Determination of the stereoselectivity of chiral drug transport across Caco-2 cell monolayers |
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Authors: | He Ying Zeng Su |
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Affiliation: | College of Pharmaceutical Sciences, Department of Pharmaceutical Analysis and Drug Metabolism, Zhejiang University, Hangzhou, P.R. China. |
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Abstract: | This study aimed to determine the transport characteristics of chiral drug enantiomers across Caco-2 cell monolayers as a model of human intestinal epithelial membrane. Esmolol was chosen as a model drug, and the study focused on the transepithelial transport of esmolol enantiomers in this in vitro model system. Separation and quantitation of (S)- and (R)-esmolol were performed by RP-HPLC with the use of GITC as a precolumn derivatizing agent. Bidirectional transport studies of 5.0-400.0 micromol/l esmolol demonstrated that the two enantiomers were transported mainly by a passive, transcellular mechanism. At concentrations of 5.0-100.0 micromol/l, enantioselective permeability of esmolol was observed. In the absorptive transport, Papp of (S)-esmolol was smaller than (R)-esmolol and vice versa for secretory transport. The enantioselectivity disappeared when the drug concentration was increased to 200.0 micromol/l. In conclusion, the transport characteristics of (S)- and (R)-esmolol were distinctly different. An enantioselective carrier-mediated mechanism in addition to passive diffusion was involved in the transport process of esmolol across Caco-2 cell monolayers. |
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Keywords: | esmolol transport permeability enantioselectivity carrier‐mediated mechanism |
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