CHANCE Trial Clopidogrel Dosage
The CHANCE trial used a 300 mg loading dose of clopidogrel followed by 75 mg daily maintenance dose for patients with minor ischemic stroke or high-risk TIA. 1, 2, 3
Loading Dose Protocol
The CHANCE trial protocol specifically employed:
- Initial loading dose: 300 mg clopidogrel administered within 24 hours of symptom onset 1, 2
- Timing: As early as possible, ideally within 12-24 hours of minor stroke or high-risk TIA onset 2, 3
- Combined with aspirin loading dose of 160-325 mg 3
Maintenance Dosing
Following the loading dose, the CHANCE trial continued with:
- Clopidogrel 75 mg daily for 21 days 1, 2
- Aspirin 75-100 mg daily concurrently for the same 21-day period 3
- After 21 days: transition to single antiplatelet therapy (either aspirin or clopidogrel alone) 1, 3
Clinical Context and Evidence
The CHANCE trial specifically targeted patients with:
- Minor ischemic stroke (NIHSS ≤3) or high-risk TIA (ABCD2 score ≥4) 3
- Noncardioembolic mechanism 3
- Presenting within 24 hours of symptom onset 2, 3
This dual antiplatelet therapy regimen demonstrated significant benefit in reducing recurrent stroke risk during the critical first 21 days, with the 300 mg loading dose ensuring rapid platelet inhibition that standard 75 mg dosing would delay by approximately 5 days 3.
Important Distinctions from Other ACS Protocols
The CHANCE trial dosing differs from acute coronary syndrome protocols, which often use higher loading doses (600 mg) 4. The 300 mg loading dose was specifically validated for the stroke/TIA population and should not be confused with:
- 600 mg loading doses used in PCI patients 4
- Standard maintenance therapy without loading dose for stable cardiovascular disease 5
The 21-day duration is critical—extending dual antiplatelet therapy beyond 90 days significantly increases major hemorrhage risk (hazard ratio 2.22-2.32) without additional benefit 3.