Morphine Decreases Clopidogrel€Concentrations and Effects

Results M orphine injection delayed clopidogrel absorption (p 1⁄4 0.025) and reduced the area under the curve levels of its active metabolite by 34% (p 1⁄4 0.001). Morphine delayed the maximal inhibition of platelet aggregation on average by 2 h (n 1⁄4 24; p < 0.001). Residual platelet aggregation was higher 1 to 4 h after morphine injection (n 1⁄4 24; p < 0.005). Furthermore, morphine delayed the inhibition of platelet plug formation under high shear rates (P2Y-Innovance; n 1⁄4 21; p < 0.004) and abolished the 3-fold prolongation in collagen adenosine diphosphateinduced closure times seen in extensive and rapid metabolizers (n 1⁄4 16; p 1⁄4 0.001).