Probucol for Symptomatic Intracranial and Extracranial Artery Stenosis

Inclusion Criteria: 1.40 years or older than 40 years; 2.Ischemic stroke or transient ischemic attack (TIA); 3.Within 7 days from onset to randomization; 4.Main intracranial or extracranial arteries supplying the ischemic event region are narrowed by more than 50%; 5.Informed consent signed. Exclusion Criteria: 1. Presumed cardiac source of embolus, such as atrial fibrillation, prosthetic cardiac valve, endocarditis or patent foramen ovale; 2. Stroke/TIA due to arterial dissection, angioplasty, or vascular surgery; 3. Usage of probucol within 30 days before randomization; 4. Known allergy or sensitivity or intolerance to probucol; 5. Myocardial disease within the past 30 days, including myocardial infarction, myocarditis; 6. With ventricular tachycardia, bradycardia, tip-twist ventricular tachycardia； 7. With Q-Tc interval prolongation, or currently using drugs that may cause Q-Tc interval prolongation (male Q-Tc\>450ms, female Q-Tc\>470ms); 8. Cardiac syncope or unexplained syncope; 9. Impaired hepatic (ALT or AST \> twice the upper limit of normal range) or kidney (creatinine exceeding 1.5 times of the upper limit of normal range or eGFR less than 50 ml/min) function at randomization; 10. Anemia (haemoglobin \<10g/dL), thrombocytopenia (platelet count \<100×109/L) or leucopenia (white blood cell \<3×109/L) at randomization; 11. Planned surgery or interventional treatment requiring cessation of the study drug during the study; 12. Participating in another clinical trial with an investigational drug or device concurrently or during the last 30 days; 13. Pregnant or lactating women; Pregnant, currently trying to become pregnant, or of child-bearing potential and not using birth control; 14. Severe non-cardiovascular comorbidity with a life expectancy of less than 1 years; 15. Serious drug or alcohol abuse in the past 1 year； 16. Inability to understand and/or follow research procedures due to mental, cognitive, or emotional disorders, or to be an unsuitable candidate for the study for any other considered by the investigator.