The primary objective of this study is to evaluate the efficacy of PG2 Injection 500 mg versus placebo, administered intravenously within 3-6 hrs of stroke onset to patients with an acute ischemic stroke, as determined by Modified Rankin Scale (mRS) score at Day 90.

The secondary objectives are as follows:

• To evaluate the efficacy of PG2 Injection 500 mg versus placebo as determined by Barthel Index (BI) score at Day 90.
• To evaluate the efficacy of PG2 Injection 500 mg in reducing the risk of recurrent stroke, cardiovascular events and death of all causes.
• To evaluate the safety of PG2 Injection 500 mg treatment

Randomized, double-blind, placebo-controlled multi-center study of intravenous (IV) PG2 Injection 500 mg starting within 3-6 hrs of the onset of acute ischemic stroke

Inclusion Criteria:

1. Patients presenting with acute ischaemic stroke
2. Patient, or a family member with legally authorized responsibility, has given informed consent
3. Age ≥20 years
4. Infusion of study medication can be started within 3-6 hrs of stroke onset.
5. NIHSS score of ≥ 7 - 24

Exclusion Criteria:

1. Intracranial haemorrhage (ICH) identified by CT or MRI
2. Rapidly improving symptoms, particularly if in the judgment of the managing clinician that the improvement is likely to result in the patient having an NIHSS score of < 6 at randomization
3. Pre-stroke mRS score of ≥ 2 (indicating previous disability)
4. Known allergy to Astragalus membranaceus or its mayor derivatives (polysaccharides)
5. Patients who are eligible for tPA treatment and has been treated with tPA.
6. Participation in any investigational study in the previous 30 days
7. Any terminal illness such that patient would not be expected to survive more than 1 year
8. Any condition that could impose hazards to the patient if study therapy is initiated or affect the participation of the patient in the study (this applies to patients with severe microangiopathy such as haemolytic uremic syndrome or thrombotic thrombocytopenic purpura). The judgment is left to the discretion of the Investigator
9. Pregnant women (clinically evident)
10. Previous stroke within last three months
11. Past history or clinical presentation of ICH, arterio-venous (AV) malformation, aneurysm, or cerebral neoplasm.
12. Current use of oral anticoagulants with prolonged prothrombin time (INR > 1.6)
13. Use of heparin, except for low dose subcutaneous heparin, in the previous 48 hrs and a prolonged activated partial thromboplastin time exceeding the upper limit of the local laboratory normal range
14. Clinically significant hypoglycaemia (blood sugar < 50mg/dl)
15. Uncontrolled hypertension defined by a blood pressure > 185 mmHg systolic or >110 mmHg diastolic on at least 2 separate occasions at least 10 minutes apart, or requiring aggressive treatment to reduce the blood pressure to within these limits. The definition of "aggressive treatment" is left to the discretion of the responsible Investigator
16. Major surgery within the preceding 14 days which poses risk in the opinion of the Investigator