title: Combination therapy with tirofiban and enoxaparin in acute coronary syndromes.
abstract: BACKGROUND
  Tirofiban, an intravenous glycoprotein IIb/IIIa antagonist, and enoxaparin, a low molecular weight heparin, have each been shown to be effective at reducing cardiac ischemic events compared to unfractionated heparin alone in separate trials of patients with unstable angina and non-Q-wave myocardial infarction. The combination of these agents may offer further therapeutic benefit.
  
  
  METHODS
  Fifty-five patients with non-Q-wave myocardial infarction were randomized to receive double-blind treatment with tirofiban (0.1 microgram/kg/min i.v.) for 48-108 h coadministered with either enoxaparin (1 mg/kg sc q 12 h) (n=26) or unfractionated heparin (i.v. adjusted to activated partial-thromboplastin time) (n=27) to evaluate pharmacokinetics, pharmacodynamics, and safety. The primary objective of the study was to investigate the effect of unfractionated heparin versus enoxaparin on the plasma clearance of tirofiban.
  
  
  RESULTS
  Coadministration of tirofiban and enoxaparin was generally well tolerated. Plasma clearance of tirofiban was 176.7+/-59.8 and 187.5+/-81.8 ml/min, respectively, for enoxaparin and unfractionated heparin-treated patients (P=NS). The mean difference was well within the prespecified criterion for comparability. Administration of tirofiban with enoxaparin vs. unfractionated heparin resulted in lesser variability and a trend towards greater inhibition of platelet aggregation using 5 microM adenosine phosphate agonist. More patients achieved target inhibition of platelet aggregation >70% in the tirofiban and enoxaparin group (84% vs. 65%, P=0.19). Median bleeding time was 21 min for tirofiban and enoxaparin vs. > or =30 min for tirofiban and unfractionated heparin (P=NS). For a given level of inhibition of platelet aggregation, bleeding time was less prolonged with tirofiban and enoxaparin than tirofiban and unfractionated heparin (adjusted mean bleeding time 19.6 vs. 24.9 min, P=0.02). Tirofiban plasma concentration and clearance were comparable whether coadministered with enoxaparin or unfractionated heparin. There were no major or minor bleeding events in either group by the TIMI criteria.
  
  
  CONCLUSIONS
  The more consistent inhibition of platelet aggregation and lower adjusted bleeding time of tirofiban and enoxaparin vs. tirofiban and unfractionated heparin support the therapeutic potential of combining these two agents. These data from the first clinical report of coadministration of a glycoprotein IIb/IIIa receptor antagonist and a low molecular weight heparin are consistent with prior data which show differential pharmacodynamic effects of enoxaparin and unfractionated heparin on platelet aggregation.
authors.affiliation: Hahnemann University Hospital, Philadelphia, PA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Cohen
authors.forename: P
authors.initials: P
authors.lastname: Théroux
authors.forename: S
authors.initials: S
authors.lastname: Weber
authors.forename: P
authors.initials: P
authors.lastname: Laramée
authors.forename: T
authors.initials: T
authors.lastname: Huynh
authors.forename: S
authors.initials: S
authors.lastname: Borzak
authors.forename: J G
authors.initials: JG
authors.lastname: Diodati
authors.forename: I B
authors.initials: IB
authors.lastname: Squire
authors.forename: L I
authors.initials: LI
authors.lastname: Deckelbaum
authors.forename: A R
authors.initials: AR
authors.lastname: Thornton
authors.forename: K E
authors.initials: KE
authors.lastname: Harris
authors.forename: F L
authors.initials: FL
authors.lastname: Sax
authors.forename: M W
authors.initials: MW
authors.lastname: Lo
authors.forename: H D
authors.initials: HD
authors.lastname: White
mesh_terms: D000789:Angina, Unstable / Q000097:blood / Q000000981:diagnostic imaging / Q000188:drug therapy*; D017023:Coronary Angiography; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D017984:Enoxaparin / Q000008:administration & dosage / Q000627:therapeutic use*; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D006493:Heparin / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D007275:Injections, Intravenous; D009203:Myocardial Infarction / Q000097:blood / Q000000981:diagnostic imaging / Q000188:drug therapy*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors*; D012449:Safety; D013577:Syndrome; D000077466:Tirofiban; D016896:Treatment Outcome; D014443:Tyrosine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D017984:Enoxaparin; D005343:Fibrinolytic Agents; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D014443:Tyrosine; D006493:Heparin; D000077466:Tirofiban