Clopidogrel Dosing

The usual dose for clopidogrel is 75mg once a day.

Start 5 days prior to the actual procedure because there is a 3–7 days latency period to full therapeutic effect.

LD: 300 mg PO, if there was no time to achieve therapeutic e ect over a course of days. A therapeutic effect can usually be achieved within 2 to 3 hours of LD.

Dosing Modifications

Renal impairment: Dose adjustment not necessary Hepatic impairment: Use caution; experience limited Dosing Considerations

CYP2C19 poor metabolizers associated with diminished antiplatelet response to clopidogrel; although higher-dose regimen (600 mg loading dose followed by 150 mg once daily) in poor metabolizers increases antiplatelet response, no appropriate dosing regimen for poor metabolizers has been established in clinical outcome trials Not recommended for pediatric use

Reduced Clopidogrel high on treatment platelet reactivity (CR) can lead to Clopidogrel underactivity (CU) causing acute thrombosis. However, the prevalence of CU among patients with acute symptomatic carotid artery disease remains unknown. Therefore, Honig et al. aimed to find the prevalence and identify the predictors for CU among patients with acutely symptomatic carotid stenosis.

Over the span of 14 months, CR was measured at the time of endovascular procedure in all patients undergoing angiography and stenting because of acute symptomatic carotid stenosis. Only patients treated per institutional protocol with a combination of Clopidogrel and Aspirin were included. CR was measured with P2Y12 reaction units (PRU) and CU was defined as PRU > 208. Patients with CU were compared to those without CU.

Thirty-five patients were included (mean age 71.3 ± 10, 76% men) and twelve (34.3%, mean age 71.8 ± 8.4, 58% men) had CU at the time of endovascular intervention. On univariate analysis more severe carotid stenosis was seen in CU patients (92.6 ± 6.5% vs 81.6 ± 13.6%, p = 0.013) and percent stenosis was independently associated with CU on multivariate analysis (p = 0.023).

Clopidogrel underactivity (CU) is present in 1 of every 3 patients with acutely symptomatic carotid artery disease. The current results suggest that platelet reactivity testing should become part of routine care in patients with acutely symptomatic carotid disease ¹⁾.