沙美特罗和布地奈德的脂质体/水分配系数测定及影响因素考察

目的测定沙美特罗和布地奈德的脂质体/水分配系数(P_L/w)，考察影响两种药物P_L/w的因素，揭示药物与磷脂双分子层的作用机制。方法用平衡透析法测定两种药物在不同脂质体组成和不同介质中的P_L/w。结果两种药物P_L/w随脂质体中胆固醇含量及磷脂饱和程度增加而减小；脂质体表面负电荷、介质pH值及离子强度增加，沙美特罗的P_L/w增加。脂质体表面电荷、介质pH值及离子强度对布地奈德的P_L/w影响较小。结论药物P_L/w受药物性质、脂质体磷脂种类、饱和程度、胆固醇含量和表面电荷以及介质pH和离子强度等因素影响，在测定时应选择与生物膜环境相近的P_L/w测定条件，以反映药物在生物膜中的分配。

Determination of liposome/water partition coefficients of salmeterol and budesonide and study on their influencing factors

Aim The liposome/water partition coefficients of salmeterol and budesonide between aqueous phase and liposomes were determined and the factors that influence their partition coefficients were studied, the mechanism of interaction between the two drugs and phospholipid bilayer was elucidated. Methods The liposome/water partition coefficients of the two drugs were determined by equilibrium dialysis technique. The change of the partition coefficients of the two drugs along with liposome composition and medium was also studied. Results The partition coefficients of the two drugs decreased with the increase of cholesterol content and saturation of phospholipid used. The liposome/water partition coefficient of salmeterol increased with the increase of liposome surface negative charge, medium pH and ionic strength, while the liposome surface charge, medium pH and ionic strength had no distinct effect on the liposome/water partition coefficient of budesonide. Conclusion The liposome/water partition coefficient of drug was affected by the type, saturation of phospholipid used in liposome preparation, the cholesterol content and surface charge of liposome, as well as the pH and ionic strength of medium also have effect on the liposome/water partition coefficient of drug. Accordingly, in order to reflect the actual partition of drug in biological membrane, the determination condition including liposome composition and medium should be similar to the biological membrane.