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 <50,000/µL)
4. End-stage renal disease requiring dialysis, or unstable renal function precluding safe anticoagulant dose adjustment (eGFR <15 mL/min/1.73m²)
5. Known hypersensitivity to potassium-competitive acid blockers (P-CABs) or to the investigational product
6. History of major gastrointestinal surgery resulting in malabsorption, bowel obstruction, or inability to take oral medication
7. History of osteoporotic fracture or fragility fracture
8. Diagnosis of a condition requiring long-term, high-dose systemic corticosteroid therapy
9. Diagnosis of a condition requiring long-term concomitant use of non-steroidal anti-inflammatory drugs (NSAIDs)
10. Pregnant or breastfeeding women
11. Life expectancy of less than 6 months due to pre-existing comorbid conditions
12. Current participation in another interventional clinical trial that could affect the results of this study
13. Any condition that, in the investigator's judgment, precludes participation
14. Participant or partner of childbearing/reproductive potential who does not agree to use a medically acceptable method of contraception, or to abstain from sexual activity with risk of pregnancy, during the study period
15. Currently receiving, or having received within 5 half-lives prior to randomization, a prohibited concomitant medication expected to interact with the investigational product (products containing atazanavir, nelfinavir, or rilpivirine)
16. History of peptic ulcer complications, including bleeding, perforation, or stricture, regardless of timing
17. Active bleeding at the time of enrollment, history of a coagulation disorder, or hemodynamic instability at the time of enrollment
18. Known hereditary conditions such as galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption