Pharmacokinetics of amoxycillin/clavulanic acid in serum and ascitic fluid in cirrhotic patients.

A combination of amoxycillin and clavulanic acid (Augmentin) might be useful for first-line treatment of spontaneous bacterial peritonitis in patients with cirrhosis. We have studied the pharmacokinetics of amoxycillin/clavulanic acid in serum and ascitic fluid of six cirrhotic patients. A total of 66 simultaneous serum and ascitic samples were analysed. Following iv injection of 1 g amoxycillin plus 0.2 g clavulanic acid, the ascites to serum AUC ratio was 1.38 for amoxycillin and 1.01 for clavulanic acid, indicating a good distribution of these drugs into the ascitic fluid. In this study, experimental data were fitted to a three compartment body model which revealed that the prolonged serum half-lives of amoxycillin (274 min) and clavulanic acid (200 min) were probably due to the slow return from the ascitic compartment.