title: [Determination of liposome/water partition coefficients of salmeterol and budesonide and study on their influencing factors].
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, China. wangzx75@yahoo.com.cn
authors.forename: Zhi-xuan
authors.initials: ZX
authors.lastname: Wang
authors.forename: Ying-jie
authors.initials: YJ
authors.lastname: Deng
authors.forename: Xiao-peng
authors.initials: XP
authors.lastname: Zhang
mesh_terms: D000420:Albuterol / Q000031:analogs & derivatives* / Q000737:chemistry; D019819:Budesonide / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry; D004337:Drug Carriers; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008081:Liposomes; D008567:Membranes, Artificial; D010743:Phospholipids / Q000145:classification; D000068299:Salmeterol Xinafoate; D014867:Water / Q000032:analysis
chemical_list: D004337:Drug Carriers; D007477:Ions; D008081:Liposomes; D008567:Membranes, Artificial; D010743:Phospholipids; D014867:Water; D019819:Budesonide; D000068299:Salmeterol Xinafoate; D002784:Cholesterol; D000420:Albuterol