Mexidol® Safety and Efficacy in Treatment of Hyperacute and Acute Ischemic Stroke

Inclusion Criteria for Patients: 1. Signed and dated Informed Consent Form (ICF) by the patient or their legal representative (in case of physical inability to sign), and/or a Decision of the Medical Board. 2. Men and women aged 18 to 90 years (inclusive) at the time of signing the ICF or Decision of the Medical Board. 3. First-ever hemispheric ischemic stroke (ICD-10 codes: I63.0-I63.9), confirmed by neuroimaging (CT or MRI). 4. Presence of occlusion in the internal carotid artery (ICA) system at any level, including the middle cerebral artery (MCA) and anterior cerebral artery (ACA) (anterior circulation) and/or presence of neuroimaging signs, characteristic of acute cerebral ischemia (based on CT perfusion and/or MRI data in accordance with current Clinical Guidelines). Note: Presence of internal carotid artery (ICA) occlusion is not a mandatory criterion; neuroimaging signs of acute cerebral ischemia (CT perfusion/MRI) are sufficient for inclusion. 5. Time from the onset of acute ischemic stroke symptoms or the time the patient was last known to be well (last known well, LKW) to randomization is no more than 36 hours. 6. No significant pre-stroke disability (the patient is able to carry out all daily activities and duties without assistance, a score of 0-1 on the modified Rankin Scale (mRS)). 7. Total National Institutes of Health Stroke Scale (NIHSS) score of 6 to 20 (inclusive) at screening, provided that the score for item 5a/b (Motor Arm: Left/Right) is at least 2 points on the paretic side and/or item 6a/b (Motor Leg: Left/Right) is at least 2 points on the paretic side. 8. 8\. Agreement to use highly effective methods of contraception throughout the study and for 3 weeks after study completion. Eligible participants include: women of childbearing potential, who must have a negative pregnancy test and agree to use the following contraceptive methods: a barrier method (condom or occlusive cap \[diaphragm or cervical/vault cap\]) or a double-barrier method (condom or occlusive cap \[diaphragm or cervical/vault cap\] plus spermicide \[foam/gel/film/cream/suppository\]); women of non-childbearing potential with documented history of hysterectomy, tubal ligation, infertility, or postmenopausal status (at least 1 year of amenorrhea); fertile men who must agree to use barrier contraception; men with documented infertility or prior vasectomy. Inclusion Criteria for Healthy Volunteers: 1. White male and female participants aged 18 to 45 years inclusive at the time of signing the Informed Consent Form (ICF). 2. Verified "healthy" status based on standard clinical, laboratory, and instrumental examination methods. 3. Ability to provide written informed consent prior to any screening procedures, and the ability, in the investigator's opinion, to comply with all study protocol requirements. 4. Hemodynamic parameters: systolic blood pressure (SBP) within 100-130 mmHg, diastolic blood pressure (DBP) within 60-90 mmHg, heart rate (HR) 60-90 bpm, and respiratory rate (RR) 16-20 breaths per minute. 5. Body Mass Index (BMI) from 18.5 to 30 kg/m² inclusive. 6. Willingness to abstain from alcohol throughout the entire study period. 7. Agreement to use highly effective methods of contraception throughout the entire study. Eligible participants include: women of childbearing potential, who must have a negative pregnancy test and agree to use the following contraceptive methods: a barrier method (condom or occlusive cap \[diaphragm or cervical/vault cap\]) or a double-barrier method (condom or occlusive cap \[diaphragm or cervical/vault cap\] plus spermicide \[foam/gel/film/cream/suppository\]); women of non-childbearing potential with documented history of hysterectomy, tubal ligation, infertility, or postmenopausal status (at least 1 year of amenorrhea); fertile men who must agree to use barrier contraception; men with documented infertility or prior vasectomy. Exclusion Criteria for Patients: 1. Hypersensitivity to ethylmethylhydroxypyridine succinate or any other components of the investigational product. 2. Galactose intolerance, lactase deficiency, or glucose-galactose malabsorption. 3. Inability to take oral medications. 4. Contraindications or inability to undergo CT/MRI procedures (including, but not limited to: permanent cardiac pacemakers/neurostimulators; inner ear prosthesis, ferromagnetic or electronic middle ear implants, hemostatic clips, cardiac valve prostheses, or any other metal-containing structures; ferromagnetic fragments; insulin pumps; severe claustrophobia). 5. Inability to undergo contrast-enhanced imaging for any reason. 6. Patients who have received or are scheduled to receive thrombolytic therapy or thrombectomy for the current episode of ischemic stroke. 7. Recurrent ischemic stroke. 8. Direct signs of irreversible total occlusion of the internal carotid artery (ICA) system at the relevant level within the current episode of ischemic stroke (based on CT/MRI data). 9. Absence of neuroimaging signs of acute ischemic brain injury. 10. Presence of any of the following neuroimaging (CT/MRI) findings: * Intracranial hemorrhage; * Hemorrhagic transformation of the cerebral infarction; * Subarachnoid hemorrhage; * Brain tumor; * Arteriovenous malformation (AVM); * Brain abscess; * Cerebral aneurysm; * Edema of the infarct zone leading to brain structure displacement (malignant cerebral infarction). 11. Lesion in the vertebrobasilar system. 12. Any suspicion of subarachnoid hemorrhage (SAH) in the medical history or at the time of screening. 13. History of hemorrhagic stroke or stroke of unspecified nature. 14. Any known history of conditions associated with a bleeding tendency. 15. Deep vein thrombosis (DVT) or pulmonary embolism (PE), or detection of a floating thrombus. 16. Traumatic brain injury (TBI) within 6 months prior to screening. 17. History of brain or spinal cord surgery within 5 years prior to study enrollment. 18. Need for surg