Batifiban,a synthetic cyclic peptide,is a potent platelet glycoprotein GPⅡb/Ⅲa an-tagonist which may be useful in the treatment and prevention of acute coronary syndromes. The pharmacokinetics and pharmacodymanic (inhibition of platelet aggregation) effects,and tolerability of batifiban were investigated in healthy subjects following single bolus injection with doses of 55,110,or 220 μg/kg,or multiple doses of an bolus followed intravenous infusion for 24 h (180 μg/kg of batifiban and areas under the curve were found to be proportional to doses. Batifiban was rapidly eliminated with a half-life of approximately 2.5 h. Significant differences were noted for plasma lev-els of batifiban and areas under the curve between males and females. No significant differences in the terminal half-life were found between males and females. Batifiban reversibly inhibited ex vivo platelet aggregation in a dose- and concentration-dependent manner,consistent with its mechanism as a GP Ⅱb/Ⅲa antagonist. Single and multiple intravenous doses of batifiban were found to be safe and well tolerated in healthy subjects. These results support a bolus injection plus intravenous infusion regimen of batifiban for the treatment and prevention of acute coronary syndromes.