Optimal pretreatment timing for high load dosing (600 mg) of clopidogrel before planned percutaneous coronary intervention for maximal antiplatelet effectiveness.
BACKGROUND
The optimal timing for 600 mg clopidogrel pre-treatment before planned PCI in patients with stable coronary artery disease has never been tested in a randomized trial.


METHODS
The time course of platelet inhibition was investigated in 105 patients pre-treated with clopidogrel ≥ 6 h before the planned procedure. Flow cytometric analysis of the vasodilator stimulated phosphoprotein (VASP) phosphorylation state was done and a Platelet Reactivity Index (PRI) was calculated prior to treatment (baseline) and at 12, 28, 36, 60, 84 and 108 h after the clopidogrel loading dose administration.


RESULTS
The maximal inhibition of platelet activation was seen at 28 h post administration (PRI mean 36 ± 23%), and 2/3 of patients had PRI value <50%. At 12 h 47% of patients had PRI value ≥ 50% (mean 45±21%). 600 mg of clopidogrel significantly suppressed platelet activation for 4 days. A correlation was between baseline PRI and its values by 28 h (r(S)=0.48, p<0.001), between 12 h-28 h the correlation was strong (r(S)=0.77, p<0.001).


CONCLUSIONS
The time curve of clopidogrel efficacy was dependent on baseline platelet reactivity. Among stable CAD patients, pre-treatment with 600 mg of clopidogrel resulted in maximal antiplatelet efficacy 1 day after drug administration.
Motovska
Zuzana
Z
Widimsky
Petr
P
Petr
Robert
R
Bilkova
Dana
D
Marinov
Iuri
I
Simek
Stanislav
S
Kala
Petr
P
D015906:Angioplasty, Balloon, Coronary; D000077144:Clopidogrel; D006801:Humans; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D013997:Time Factors
D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine