ABSTRACT
The adsorption of phenethylamines (dextroamphetamine, phentermine, mephentermine, diethylpropion), choline, and phenylimidazoles (levamisole and imazalil) was examined in vitro in aqueous solutions on bentonite and on lewatite at 25 degrees C. An ion-exchange mechanism prevails for lewatite and for bentonite up to 0.8 mEq X g-1. The organic cations are more strongly adsorbed on bentonite than on lewatite. On bentonite, the selectivity of adsorption follows the order: primary less than secondary less than tertiary phenethylamines. An interlamellar monolayer is formed. All drugs, except choline and imazalil, are adsorbed in excess of the cation exchange capacity of bentonite without observable Cl- adsorption and pH changes. Desorption is reversible for lewatite and partially irreversible for bentonite.
