[Liver injury caused by coumarin anticoagulants: experience of the IKS (Intercanton Monitoring Station) and the SANZ (Swiss Center for Drug Monitoring)].

Drug-induced liver diseases are potentially avoidable. Hepatotoxic drugs can mimic virtually any form of liver disease. Among all voluntary adverse drug reaction reports to central registries, 4-7% refer to drug-induced liver diseases. We analyze all cases of coumarin-induced hepatic injuries reported on a voluntary basis to the Swiss Drug Monitoring Centre (SANZ) and the Pharmacovigilance Centre (IKS) from 1981 to 1995. During this period the SANZ collected 9720 reports, 674 of which (6.9%) referred to the liver and the biliary tract. In only 11 reports an oral anticoagulant was involved. In 8 cases we assumed at least a possible causal relationship. 2 more cases were reported directly to the IKS. Among these 10 cases 7 were related to phenprocoumon and 3 to acenocoumarol. In 4 cases elevated concentrations of liver enzymes were measured 2-7 days after the beginning of therapy. In the remaining 6 cases the clinical picture was so severe that the patients had to be hospitalized. These 10 cases are discussed and compared with the cases published in the literature. According to our data, hepatic disorders induced by coumarin-anti-coagulants are rare. If hepatitis is diagnosed in a patient treated with oral anticoagulants, the differential diagnosis of a coumarin-induced hepatic injury has to be considered. Crossreactions between the coumarin derivatives phenprocoumon and acenocoumarol are possible.