渗透促进剂对多肽类药物肺部给药促渗作用的机理

目的从肺细胞膜流动性的角度探讨渗透促进剂增加多肽类药物肺部吸收的作用机制。方法以鲑鱼降钙素(sCT)为模型药物,考查多种渗透促进剂对sCT经肺吸收的促进作用。采用电子自旋共振(ESR)技术和荧光偏振技术测定旋转相关时间(τ_C)及荧光偏振度(P),计算渗透促进剂处理前后膜脂流动性和膜蛋白构象的变化,从而考查渗透促进剂增加药物肺部吸收的原因。结果可以显著促进药物吸收的苄泽78、卵磷脂、辛酸钠均引起膜脂质流动性的增加,同时造成蛋白构象不同程度的松散;牛磺胆酸钠对膜蛋白的影响较弱;壳聚糖降低膜脂流动性,其促渗作用主要来自于改变了膜蛋白的三级结构而使细胞间紧密连接张力减小;2-羟丙基-β-环糊精对药物吸收没有明显贡献,同时其对膜通透性基本没有影响。结论考查体外细胞膜流动性的变化为研究渗透促进剂对药物肺部吸收的促进作用提供了重要依据。

Study on pulmonary delivery of peptide drugs in rats: effects of absorption enhancers on cellular membrane fluidity

AIM: To study the relationship between cellular membrane fluidity and relative bioavailability (Fr) of protein and peptide drugs combined with absorption enhancers after pulmonary administration in rats. METHODS: A series of model drug salmon calcitonin (sCT) solutions with 6 absorption enhancers (Brij78, sodium cholate, sodium caprylate, 2-hydroxypropyl-beta-cyclodextrin, lecithin and chitosan) were prepared and then delivered to rats by pulmonary route. Serum drug concentration was determined by radioimmunoassay method. Using the techniques of electron spin resonance and fluorescence polarography, the effects of enhancers on pulmonary cellular membrane fluidity were investigated. RESULTS: Fr values of sCT solution with some absorption enhancers (Brij78, sodium cholate, sodium caprylate, lecithin and chitosan) were significantly higher than those without enhancers. Brij78, lecithin and sodium caprylate, not only increased membrane lipid fluidity but also loosed the constitution of membrane protein. The effect of sodium cholate on membrane protein was low. Lipid fluidity was reduced and protein constitution was changed markedly, after pulmonary cellular membrane was treated by 0.5% chitosan solution. This result showed that the absorption enhancing of chitosan mainly came from its effects on membrane protein. Corresponded with lower Fr after pulmonary administration, 2-hydroxypropyl-beta-cyclodextrin (0.5% and 3%) had not significant effects on both lipid fluidity and protein constitution. CONCLUSION: The effects of enhancers on pulmonary absorption of peptide drugs in vivo might be investigated on the grounds of determination of cellular membrane fluidity in vitro.