High Platelet Count in Platelet-Rich Plasma Reduces Measured Platelet Inhibition by Abciximab but not Tirofiban nor Eptifibatide Glycoprotein IIb/IIIa Receptor Antagonists

We evaluated the differential effect of platelet count in platelet-rich plasma (PRP) on the level of ex vivo inhibition of platelet aggregation provided by abciximab, eptifibatide, and tirofiban as part of a randomized, comparative trial of these agents on platelet function in patients with unstable angina pectoris undergoing percutaneous coronary intervention. Platelet count <350 K/µL in PRP reduced measured platelet inhibition by abciximab, but not eptifibatide nor tirofiban. This observation suggests the need for standardized, uniform platelet counts in PRP during future comparisons of the degree of platelet inhibition by these agents.