Abstract 2360: Clopidogrel Loading with 600mg Double Bolus Achieves Better Platelet Inhibition than Conventional Regimens: Results from a Randomized Study.
Background Optimal platelet inhibition is a key therapeutic goal for patients undergoing coronary intervention (PCI). Clopidogrel loading doses of 300mg and 600mg given at least 15 and 2 hours before catheterization, respectively, have been independently proposed but have not been directly compared. While 600mg has been described as the maximum absorbed dose when given as a single bolus, the effects of two 600mg boluses given 24 hours apart have not been described. Therefore, the optimal clopidogrel loading dose remains unknown. The objective of this study was to compare the degree of platelet inhibition achieved by 3 different clopidogrel loading regimens in patients undergoing elective angiography and PCI when appropriate.
Methods Patients (n=134) were randomly assigned to one of 3 regimens: Group A, clopidogrel 300 mg the day before (>15 hours) + 75mg the morning of the procedure Group B, clopidogrel 600 mg the morning of the procedure(>2 hours) Group C, clopidogrel 600 mg the day before and 600 mg the morning of the procedure (>15 and >2 hours). Blood samples were obtained at baseline and immediately before angiography. Standard platelet aggregometry was meticulously performed on each sample in a blinded core lab.
Results See TABLE⇓. There was a consistent difference favoring Group C in all aggregation parameters (p<0.001). Peak aggregation (Aggpeak ) absolute values before angiography were 42.0, 39.5, and 29.8 in groups A+B+C, respectively (5umol ADP, p>0.0001). Late aggregation (Agg6min) absolute values were 25.8, 20.6, and 10.5 (5umol ADP, p<0.0001). These results were also significant with 20umol ADP. All comparisons between group C and other groups were significant, and those between group A and B were not.
Conclusions The effects of clopidogrel 300+75 (>15hours) and 600mg (>2 hours) regimens are equivalent and the optimal clopidogrel loading dose is 600mg double bolus given the day before (>15hours) and the morning of (>2hours) an interventional procedure.