M. Karatepe, A. Mani, D. Soffer, G. Taviloglu, E. Kreps, M. Collins, S. Iyer, G. Roubin, J. Moses, N. Coplan, I. Moussa Lenox Hill Heart and Vascular Institute, New York, New York, USA
Background
The optimal loading dose of clopidogrel prior to coronary stenting is still undetermined. We compared the degree of platelet inhibition (PI) following administration of 150 mg, 300 mg, and 450 mg of clopidogrel in patients referred for coronary stenting.
Methods
Clopidogrel was administered as a loading dose of 150 mg, 300 mg, and 450 mg in 148, 25, and 65 patients, respectively. Blood was collected at various time intervals after loading. Inhibition of ADP-mediated platelet aggregation was measured with the Ichor CBC analyzer (Array Medical, Somerville, New Jersey) utilizing 20 µmol of ADP. Patients were divided according to the loading dose received (150 mg, 300 mg, 450 mg) and according to time interval from the drug loading (<3 hours, 3-9 hours, 9-24 hours). Repeated measures ANOVA with Bonferroni multiple comparison tests was used to determine whether there was any difference among groups.
Results
Patients treated with 150 mg of clopidogrel had significantly lower PI than those receiving 300-mg and 450-mg doses (mean PI ± SE: 8 ± 1%, 24 ± 3%, and 26 ± 2%, respectively, p <0.0001). Patients treated with 450 mg clopidogrel had significantly higher levels of PI in the time window 3-9 hours after loading, with no difference before 3 hours and after 9 hours when comparing the 300-mg dose (see Table).
Conclusion
These data show that when clopidogrel is administered as a loading dose prior to coronary intervention, the 450-mg dose should be accepted as the most effective loading dose. The clinical impact of these findings, if validated by randomized trials, should be considered prior to coronary intervention.
Source: Am J Cardiol 2000; 86(supp1 8A): 15i
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