Pharmacokinetics and bioavailability of ranitidine in normal subjects and cirrhotic patients.

Pharmacokinetic parameters of ranitidine were determined comparatively in nine cirrhotic patients and eight healthy volunteers after administration of a single oral (150 mg) or intravenous dose (50 mg). Bioavailability was virtually the same in patients and in normal subjects, and there was no significant difference between the two groups for total plasma clearance, intravenous elimination half-life, or volume of distribution. The mean maximum plasma concentration was 43% higher in patients than in volunteers, but the difference was not significant. The values for the kinetic parameters did not significantly differ between patients with and without ascites or with and without hepatocellular insufficiency. These results indicate that ranitidine kinetics are not appreciably altered in cirrhotic patients and that reduction of dosage is not required in such patients unless their renal function is impaired.