Abstract: | ‘In vitro’ and ‘in vivo’ studies were used to determine the interaction of naproxen, an anti-inflammatory agent, and cholestyramine, a hypocholesterolemic substance. Cholestyramine shows a marked affinity for naproxen and the intensity of this is governed by the pH values. The maximum amount of naproxen adsorbed by the resin is close to 2·2 mMg?1. The pharmacokinetics of naproxen was studied in eight healthy volunteers after concurrent oral administration in a single dose of 250 mg of naproxen and 4 g of cholestyramine. The resin causes an important delay in the incorporation of naproxen into the systemic circulation, though no significant modifications are seen to take place in any other pharmacokinetic parameters of the drug. |