For most patients with prior cardiovascular events, preventing future secondary cardiovascular events requires life-long persistence with antiplatelet therapy. PA tablets (P: proton pump inhibitors; A: aspirin) are investigational compounds that were developed to provide the cardioprotective benefits of aspirin with the upper gastrointestinal protection of a proton pump inhibitor (e.g., omeprazole). The tablets are film-coated, coordinated-release tablets for oral administration that contain 40 mg immediate-release omeprazole and either 81 or 325 mg delayed-release aspirin. The goals of the clinical development program were to demonstrate the following: improved gastrointestinal safety of PA relative to enteric-coated aspirin alone; bioequivalence and comparative bioavailability between the PA compounds and currently marketed enteric-coated aspirin; and long-term safety. Two clinical pharmacology studies were also conducted to study the potential for interaction between PA32540 and clopidogrel.