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)