Painkiller may limit aspirin heart benefit

Wednesday December 16th, 2009

A common painkiller stops low-dose aspirin from cutting the risk heart attack and stroke, researchers have reported.

Celebrex is a non-steroidal anti-inflammatory drug, in a class of drugs known as COX-2 inhibitors. It is widely used as a painkiller for arthritis. A large number of patients also take low-dose aspirin daily to avoid blood clotting and reduce their risk of heart disease.

But Celebrex stops aspirin from doing its job effectively, say Dr William Smith of the University of Michigan, USA, and colleagues. They discovered that celecoxib binds to an enzyme that promotes clotting called COX-1, and slows aspirin's COX-1-blocking action.

Animals given Celebrex plus low-dose aspirin showed more clumping of platelets than animals given low-dose aspirin only. Full results are published in the Proceedings of the National Academy of Sciences.

Dr Smith said: "There are many people who take low-dose aspirin, perhaps as many as half of men over 50. If they are also prescribed Celebrex for arthritis or other pain, our results suggest that the Celebrex will probably interfere with the aspirin's action.

"The greatest risk is having people take Celebrex who are taking aspirin for cardiovascular problems that are known to be mitigated by aspirin, including patients with unstable angina or those at risk for a second heart attack."

Aspirin is often prescribed at a low dose of approximately 81 mg per day to protect against heart disease. When Celebrex is combined with aspirin at higher doses (approximately 324 mg), there is no ill effect on blood clotting, Dr Smith says, so it may still be possible to gain the benefits of both drugs.

Rimon, G. et al. Coxibs interfere with the action of aspirin by binding tightly to one monomer of cyclooxygenase-1. Proceedings of the National Academy of Sciences, published online December 1, 2009.

Tags: Heart Health | North America | Pain Relief | Pharmaceuticals

Printer friendly page