ANTACIDS OR FOOD CAN DELAY AND DECREASE THE ORAL ABSORPTION OF ACETAMINOPHEN. PHENOTHIAZINES CAN INTERFERE WITH THERMOREGULATION. CONCOMITANT USE OF ACETAMINOPHEN WITH PHENOTHIAZINES CAN PRODUCE HYPOTHERMIA IF ACETAMINOPHEN IS GIVEN IN LARGE DOSES. THE RISK OF DEVELOPING HEPATOTOXICITY FROM ACETAMINOPHEN APPEARS TO BE INCREASED IN PATIENTS WHO REGULARLY CONSUME ETHANOL. AGENTS WHICH INDUCE THE HEPATIC ISOENZYMES CYP2EI AND CYP IA2 LIKE BARBITURATES, CARBAMAZEPINE, CIMETIDINE, ISONIAZID, PHENYTOIN, RIFAMPICIN MAY POTENTIALLY INCREASE THE RISK FOR ACETAMINOPHEN-INDUCED HEPATOTOXICITY VIA GENERATION OF A GREATER PERCENTAGE OF ACETAMINOPHEN'S HEPATOTOXIC METABOLITES. AGENTS WHICH INDUCE ONE OR BOTH OF THESE ENZYMES INCLUDE CARBAMAZEPINE, BARBITURATES, ISONIAZID, PHENYTOIN, RIFAMPICIN, AND RITONAVIR. SULFINPYRAZONE CAN INDUCE HEPATIC MICROSOMAL ENZYMES THAT METABOLIZE ACETAMINOPHEN AND THIS, IN TURN, MAY INCREASE THE RISK OF ACETAMINOPHEN HEPATOTOXICITY DUE TO THE FORMATION OF INCREASED AMOUNTS OF TOXIC ACETAMINOPHEN METABOLITES. USE OF ACETAMINOPHEN PRIOR TO 72 HOURS OR CONCURRENTLY WITH BUSULFAN MAY RESULT IN DECREASED CLEARANCE OF BUSULFAN DUE TO ACETAMINOPHEN-INDUCED DECREASES IN GLUTATHIONE LEVELS. ACETAMINOPHEN PLASMA CONCENTRATIONS CAN INCREASE BY APPROXIMATELY 50% FOLLOWING ADMINISTRATION OF DIFLUNISAL. ACETAMINOPHEN HAS NO EFFECT ON DIFLUNISAL CONCENTRATIONS.