Zastaprazan for the prEvention of Upper GI Bleeding in Ischemic Stroke

The goal of this clinical trial is to learn if zastaprazan can help prevent upper gastrointestinal bleeding in adults who have recently had a transient ischemic attack (TIA) or ischemic stroke and are taking antiplatelet or anticoagulant medications. The main question it aims to answer is: \- Does zastaprazan reduce the risk of upper gastrointestinal bleeding compared to placebo in these patients? Researchers will compare zastaprazan to a placebo (a look-alike tablet that contains no drug) to see if zastaprazan works to prevent upper gastrointestinal bleeding. Participants will: * Take zastaprazan (20 mg) or a placebo once daily for the duration of the study, in addition to their prescribed antiplatelet or anticoagulant medication * Visit the study site regularly for safety monitoring, including vital signs, physical exams, and laboratory tests * Be monitored for any signs of gastrointestinal bleeding or other adverse events for up to approximately 3 years (including screening, treatment, and follow-up periods)

Inclusion Criteria: 1. Adults aged 19 years or older 2. Onset of transient ischemic attack (TIA) or ischemic stroke within 180 days prior to randomization 3. Currently initiating or receiving, at the time of randomization, one of the following treatments, with an expected treatment duration of at least 3 weeks: A. Dual antiplatelet therapy (DAPT) - aspirin in combination with one of the following: clopidogrel, ticagrelor, prasugrel, or cilostazol B. Oral anticoagulant therapy - a NOAC (apixaban, rivaroxaban, dabigatran, or edoxaban) or warfarin 4. Provision of written informed consent by the participant (or legally authorized representative) Exclusion Criteria: 1. Clinically significant peptic ulcer or gastrointestinal bleeding within 1 year prior to enrollment 2. Moderate to severe hepatic impairment (e.g., diagnosis of cirrhosis or confirmed esophageal/gastric varices) 3. Severe thrombocytopenia (platelet count \