The investigators sought to evaluate the influence of pantoprazole, indicated as less effective than other proton pump inhibitors, on the antiplatelet effect of clopidogrel, with stratification of the population according to the presence of cytochrome (CYP) 2C19 polymorphism.

Participants being treated with a maintenance dose of 75 mg clopidogrel and 100 mg aspirin daily after previous PCI with coronary stenting were included in the study. Participants were randomly assigned to either the pantoprazole 40 mg once-daily group or the ranitidine 150 mg twice-daily group using a computer-generated randomized table. An independent investigator generated the random allocation sequence. Blood samples were collected at 9:00 on day prior to treatment (day 0) and on day 9. Measuring impedance was performed by one independent investigator in a blinded manner.

Inclusion Criteria:

• Patients being treated with a maintenance dose of 75 mg clopidogrel and 100 mg aspirin daily after previous PCI with coronary stenting were included in the study. All patients received standardized therapy with a loading dose of 600 mg of clopidogrel hydrogen sulfate and 400 mg aspirin.

All participants had a normal platelet count (150,000-450,000/mL).

Exclusion Criteria:

• Patients with severe liver disorders, current gastrointestinal disorders, a current infection, congestive heart failure, or a known bleeding disorder as well as patients on bivalirudin or glycoprotein IIb/III antagonists within the last 7 days were excluded from the study.