Known brand names include Plavix.
An oral antiplatelet drug that keeps platelets from clumping. It lowers the risk of heart attack and stroke after acute coronary syndrome, a recent heart attack or stroke, or with peripheral artery disease.
Labeled use. NSTEMI and STEMI with aspirin, and secondary prevention after a recent MI.
Labeled use. Reduces MI and stroke in established peripheral arterial disease.
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Clopidogrel is the usual P2Y12 inhibitor for dual antiplatelet therapy in stable coronary disease, after elective stenting, and when bleeding risk is high or ticagrelor or prasugrel are unsuitable. It is the antiplatelet alternative for patients intolerant of aspirin and is used for stroke and peripheral artery disease. In ACS, ticagrelor or prasugrel give stronger, more consistent platelet inhibition. Avoid relying on it in known CYP2C19 poor metabolizers.
A prodrug. Liver CYP enzymes, mainly CYP2C19, convert it to an active metabolite that binds the platelet P2Y12 ADP receptor irreversibly. This blocks ADP-driven activation of the GP IIb/IIIa complex, so platelets cannot aggregate for the rest of their lifespan (about 7 to 10 days). Steady-state inhibition is reached between day 3 and day 7 without a loading dose.
The label does not describe a narrow therapeutic index or direct dosing by measured blood levels of the drug.
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Doses come from the FDA label. Study tool, not for clinical decisions.
No dose change is labeled. Experience in moderate and severe renal impairment is limited, and platelet inhibition was lower in these patients.
Reduced effect in CYP2C19 poor metabolizers. Clopidogrel works only after CYP2C19 converts it to its active form. Patients with two loss-of-function CYP2C19 alleles make less active metabolite and get less platelet inhibition. Genetic tests can identify them; consider another P2Y12 inhibitor for these patients.
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Case reports and postmarketing data have not shown a risk of major birth defects or miscarriage. Do not withhold it for MI or stroke. It raises maternal bleeding risk at delivery: stop 5 to 7 days before labor, delivery, or neuraxial blockade when possible, and avoid neuraxial blockade while taking it.
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No human milk data. It is present in rat milk, and no infant harm was seen in a small number of postmarketing cases. Weigh breastfeeding benefits against maternal need.
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Safety and effectiveness in children have not been established. A trial in infants with shunted cyanotic congenital heart disease showed no clinical benefit.
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No dose adjustment is needed in older adults. Bleeding risk with aspirin plus clopidogrel was reported by age group in trials, so monitor closely for bleeding.
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