title: Pharmacodynamics and pharmacokinetics of eptifibatide in patients with acute coronary syndromes: prospective analysis from PURSUIT.
abstract: BACKGROUND
  Platelet deposition and aggregation are central to the pathogenesis of ischemic complications of acute coronary syndromes (ACS). Pharmacodynamic effects of the platelet glycoprotein IIb/IIIa antagonist eptifibatide have been delineated in healthy subjects but not in patients with ACS. We assessed effects of eptifibatide on ex vivo platelet aggregation in patients enrolled in the Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin (eptifibatide) Therapy (PURSUIT) trial of ACS.
  
  
  RESULTS
  Patients were randomly assigned to an intravenous bolus (180 microgram/kg) and 72-hour infusion of eptifibatide (2.0 microgram/kg per minute, n=48) or placebo (n=50). We assessed correlations of plasma eptifibatide levels with receptor occupancy and inhibition of ex vivo platelet aggregation at 5 minutes and 1, 4, 24, 48, and 72 hours during treatment and 4 and 8 hours after termination of infusion. Blood was collected in buffered citrate and D-phenylalanyl-L-prolyl-L-arginine chloromethylketone anticoagulants. Although eptifibatide produced profound, prolonged inhibition of platelet aggregation during therapy, aggregation appeared to recover partially by 4 hours after the bolus. The aggregation response was greater with thrombin receptor agonist peptide versus ADP stimulation; inhibition of platelet aggregation was greater in blood samples anticoagulated with citrate versus D-phenylalanyl-L-prolyl-L-arginine chloromethylketone (PPACK). Plasma eptifibatide levels correlated significantly with receptor occupancy but not with inhibition of platelet aggregation.
  
  
  CONCLUSIONS
  A bolus and infusion of eptifibatide inhibits platelet aggregation profoundly in patients with ACS and is followed by brief, partial recovery. These results enhance our understanding of the relation between pharmacodynamic and clinical effects of eptifibatide in such patients and may have important implications for its use in percutaneous interventions.
authors.affiliation: Duke Clinical Research Institute, Durham, NC, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Tardiff
authors.forename: L K
authors.initials: LK
authors.lastname: Jennings
authors.forename: R A
authors.initials: RA
authors.lastname: Harrington
authors.forename: D
authors.initials: D
authors.lastname: Gretler
authors.forename: R F
authors.initials: RF
authors.lastname: Potthoff
authors.forename: D A
authors.initials: DA
authors.lastname: Vorchheimer
authors.forename: P R
authors.initials: PR
authors.lastname: Eisenberg
authors.forename: A M
authors.initials: AM
authors.lastname: Lincoff
authors.forename: M
authors.initials: M
authors.lastname: Labinaz
authors.forename: D M
authors.initials: DM
authors.lastname: Joseph
authors.forename: M F
authors.initials: MF
authors.lastname: McDougal
authors.forename: N S
authors.initials: NS
authors.lastname: Kleiman
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000368:Aged; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000789:Angina, Unstable / Q000097:blood / Q000188:drug therapy*; D000991:Antithrombins / Q000494:pharmacology; D003327:Coronary Disease / Q000097:blood / Q000188:drug therapy; D000077542:Eptifibatide; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000493:pharmacokinetics*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000097:blood / Q000493:pharmacokinetics*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors; D018179:Receptors, Thrombin / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000991:Antithrombins; D010446:Peptide Fragments; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D018179:Receptors, Thrombin; C082835:thrombin receptor peptide (42-47); D000244:Adenosine Diphosphate; C040308:phenylalanyl-prolyl-arginine-chloromethyl ketone; D000077542:Eptifibatide