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RESEARCH PRODUCT

Effects of polysorbate 80 on amiodarone intestinal absorption in the rat

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Abstract Amiodarone is a widely used anti-arrhythmic agent which shows physico-chemical properties that are highly suitable for diffusion across lipophilic absorbing membranes, however,.its low aqueous solubility could represent the rate-limiting step for absorption, making it erratic and variable. In a previous paper, the influence of an anionic surfactant (sodium lauryl sulphate) at variable supramicellar concentrations was studied. The absorption rate constants of amiodarone decreased as the surfactant concentration increased, and absorption was unusually fast at lower surfactant concentrations. The previously proposed equations for interpreting the relationships between the amiodarone absorption rate constant and sodium lauryl sulphate concentration in the intestinal lumen are extended here to the absorption of the drug in the presence of a non-ionic surfactant (polysorbate 80) at different supramicellar concentrations (from 0.4 to 80 mM). In the same way, a modification of the previously reported equations for quantifying the absorption of micellized drug through the intestinal membrane is described. This modification has been applied to the results obtained for both surfactants, but does not improve the previously postulated biophysical model.