Drug-induced hepatic injury

Drugs and other chemical toxins account for less than 5% of cases of jaundice or acute hepatitis and fewer cases of chronic liver disease, but they are an important cause of more severe types of hepatic injury. Drug reactions produce an array of hepatic lesions that mimic all known hepatobiliary diseases; this poses a diagnostic challenge for physicians and pathologists. Diagnosis of drug-induced hepatic injury is circumstantial, with positive rechallenge bring the only factor that unequivocally implicates a particular agent. Nonetheless, other aspects of the temporal relationship between drug ingestion and adverse reaction, exclusion of other diseases, the presence of extrahepatic features of drug hypersensitivity and same findings on liver biopsy can lend support to the diagnosis. Some of these issues will be explored in this review by considering contemporary paradigms of drug-induced hepatic injury. Factors that predispose to dose-dependent hepatic injury will be considered in relation to acetaminophen, an example of acute hepatotoxicity and methotrexate, an agent that can produce hepatic fibrosis. Flucloxacillin will be discussed as an example of drug-induced cholestatic hepatitis often associated with prolonged cholestasis and the vanishing bile duct syndrome. Minocycline and diclofenac will be mentioned as two drugs for which drug hepatitis is an exceedingly rare complication. Finally, the evidence that Chinese herbal medicines can be hepatotoxic will be reviewed.