Moderate
Probable
Description
Carbamazepine induces CYP enzymes that convert acetaminophen to its hepatotoxic metabolite NAPQI, increasing the risk of acetaminophen-induced liver injury even at therapeutic doses.
Mechanism
Carbamazepine strongly induces CYP2E1 and CYP3A4, shifting acetaminophen metabolism away from glucuronidation toward the reactive NAPQI pathway; concurrent depletion of hepatic glutathione stores worsens toxicity risk.
Clinical Significance
Case reports document hepatotoxicity in patients on carbamazepine taking recommended doses of acetaminophen; the therapeutic window is narrowed.
Management
Use the lowest effective acetaminophen dose, avoid prolonged use, and counsel patients to abstain from alcohol; consider alternative analgesics where possible.