulation efficiency of liposomes. And we also founded method to study in vitro release profile of the liposomes.Aimd at high encapsulation efficiency, we optimized the formulation compose of plane liposome, and got the optimist formulation compose with very high encapsulation efficiency. And for improving its stability, we coated it with chitosan hydrochloride, considered that it could stabilize the liposome and could be drunk. We preliminary checked the physics and chemical properties of plane and chitosan coating liposme. And the results showed that coated with chitosan couldn’ t improve the liposome stability, but can effect protect degradation of liposome and leakiness of the contents of liposme against acid entironment.For improving the stability of plane lipsome, we lyophilized it. And examined different item and concentration of lyoprotectants on the appearance and size distribution of the rehydrate liposome. Optimized the formulation by single and orthogonal design, and got the optimist formulation, and it had good appearance, loosen, porous, easy to rehydrate and the encapsulation efficiency was more than 80%.Deeply examined the properties of rehydrate lyophilized proliposome, and the results showed that it can be rehydrate easily, had no significant between on its size before and after rehydrate. Its zeta potential was -2.2mV, encapsulation efficiency was 82.29 + 0.35 %. The result of in vitro release showed that, the rate of the drug release from rehydrate liposme was faster than non-freeze drying liposme, but the rate was still very slow.The results of stability test showed that freeze drying topotecan hydrochloride proliposome was sensitive to high temperature and hard light. And the results accelerate and room temperature stability test showed that after the test the freeze drying cake had no significant change except little decline of encapsulation efficiency. So we concluded that its stability was good. Biological safety test show that the rehydrate liposome was asepsis and pyrogen free, and had no obvious stimulation.