Immobilized liposome chromatography to study drug–membrane interactions: Correlation with drug absorption in humans

For rapid screening of drug–membrane interactions and predicting drug absorption in vivo, unilamellar liposomes were stably immobilized in the pores of gel beads by avidin–biotin binding. Interactions of a diverse set of well-described drugs with the immobilized liposomal membranes were reflected by their elution profiles. The membrane partitioning coefficients (KLM) of the drugs were determined from the retention volumes. The drug retentions on egg phosphatidylcholine (EPC)–phosphatidylserine (PS)–cholesterol (chol) and EPC–PS–phosphatidylethanolamine (PE)–chol columns intended to mimic small intestine membranes were similar, although the positively-charged drugs were more strongly retarded on the negatively-charged liposomes than the negatively-charged drugs. The relationship between log KLM with the drug fraction absorbed in humans showed that the log KLM values obtained with unilamellar liposomes can be used to predict drug passive transcellular absorption, similarly to that previously shown for entrapped multilamellar liposomes. The immobilized liposome chromatography method should be useful for screening compounds at an early stage of the drug discovery process. The avidin–biotin immobilization of the liposomes prolongs the lifetime of the columns.