Pharmacokinetics of intravenous ranitidine and its effect on gastric acid secretion stimulated by pentagastrin in the cirrhotic

: The pharmacokinetics of 50 mg intravenous ranitidine and the consequences on pentagastrin (2 micrograms/kg/h)-stimulated gastric acid secretion were studied in ten cirrhotic patients. Group I (n = 5) included patients without ascite; group II (n = 5) was characterized by the presence of ascites. Blood creatinine was normal in all the subjects. In non-ascitic cirrhotic patients, pharmacokinetic parameters are similar to those published in healthy subjects. In group II ascitic cirrhotic patients, the half-life is significantly increased by 50 p. 100 (P less than 0.05), as compared to group I, due to a 38 p. 100 decrease of total clearance and to a 45 p. 100 decrease of renal clearance (P less than 0.05). Hepatic clearance and volume of distribution are similar in both groups. The percentage of the inhibition by ranitidine of pentagastrin-stimulated acid out-put, in 6 cirrhotic patients, is 95 +/- 4 p. 100 (SD) when measured at the maximal inhibition peak, and 71 +/- 4 p. 100 (SEM) on the average, during the 3 h following the injection. In conclusion, ranitidine may be considered as an effective anti-secretory drug in cirrhotic patients; the pharmacokinetic variations observed in ascitic cirrhotic patients are the result of the decrease of ranitidine renal clearance.