Effect of caffeine on platelet inhibition by clopidogrel in healthy subjects and patients with coronary artery disease

Eli I. Lev, Mehmet E. Arikan, Muthiah Vaduganathan, Carlos L. Alviar, Armando Tellez, Nilesh Mathuria, Angela Builes, Juan F. Granada, Ian del Conde, Neal Kleiman

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Background: Clopidogrel inhibits the platelet P2Y12 receptor, leading to increased intracellular cyclic AMP (cAMP) levels. Caffeine also causes a rise in platelet cAMP. We aimed to test the effect of acute caffeine administration on platelet inhibition by clopidogrel, in healthy volunteers and patients with coronary artery disease. Methods: Cohort 1: 12 healthy subjects were enrolled in a 2-week crossover study. Blood samples were drawn at baseline, 2, 4, and 24 hours after 300 mg clopidogrel intake. At the first week, 6 subjects received caffeine (300 mg pill, equivalent to a medium sized coffee drink) 30 minutes after clopidogrel. At week 2, the other 6 subjects received caffeine. One month later the effect of caffeine alone was tested. Platelet function was evaluated by aggregation in response to 5, 10, and 20 μmol/L adenosine diphosphate, 1 μg/mL collagen, and flow cytometric determination of P-selectin expression, PAC-1 binding, and vasodilator-stimulated phosphoprotein phosphorylation. Cohort 2: 40 patients with coronary artery disease receiving aspirin and clopidogrel (75 mg daily) for ≥1 week were tested at baseline and 2.5 hours after caffeine (300 mg). Results: In cohort 1 (crossover study), caffeine was associated with lower adenosine diphosphate-induced aggregation at 4 hours, lower activation markers at 2 hours, and lower vasodilator-stimulated phosphoprotein phosphorylation at 4 hours after clopidogrel. Caffeine alone had no effect on the assessed platelet surface biomarkers. In cohort 2, caffeine administration was associated with lower platelet activation markers (P-selectin, PAC-1 binding), without significant effect on aggregation. Conclusions: Acute caffeine administration after clopidogrel loading appears to be associated with enhanced platelet inhibition 2 to 4 hours after clopidogrel intake. The mechanism probably involves synergistic increase in cAMP levels.

Original languageEnglish (US)
Pages (from-to)694.e1-694.e7
JournalAmerican Heart Journal
Issue number4
StatePublished - Oct 2007

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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