Preparation Of Targeting Cationic Liposomes Of CPT-11 In Lung Modified By D-mannose

Objective: Irinotecan (CPT-11) is a water-soluble camptothecin derivative that has demonstrated clinical activity against colorectal and small cell lung cancers. CPT-11 exerts its cytotoxic effects by stabilizing the covalent intermediate formed between topoisomeraseⅠand DNA. This action prevents the re-ligation of the DNA strand, causing accumulation of DNA- topoisomeraseⅠcomplexes which ultimately leads to apoptosis. This mechanism is dependent on the integrity of the lactone ring common to all camptothecins; However, the lactone ring undergoes a pH-dependent reversible hydrolysis that favours the carboxy derivative at physiological pH. Consequently, drug delivery technologies, including liposomes, have been investigated as a means to stabilise the lactone ring . in general, protection of the lactone ring in these formulations was attributed to partitioning of the drug into the lipid bilayer and/or isolation of the drug within the liposome's interior aqueous compartment that was maintained at low pH. Encapsulating irinotecan in the acidic aqueous core of liposomes, could provides an internal milieu conductive to maintenance of the lactoneform of the drug. These preparations have relied on pH gradients, generated by an ammonium sulfate gradient.D-mannose has the structures of 3,4-OH, could be recognised by the surfactant protein A and D of the lung. If we use D-mannose to modify the surface of the CPT-11 liposomes, there maybe more liposomes foucse on the lung, increased pulmonary targeting. On the other hand, we add some octadecylamine to prescription of liposomes to adjust the surface charge of liposmes increasing the encapsulation efficiency of drugs, but also to prohibit aggregating increasing the stability of liposomes in vitro. For above reasons, we add octadecylamine and D-mannose to the prescription of CPT-11 liposomes so that it could make the drug assemble in pulmonary increasing the therapeutic index, decreasing the rate of adverse reaction.Methods: After reading the relevant literature, we use the ammonium sulfate gradient method to prepare the targeting cationic liposomes of CPT-11 in lung modified by D-mannose. we investigate technology process and factors of formulation to evaluation which could influence the encapsulation efficiency. The EE% was taken as criterion to optimize the quality rate of lipid to cholesterol, the quality rate of drug to lipid, the quality rate of lipid to octadecylamine, the quality rate of drug to D-mannose. On these basis, four factors and three levels orthogonal design was selected to optimize the formula and prepration methods of targeting cationic liposomes of CPT-11 in lung modified by D-mannose. According to analysis of range to finalize irinotecan cationic liposomes best formula and prepration methods.We conducted a preliminary evaluation of the quality and stability of targeting cationic liposomes of CPT-11 in lung modified by D-mannose. Evaluation of quality section includes pH, appearance, size distribution, TEM and cumulative release in vitro of liposome. Evaluation of stability includes the impact of factors in the API study, targeting cationic liposomes of CPT-11 in lung modified by D-mannose of factors and leakage rates study.After reading the relevant literature, the concentration of CPT-11 in mice and rats was determined using a new HPLC system, with scanning fluorescence detector at an excitation wavelength of 375nm and an emission wavelength of 530nm. The separation was achieved by using a Kromasil colum (C18, 250×4.6mm, 5μm), at a rate of 1.0ml/min. The mobile phase consisted of acetonitrile and 0.075mol/L ammonium acetate (1% triethlyamine, pH4.0 adjusted with 36% acetic acid) at a ratio of 30:70(v/v). The injiection volume was 20μl. Results: Through the test of technology process and the orthogonal formulation, we got the best technology process as follows: the volum of ammonium sulfate, 6ml; The concentration of ammonium sulfate, 0.2mol/L; The time of incubation, 45min; The temperature of incubation, 60min; The optimal formulation was as follows: the amount of lipid was 200mg; Cholesterol, 66mg; Octadecylamine, 20mg; mannose, 20mg; CPT-11, 10mg.Stability experiment: API was stability in high humidity and high temperature. In the condition of strong illumination, there was a change in physical appearance. Targeting cationic liposomes of CPT-11 in lung modified by D-mannose had a greater change in the condition of strong illumination and high temperature. There was a amount of precipitation of the yellow lipid.In vitro release test, the percent of cumulative of targeting cationic liposomes of CPT-11 in lung modified by D-mannose was less than 70% after 48h in PBS (pH6.5).The pharmacokinetics study were took in SD rats with the reference of solution of CPT-11 and the AUC were 1.79(μg/ml)?h, 36.03(μg/ml)?h, respectively.The pharmacokinetics study were took in mice with the reference of solution of CPT-11 and the main pharmacokinetics parameters as followed: (?)Conclusion: The particle size distribution of targeting cationic liposomes of CPT-11 in lung modified by D-mannose was concentrated. It could prolong the time of CPT-11 in vitro release test. It was sensitive to light and high temperature, so it should be stored in dark cold condition. The study in SD rats showed that it had a good protection on the lactone ring. The study in mice showed that it could make the drug fouce in the lung.