NEW YORK (Reuters Health) – A study published today provides more evidence that proton pump inhibitors (PPI) interfere with clopidogrel.
Recommendations from the Society for Cardiovascular Angiography and Interventions, and the European Medicines Evaluations Agency (EMEA), already discourage concomitant use of PPIs and clopidogrel unless absolutely necessary. The findings of the current retrospective study make those recommendations “seem prudent,” its authors say in the Archives of Internal Medicine for April 26.
Furthermore, the current study shows that potential interactions between PPIs and clopidogrel are not limited to omeprazole.
Lead author Dr. Karen M. Stockl of Prescription Solutions in Irvine, California and colleagues found that patients who received clopidogrel plus a PPI after hospital discharge for acute myocardial infarction (MI) or coronary stent placement were significantly more likely to be readmitted for a heart problem during the next 12 months than those who received clopidogrel alone.
Using electronic pharmacy and medical claims data, Dr. Stockl and colleagues identified 1033 patients who filled prescriptions for clopidogrel and a PPI after hospital discharge for those conditions and 1033 similar patients who filled only a prescription for clopidogrel.
“This study differs from previously conducted studies because we used propensity scoring to match patients according to their baseline cardiovascular risk factors in an effort to obtain more comparable patients across treatment groups,” the researchers said.
Most patients (659; 63.8%) were taking pantoprazole, 159 (15.4%) were taking rabeprazole sodium, 86 (8.3%) were taking omeprazole, 83 (8.0%) were on lansoprazole, and 46 (4.5%) were using esomeprazole magnesium.
In the clopidogrel plus PPI group, rehospitalization for MI occurred at a rate of 9.7 events per 100 person-years compared with a rate of 4.1 events per 100 person-years in the clopidogrel-only group. The adjusted hazard ratio with dual therapy was 1.93 (p = 0.03).
Readmission due to MI or coronary stent procedure occurred at a rate of 27.6 per 100 person-years with dual therapy compared to 14.3 with clopidogrel alone, yielding an adjusted hazard ratio of 1.64 (p = 0.005).
In a subanalysis, the researchers compared the 659 patients receiving pantoprazole with matched subjects receiving clopidogrel alone. Once again, they saw a higher risk of rehospitalization for MI or coronary stent placement with dual therapy than with clopidogrel alone. (adjusted hazard ratio, 1.91; p = 0.008).
Dr. Stockl and her colleagues say their study differs from earlier reports because it included a more representative population (including women and patients older than 65) and because it matched PPI users with patients with similar demographic and cardiovascular risk histories not taking a PPI.
Until more is known, “individual patient characteristics will
