We saw many patients who came in with ACS, have been in Omeprazole for their stomach problem.

ACS protocol needs to start Aspirin and clopidogrel. Omeprazole significantly decreased clopidogrel inhibitory effect on platelet according to the evidence based medicine.

So we replace Omeprazole with Ranitidine.

Here is the related article on HeartWire.

Munich, Germany - A new study using platelet-aggregometry testing to assess the effects of different proton-pump inhibitors (PPIs) on platelet response to clopidogrel suggests that omeprazole might be alone in adversely interacting with the widely used antiplatelet therapy [1]. The study, published in the April 2009 issue of Thrombosis and Haemostasis, hints that other PPIs tested—pantoprazole and esomeprazole—might be a safer bet for minimizing gastrointestinal side effects and bleeding in patients requiring long-term clopidogrel treatment.........See more here
http://www.theheart.org/article/960023.do