If this is not your name, click here.
| | If this is not your name, click here. | | |
| | Contact Us | Order Now | Journals | Bookstore | Register a colleague | | |
| |  Combining Acetaminophen With Anticoagulant Increases Risk Of Bleeding CHICAGO, IL -- March 3, 1998 -- Prolonged use or high doses of acetaminophen while using the anticoagulant warfarin could substantially increase the risk of bleeding and hemorrhage, according to an article in tomorrow’s issue of The Journal of the American Medical Association. Elaine Hylek, M.D., M.P.H., and colleagues at Massachusetts General Hospital and Harvard Medical School in Boston, MA., interviewed 289 people who had been taking warfarin (a blood thinner) for more than one month to determine the causes of an international normalized ratio (INR) greater than 6.0. By pinpointing the causes of dangerously high INR levels, researchers can help identify those at risk for intracranial hemorrhage, the most feared complication of anticoagulation. The risk for intracranial hemorrhage increases dramatically at INR levels greater than 4.0. The researchers found that people who take 9,100 milligrams of acetaminophen per week (about four regular-strength [325 mg] tablets per day) had a 10-fold increased risk of having an INR greater than 6.0. "Our data suggest that acetaminophen is an underrecognized cause of anticoagulant instability," the authors write. Other risk factors that were associated with an INR higher than 6.0 included new medication known to interact with warfarin, treatment resistance, recent diarrheal illness, decreased oral intake and taking more warfarin than prescribed. Inversely, the researchers found that higher intake of vitamin K (commonly found in avocados, broccoli, cabbage, green peas, lettuce and spinach) and consuming one alcoholic drink every other day to two drinks per day were associated with decreased risk. The researchers determined that 36 percent of all patients taking warfarin in the study also took acetaminophen at any given time. Thus, 30 percent of all INR values greater than 6.0 were attributable to taking seven or more tablets of acetaminophen per week. Acetaminophen is a widely used over-the-counter drug to treat mild pain and fever. It is marketed as the brand name Tylenol, but also is available in generic and other brand name products. Warfarin is an anticoagulant that is widely used to prevent thromboembolism (blockage of a blood vessel) and atrial fibrillation (irregular heart beat) - one of the most common risk factors for stroke. "Acetaminophen remains a valuable therapy for patients taking warfarin," the researchers write. "However, our findings should encourage clinicians to query patients about their use of acetaminophen and to clarify its indications. "Those patients taking warfarin who also require sustained high doses of acetaminophen need close monitoring of their INR levels."
|
