Examination of the chloroquine-kaolin drug absorption interaction using the buccal partitioning model.

Recently, an in vivo model of drug interaction in the intestine, involving buccal absorption, has been suggested. The present work evaluates this experimental model system using chloroquine and kaolin. Kaolin was found to decrease chloroquine partitioning into the buccal membranes in three healthy volunteer subjects. This deminished absorption reflected the fact that chloroquine bioavailability after oral dosing has recently been shown to be decreased by kaolin. These findings support the use of buccal partitioning as a screening device for drug interactions occurring by adsorption or complexation in the intestine. The present interaction most likely takes place due to adsorption of the drug on to the antidiarrhoeal agent. This is likely to decrease the effectiveness of chloroquine as an anti-rheumatic or anti-malarial drug if taken together with kaolin.