Xemilofiban/orbofiban: insight into drug development.

A number of studies have reported on the successful use of intravenous glycoprotein IIb/IIIa receptor antagonists in patients with unstable angina or undergoing percutaneous interventions. The promise of interrupting the aggregation of platelets in the setting of unstable plaques on a chronic basis had led to the evaluation of several oral agents for longer-term administration. The development program of two of these agents, xemilofiban and orbofiban, will be reviewed and evaluated to understand the selection process of therapeutic targets for use based upon complex pharmacokinetic and pharmacodynamic responses. A review of the pivotal phase III trial results will also be provided along with insights into the potential reasons for the lack of significant benefit shown with these agents to date.