title: Role of short-term inhibition of factor Xa by FXV673 in arterial passivation: a study in a chronic model of thrombosis in conscious dogs.
abstract: Factor Xa (fXa) plays a pivotal role in the activation of the coagulation system during thrombosis, but, unlike GPIIb/IIIa receptor antagonists, the role of fXa inhibition in arterial passivation is not well defined. We compared the long-term antithrombotic efficacy of a direct fXa inhibitor, FXV673, and heparin after short-term infusion in conscious dogs. Dogs were instrumented surgically to induce carotid artery thrombosis by electrolytic injury. On day 1, dogs received a 3-h infusion of placebo (n = 10), FXV673 (100 microg/kg + 10 microg/kg/min, n = 7), or heparin (60 U/kg + 0.7 U/kg/min, n 7). Injury (100 microA) was initiated concomitantly for 1 h. The procedure was repeated on day 2 with injury of 200 microA for 3 h. Carotid artery blood flow (CBF) and coagulation parameters were monitored continuously for 3 h on days 1 and 2 and for 30 min on days 3, 4, and 5. On day 1 at 3 h, CBF in the placebo-treated group was 26% of baseline with 70% incidence of occlusion. None of the vessels occluded in the heparin and FXV673 groups; however, the CBF was significantly higher in the FXV673 group (92+/-8 ml/min versus 39+/-12 ml/min). Before injury on day 2, CBF recovered in all groups to 71-89% of baseline. After the second injury, all vessels in the placebo-treated group progressed to complete occlusion by 3 h. CBF was significantly higher in FXV673 group compared with heparin throughout the 3-h period. On days 3, 4, and 5 the placebo-treated vessels remained occluded, but the CBF in the heparin group was 33+/-20 ml/min, 55+/-11 ml/min and 68+/-12 ml/min, respectively, compared with 84+/-10 ml/min, 98+/-7 ml/min, and 99+/-10 ml/min in the FXV673 group. The arterial thrombus mass was significantly lower in FXV673 group (13+/-4 mg) compared with placebo (103+/-10 mg) and heparin (44+/-11 mg). In summary, these data demonstrate that short-term infusion of FXV673 was associated with long-term efficacy that was superior to standard heparin and underscore the role of direct fXa inhibition in arterial passivation.
authors.affiliation: Aventis Pharmaceuticals, Collegeville, Pennsylvania, USA. sam.rebello@aventis.com
authors.forename: S S
authors.initials: SS
authors.lastname: Rebello
authors.forename: C J
authors.initials: CJ
authors.lastname: Kasiewski
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: R G
authors.initials: RG
authors.lastname: Bentley
authors.forename: S R
authors.initials: SR
authors.lastname: Morgan
authors.forename: V
authors.initials: V
authors.lastname: Chu
authors.forename: D
authors.initials: D
authors.lastname: Colussi
authors.forename: K
authors.initials: K
authors.lastname: Brown
authors.forename: M H
authors.initials: MH
authors.lastname: Perrone
authors.forename: R J
authors.initials: RJ
authors.lastname: Leadley
mesh_terms: D000818:Animals; D002341:Carotid Artery Thrombosis / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology*; D003243:Consciousness / Q000187:drug effects / Q000502:physiology; D003497:Cyclic N-Oxides / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D004195:Disease Models, Animal; D004285:Dogs; D065427:Factor Xa Inhibitors; D005260:Female; D005343:Fibrinolytic Agents / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology
chemical_list: D003497:Cyclic N-Oxides; D065427:Factor Xa Inhibitors; D005343:Fibrinolytic Agents; D011725:Pyridines; C435830:otamixaban