Influence of acute viral hepatitis on disposition and pharmacologic effect of warfarin

Five patients received a small oral dose of warfarin during and after recovery from acute viral hepatitis. Mean (+/- SD) clearance, volume of distribution, and half-life of the drug were 6.1 +/- 0.9 ml/hr/kg, 0.09 +/- 0.04 L/kg, and 23 +/- 5 hr, respectively, during the acute period. After apparent recovery, observed values were 6.1 +/- 0.7 ml/hr/kg, 0.21 +/- 0.02 L/kg, and 25 +/- 3 hr. These differences were not significant. Pattern of renal elimination of warfarin metabolites and drug protein binding did not change between the two phases. During the acute period of illness, prothrombin time increased in 2 of the 5 subjects, but remained within normal limits in all participants during the recovery period. This study shows that warfarin disposition may not change as a consequence of mild or moderate hepatic impairment.