Plasma propranolol concentrations in rats with adjuvant-induced arthritis

Previous work has shown that after a single oral dose, plasma propranolol concentrations in patients with active inflammatory disease are significantly higher than those in healthy subjects. After oral administration of propranolol (2 mg) to arthritic rats, the area under the mean drug concentration-time curve in plasma was approximately 10 times greater than that in control animals. After intravenous administration (0.25 mg) the area in arthritic rats was approximately doubled compared with that in controls. The mechanisms causing these changes are not known, but it is probable that increased drug binding to an acute phase reactant in plasma, together with decreased first-pass hepatic clearance in arthritic rats after oral dosing, are involved.