August 26, 2026Journal of the American College of Cardiology528 citations
A Randomized Comparison of High Clopidogrel Loading Doses in Patients With Non–ST-Segment Elevation Acute Coronary Syndromes
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Key Result
Clopidogrel loading doses >300 mg provided significantly greater platelet inhibition than a 300-mg dose, including lower rates of low platelet inhibition (<10% at 6 h).
Key Points
- To compare the antiplatelet effects, pharmacodynamics, and clinical outcomes of three different clopidogrel loading doses in patients presenting with non-ST-segment elevation acute coronary syndromes.
- Randomized trial of 103 patients with non-ST-segment elevation acute coronary syndromes allocated to a 300-mg, 600-mg, or 900-mg clopidogrel loading dose in addition to standard therapy including acetylsalicylic acid.
- Blinded assessment of adenosine diphosphate-induced inhibition of platelet aggregation, platelet activation markers, vasodilator-stimulated phosphoprotein index, troponin I release, inflammatory markers, and major adverse cardiac events.
- Compared with the 300-mg dose, 600-mg and 900-mg loading doses achieved significantly faster onset, a higher maximal plateau, larger 24-hour area under the curve for inhibition of platelet aggregation, and fewer low-response rates (<10% at 6 hours).
- A significant dose-response relationship occurred for P2Y12 receptor inhibition measured by the vasodilator-stimulated phosphoprotein index, while troponin release, adverse cardiac events, and bleeding rates showed no significant differences among groups.
Study Design
Type
RCT (n=103)
Blinding
Blinded
Structured PICO
Do higher clopidogrel loading doses (600 mg or 900 mg) improve inhibition of platelet aggregation compared to a standard 300 mg loading dose in patients with non-ST-segment elevation acute coronary syndromes?
P
Population
103 patients with non-ST-segment elevation acute coronary syndromes evaluated over 24 hours.
I
Intervention
Clopidogrel 600-mg or 900-mg loading dose, given on top of standard therapy including acetylsalicylic acid
C
Comparator
Clopidogrel 300-mg loading dose, given on top of standard therapy including acetylsalicylic acid
O
Outcome
Inhibition of adenosine diphosphate-induced inhibition of platelet aggregation (IPA)surrogate
In patients with NSTE-ACS, clopidogrel loading doses of 600 mg or 900 mg provide faster and more potent platelet inhibition compared to the standard 300 mg dose without increasing short-term bleeding risk.
Limitations
- Findings require further clinical confirmation
Abstract
OBJECTIVES: We sought to compare the antiplatelet effects of three clopidogrel loading doses (LDs). BACKGROUND: Administration of a 300-mg clopidogrel LD is beneficial in situations requiring rapid platelet inhibition. Whether higher LDs can provide further benefits remains unknown. METHODS: Patients (n = 103) with non-ST-segment elevation acute coronary syndromes were randomized to receive a 300-mg, 600-mg, or 900-mg clopidogrel LD, given on top of other standard therapy (including acetylsalicylic acid). The main outcome measure was inhibition of adenosine diphosphate-induced inhibition of platelet aggregation (IPA); inhibition of platelet activation, inflammatory markers, troponin I release, and major adverse cardiac events also were evaluated; all measures were blindly evaluated. RESULTS: Compared with the 300-mg LD, greater doses were associated with significantly greater platelet inhibition, with dose-effect relationships observed for onset of action, maximal plateau, 24-h areas under the curves of IPA, and rates of low IPA (300 mg provide a faster onset of action, a higher IPA plateau, and greater reductions in platelet activation during the first 24 h. A 900-mg LD may induce a greater antiplatelet effect than 600 mg, when compared with the standard 300-mg regimen. These findings require further clinical confirmation.