Warfarin-acetaminophen drug interaction revisited.
Physicians and pharmacists routinely advise patients receiving warfarin to take acetaminophen for pain or fever because of its relative safety; however, a recent study questioned the safety of such practice. A comprehensive search of MEDLINE and IPA for human studies and case reports from 1966-1999 revealed evidence that acetaminophen may potentiate the effect of warfarin by a mechanism that has yet to be elucidated. Due to lack of a safer alternative, acetaminophen still should be the analgesic and antipyretic of choice in patients taking warfarin, as long as excessive amounts and prolonged administration (> 1.3 g acetaminophen/day for > 2 wks) are avoided. With the high degree of interpatient variability and the unpredictability of various drug-drug interactions with warfarin, close and frequent monitoring of international normalized ratios is the key for safe oral anticoagulation therapy.
Shek
K L
KL
Department of Pharmacy Practice, University of Illinois at Chicago, College of Pharmacy, 60612, USA.
Chan
L N
LN
Nutescu
E
E
D000082:Acetaminophen / Q000378:metabolism / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000378:metabolism / Q000494:pharmacology*; D000925:Anticoagulants / Q000378:metabolism / Q000494:pharmacology*; D002986:Clinical Trials as Topic; D004357:Drug Synergism; D006801:Humans; D010597:Pharmacogenetics; D014859:Warfarin / Q000378:metabolism / Q000494:pharmacology*
D018712:Analgesics, Non-Narcotic; D000925:Anticoagulants; D000082:Acetaminophen; D014859:Warfarin