The study also suggested that combining the drugs did not increase the risk of serious heart problems. Clopidogrel (sold as Plavix, Clopilet, and Ceruvin) is usually prescribed for heart patients to reduce the risk of a heart attack or stroke and can also cause bleeding stomach ulcers. Proton-pump inhibitors, which include pantoprazole (Protonix), omeprazole (Prilosec), lansoprazole (Prevacid), esomeprazole (Nexium) and rabeprazole (Aciphex), are used to prevent or treat ulcers, acid reflux disease and other stomach acid-related problems.

Although proton-pump inhibitors are commonly prescribed with clopidogrel to reduce the risk of upper digestive tract bleeding, clinicians worry that this practice may decrease the antiplatelet drug’s ability to prevent blood clots. Until now, there has been limited research on the impact of proton-pump inhibitors on either the effectiveness of clopidogrel or on the ability of the proton-pump inhibitors to reduce digestive tract bleeding and which populations of patients may benefit the most from taking the drugs in combination.

“We need to make sure that the medicines we give patients help and don’t harm” said AHRQ Director Carolyn M. Clancy, M.D. “This evidence on benefits and risks helps inform the combined use of these two drugs.”

The study, published in the March 16 issue of the Annals of Internal Medicine, was based on data from nearly 21,000 patients in the Tennessee Medicaid program between 1999 and 2005. Researchers divided those patients into two groups – those who were prescribed clopidogrel by itself and those who took clopidogrel in combination with a proton-pump inhibitor. The researchers from Vanderbilt University Medical Center in Nashville then determined how many patients in each group had been hospitalized for gastrodoudenal ulcers – raw tissue in the upper part of the small intestine, or duodendum, where it connects to the stomach. The Vanderbilt research team is one of 14 AHRQ-supported Centers for Education & Research on Therapeutics (CERTs).

The researchers found that concurrent use of a proton-pump inhibitor and clopidogrel did not increase patients’ risk of heart attack, sudden cardiac death, stroke or other cardiovascular problems. The same was true for patients who had a procedure called percutaneous coronary intervention, also known as angioplasty with stents.

However, the researchers noted that even though they did not find an elevated cardiovascular risk, they cannot rule it out. They noted data from additional studies, including randomized clinical trials, will clarify how combining clopidogrel and proton-pump inhibitors affects heart and vascular health.