Effects of the glycoprotein IIb/IIIa antagonist Roxifiban on P-selectin expression, fibrinogen binding, and microaggregate formation in a phase I dose-finding study: no evidence for platelet activation during treatment with a glycoprotein IIb/IIIa antagonist.

The hypothesis that glycoprotein (GP) IIb/IIIa antagonists stimulate platelets is controversial. Here, we report the results of flow cytometric measurements of platelet activation markers in a phase I dose optimization study of Roxifiban, an orally active GP IIb/IIIa antagonist. Whole blood was collected at pre-dose and during the dosing interval directly into citrate fixative so that circulating levels of platelet activation could be assessed.