Clinical perspectives on xenobiotic-induced hepatotoxicity.

Drug-induced hepatotoxicity is an important cause of liver disease with significant medical, economic, legal, and regulatory implications. Clinically, it presents a diagnostic challenge to health care professionals since drug-induced liver disease can mimic the clinicopathologic features of all other acute and chronic liver diseases. However, individual drugs tend to have a characteristic clinical signature. Early identification of hepatotoxicity by either laboratory monitoring or patients' awareness as a result of education may avert serious liver injury in delayed idiosyncratic toxicity. Most adverse hepatic reactions require metabolism of the drug to reactive metabolites and free radicals, which then either lead to direct overwhelming lethal insult, nonlethal sensitization to the lethal effects of the innate immune system, or haptenization eliciting an immunoallergic response of the adaptive immune system. Besides licensed drugs, herbal and natural supplements are recognized as causing hepatotoxicity with increasing frequency as patients turn more and more to alternative medicine.