Heart attack and stroke protection of aspirin blocked by Ibuprofen and similar medicines (NSAIDs)
Kathy Orrico, Pharm.D. BCPS*
Henry I. Bussey, Pharm.D., FCCP, FAHA
Recently the FDA released information about the use of ibuprofen blocking the heart attack protective effect of low-dose (81mg) immediate release aspirin, when the two drugs are taken at the same time. It is logical that the problem probably occurs in patients who are taking aspirin to prevent strokes, as well. Aspirin should be taken at least 30 minutes prior to a dose of ibuprofen and potentially any non-steroidal anti-inflammatory drug (NSAID). Alternatively, patients may wait at least 8 hours after taking a dose of ibuprofen before taking their daily aspirin dose in order to avoid losing the beneficial effects of aspirin, which works by reducing the ability of blood cells called platelets to make a blood clot.
This is the first of what is likely to be a series of recommendations based on the FDA's review of published and unpublished studies that demonstrate that NSAIDs block the effect of aspirin on platelets. Aspirin produces its effect on platelets by permanently binding to a platelet enzyme called cyclooxygenase. Because the effect is permanent, the platelets that are exposed to aspirin do not function normally for entire 7 day life-span of the platelet. New platelets have to be produced before the body has normally functioning platelets.
Ibuprofen and other NSAIDs also bind to the enzyme cyclooxygenase, but only for a short period of time. This temporary binding, however, can block aspirin from binding to the enzyme. This blocking of the effect of aspirin (and its protective effect against heart attack and stroke) can be avoided by allowing aspirin to arrive and bind to the enzyme before the NSAID arrives or after the NSAID has left.
Since the studies only examined the immediate release, low-dose aspirin, it is unclear how enteric coating aspirin (that may dissolve more slowly) or higher doses of aspirin would be affected in a similar way. Significant aspirin blood levels usually do not appear until 6 hours or more after single dose administration of enteric coated aspirin.
To read more about the FDA's statement, go to: http://www.fda.gov/medwatch/safety/2006/safety06.htm#aspirin.
* Guest Editor: Kathy Orrico, Pharm.D. BCPS
Assistant Professor of Pharmacy
University of California San Francisco
Clinical Pharmacy Coordinator
Palo Alto Medical Foundation