This study will establish the optimal therapeutic strategy for patients with a coronary artery disease (CAD) and chronically treated with clopidogrel 75 mg/day requiring co-administration of an anti-platelet treatment with P2Y12 antagonist and a PPI for treatment/prevention of GI ulceration.

Inclusion Criteria :

• patient with stable Coronary Artery Disease (< 3 months) treated with clopidogrel (75mg/d)
• Between 18 and 75 years of age
• Body Mass Index between 18 and 30 kg/m2 and body weight not less than 60 kg
• No major bleeding according to ISTH definition
• Subjects who signed an informed consent document
• Subjects who signed a separate pharmacogenomic informed consent document
• Subjects registered to the French national welfare system

Exclusion Criteria:

• Personal or family history of coagulation or bleeding disorders
• Use of known inhibitors or inducers of CYP2C19 and CYP3A including grape fruit juice intake
• Known hypersensitivity to lansoprazole, its excipients, or substituted benzimidazoles,
• Known hypersensitivity to clopidogrel / prasugrel
• Anti-platelet treatment other than clopidogrel + aspirin within 7 days before inclusion
• Any formal indication to maintain PPI treatment
• PPI within 15 days before inclusion in the study
• Active pathology with 10 days before inclusion
• Prior history of stent thrombosis
• Prior history of Stroke
• Employee of the investigator or study center, with direct involvement in the proposed study or other studies under the direction of that investigator or study center, as well as family members of the employees or the investigator.