Drug-induced hepatotoxicity: 2005

The removal from the marketplace of several widely prescribed drugs due to hepatotoxicity has attracted considerable attention. Now under extensive review are means by which we can better identify hepatic risk prior to federal approval. Assessment of risk-to-benefit ratios regarding a novel agent with hepatotoxicity issues (especially one for a life-threatening condition) requires considerable judgment and education on the part of prescribers and patients. The spectrum of drug-induced liver injury is broad with simulation of almost all unknown liver disorders. Drug-induced liver injuries often have a somewhat characteristic signature, as regards type of injury (hepatocellular vs cholestatic) and time of onset. The diagnosis of drug-induced liver injury is often one of exclusion with initial suspicion based on circumstantial evidence. Factors affecting susceptibility to drug-induced injury include age, sex, concomitant use of other drugs, and genetic polymorphism in metabolic pathways involved in activation or disposition of therapeutic drugs. Drug-drug interactions present particular problems in patients, often elderly, who are receiving several drugs simultaneously. Mechanisms of drug-induced liver injury are many and varied. With many drugs, intermediary products produced during metabolism are highly reactive and toxic. In these situations, the balance between the rate of production of the metabolite and the effectiveness of the drug may determine whether or not hepatic injury occurs.