Possible Interaction: Ethanol and Warfarin

“For example, a 73-year-…/100 mm Hg who takes warfarin (time in therapeutic range [TTR] 40%) (i.e., poor INR … events) and excessively uses nonsteroidal antiinflammatory drugs (NSAIDs) and alcohol might be assigned an ORBIT score of 0 (low …) but a HAS-BLED score of 5 (high risk).”

“Other important risk factors that influence the incidence of warfarin-induced bleeding complications … bleeding for every decade of age above age 40 [5]; drug interactions and ethanol … warfarin effects; and duration of anticoagulationgastrointestinal and genitourinary bleeds, which occur most …, are uncommonly fatal, andmay be because of concurrent anatomic lesionsormalignancies.”

“Caution should be used whenever warfarin and alcohol in any amount are taken together, especially in patients receiving many drugs, and close monitoring of the INR is warranted.”

“In addition, numerous drugs, certain dietary supplements, alcohol , and even some foods markedly influence warfarin dose response.”

“Older age (>or=85 years), younger age (<55 years), prior intracranial hemorrhage, prior gastrointestinal hemorrhage, predisposition to falls, alcohol or other drug abuse, renal impairment, and conditions perceived as barriers to compliance predicted decreased warfarin use.”

“Several factors, including alcohol or other drug abuse or dependence, psychiatric disease, homelessness or inadequate housing, and lack of a caregiver, were highly prevalent and seemed to bias against warfarin prescribing.”

“Ethanol effects on warfarin binding to human serum albumin (HSA) have been studied by equilibrium dialysis and … 7.4 in phosphate-buffered saline at 37 degrees C. In the presence of various amounts of ethanol … warfarin decreased significantly but this intensity reduction was … displacement of bound warfarin from HSA.”

“The dissociation constant of warfarin binding to HSA decreased with an increasing amount of ethanol.”

“Numerous classes of prescription medications can interact with alcohol , including antibiotics, antidepressants, antihistamines, barbiturates, benzodiazepines, histamine H2 receptor antagonists, muscle relaxants, nonnarcotic pain medications and anti-inflammatory agents, opioids, and warfarin.”

“Case 2-A 54-year-old man on long-term warfarin for a prosthetic mitral valve took an overdose of 300 mg of warfarin together with alcohol.”

“Highly bound drugs with low intrinsic hepatic clearance are among the most commonly reported to have their kinetics altered by ethanol (e.g. benzodiazepines, phenytoin, tolbutamide and warfarin).”

“The rates of elimination of zoxazolamine and warfarin from the circulation were significantly reduced in rats fed ethanol 2 hr before.”