IR and X-ray diffraction study of chlorpheniramine maleate-montmorillonite interaction

As a contribution to studies on the adsorption of drugs by clay minerals aimed at achieving sustained action in the oral administration of antihistamines, the adsorption of chlorpheniramine maleate by sodium montmorillonite was studied by X-ray diffraction and IR spectroscopy. The results indicated that the chlorphenirammonium ion penetrated into the interlayer space of montmorillonite, producing an increase in the basal spacing, d001, of the silicate. This increase was influenced, as was the amount adsorbed, by the pH and the concentration of the chlorpheniramine maleate solution. At pH 7.0, the amount adsorbed was close to the exchange capacity, and the complex formed had a basal spacing of 17.14 A (delta = 7.54 A). The only mechanism responsible for the interaction was cation exchange. The complex at 17.14 A must be a monolayer with the benzene rings positioned perpendicular to the surface of the oxygen atoms.