Pharmacokinetics of ranitidine in geriatric patients with multiple diseases

Ranitidine pharmacokinetics was measured after intravenous administration of 50 mg of the drug in 18 geriatric patients suffering from multiple diseases. Elimination half-life was prolonged (3.05 +/- 0.58 h) and total clearance was reduced (282 +/- 97 ml/min) as compared to the results of studies on normal younger persons by other investigators. In comparison to other studies on healthy elderlies, the pharmacokinetic parameters of ranitidine were only slightly different. Statistical analyses showed correlations of pharmacokinetic parameters of ranitidine with creatinine clearance, serum creatinine, uric acid concentration and alkaline phosphatase activity. These results disclose that reduced creatinine clearance or serum creatinine concentration in the upper normal range, for example, might serve as indicators for a possible dose reduction of ranitidine to prevent unnecessary overmedication in elderly patients.