M. Sanchez-Camazano, M. J. Sanchez-Martin, M. T. Vicente
A B S T R A C T : The interaction of montmorillonite with sotalol hydrochloride (4-(1-hydroxy-Nisopropylaminoethyl) methane sulfanilide) was studied by means of adsorption isotherms, XRD and IR spectroscopy. The amount of sotalol adsorbed depended on pH, the maximum amount adsorbed (0.56 mEq g-l) being considerably less than the exchange capacity of the mineral (0.80 mEq g-l). XRD and IR data revealed that the sotalol is adsorbed into the interlayer space, forming a monolayer complex with a do01 spacing of 17.7 A, and that the mechanisms involved are cation exchange and ion-dipole interactions. Experiments on the in vitro desorption of the drug from the sotalol-montmorillonite complex indicated that desorption is affected by pH, by the salt concentration of the electrolyte, and by the elimination rate of the desorbed organic cations.