Ranitidine disposition and systemic availability in hepatic cirrhosis

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Abstract
Single-dose ranitidine [an antigen drug] kinetics were studied in 10 patients with cirrhosis as proved by liver biopsy. All were clinically stable. After an overnight fast, ranitidine was given in a randomized crossover order as a bolus i.v. injection (50 mg) or was taken by mouth (150 mg). Terminal t1/2 [half life] was 2.7 .+-. 0.4 h after oral dosing and 2.9 .+-. 0.4 h after i.v. injection. Total plasma clearance was 470 .+-. 170 ml/min and the steady-state volume of distribution was 1.2 .+-. 0.2 l/kg. There was considerable intersubject variability in the raitidine serum concentration-time profile after oral dosing. Systemic availabilty as assessed by AUC [area under the plasma concentration time curve] analysis was 58 .+-. 11%. Not all of the dose could be recovered in the urine as unchanged ranitidine and its known metabolites after i.v. injection. At 0.5 .mu.g/ml the serum protein binding of ranitidine was 4.6 .+-. 1.3%. Evidently disposition of ranitidine in these 10 stable subjects with cirrhosis was not significantly altered. The minor changes observed in some were as likely to be the result of secondary perturbations in physiologic status as to effects of cirrhosis on drug metabolism.