Sustained platelet glycoprotein IIb/IIIa blockade with oral xemilofiban in 170 patients after coronary stent deployment

Background: Inhibition of platelet aggregation with parenteral glycoprotein (GP) IIb/IIIa receptor blockers can reduce the ischemic complications of angioplasty. Sustained efficacy and safety of protracted GP IIb/IIIa blockade with an orally administered agent have not previously been determined. This study is the first randomized, dose-ranging, single-blind, placebo-controlled trial of xemilofiban, an oral platelet GP IIb/IIIa receptor antagonist, administered to patients after intracoronary stent deployment. The pharmacodynamic efficacy of xemilofiban-induced platelet inhibition and clinical safety of this agent was evaluated during chronic therapy. Methods and Results: After elective intracoronary stent deployment, patients were randomized to receive placebo (250 mg ticlopidine PO BID) or xemilofiban in doses of 5, 10, 15, or 20 mg PO BID. All patients received 325 mg aspirin PO QD. Inhibition of ex vivo platelet aggregation in response to 20 μmol/L ADP and 4 μg/mL collagen was measured over time after the initial dose of study drug and at 1 and 2 weeks of chronic therapy. Study drug was discontinued after 2 weeks, and all patients were followed clinically for ≤30 days. Oral xemilofiban resulted in a dose-dependent inhibition of platelet aggregation in response to both agonists that was sustained through 2 weeks of chronic therapy. Doses of xemilofiban required to achieve ≤50% inhibition of platelet aggregation were ≤10 mg, and the duration of inhibition was 8 to 10 hours. No significant hemorrhagic episodes or blood transfusions were observed in this trial. Conclusions: Oral xemilofiban in doses of ≤10 mg produced ≤50% inhibition of platelet aggregation in response to ADP and collagen for 8 to 10 hours after dosing. Platelet inhibition was sustained through 2 weeks of chronic therapy. The optimal duration of oral GP IIb/IIIa blockade to effectively suppress recurrent ischemic events after coronary intervention remains to be determined.