Antithrombotic effects of MK-0852, a platelet fibrinogen receptor antagonist, in canine models of thrombosis.
The antiaggregatory and antithrombotic actions of MK-0852, a cyclic heptapeptide antagonist of the platelet GP IIb/IIIa, were evaluated in a variety of canine models. In vitro, MK-0852 inhibited the aggregation of canine platelet-rich plasma induced by 10 microM ADP in the presence of 1 microM epinephrine with an IC50 value of 0.10 microM. The i.v. infusion of 1.0 and 3.0 micrograms/kg/min MK-0852 to anesthetized dogs significantly inhibited ex vivo platelet aggregation responses to ADP and collagen, with the 3.0 micrograms/kg/min infusion completely inhibiting ex vivo aggregation responses to both agonists. The i.v. administrations of 100 and 300 micrograms/kg MK-0852 suppressed platelet-dependent cyclic flow reductions in stenosed canine left circumflex (LCX) coronary artery for periods of 24 +/- 3 and 64 +/- 4 min, respectively. In a canine model of copper coil-induced femoral arterial thrombosis, i.v. MK-0852 (100 micrograms/kg + 1 microgram/kg/min), initiated 15 min before coil placement, reduced the incidence of occlusive thrombosis during the 45-min post-coil time period of continued therapy (1/5 MK-0852 vs. 7/7 saline; P < .01). MK-0852 was administered as an adjunctive therapy with tPA to evaluate its effects on thrombolysis after copper coil-induced femoral arterial thrombus formation. MK-0852 (i.v.; 100 micrograms/kg + 1 microgram/kg/min), initiated 15 min before tPA, reduced the incidence of post-thrombolysis reocclusion. During the 60-min period of continued drug infusion after the termination of tPA, 0 of 5 animals receiving MK-0852 reoccluded vs. 7/8 saline (P < .01). In a canine model of electrically induced LCX coronary artery thrombosis, i.v. MK-0852 (100 micrograms/kg + 3 micrograms/kg/min), initiated 15 min before the initiation of electrical injury, prevented occlusive thrombosis in 4 of 6 preparations despite the continued electrical stimulation of the vessel for 180 min. Thrombotic occlusion was delayed in the remaining two preparations (99 and 100 min), compared with occlusion in 4 of 4 saline-treated preparations (69.3 +/- 6.3 min). When administered as an adjunct to thrombolytic agents for lysis of electrically induced LCX coronary artery thrombi, i.v. MK-0852 (300 micrograms/kg + 3 micrograms/kg/min), initiated 15 min before tPA or streptokinase, both increased the incidence of reperfusion (tPA: 8/8 MK-0852 vs. 3/8 saline; streptokinase: 5/8 MK-0852 vs. 2/8 saline) and accelerated reperfusion. The incidence of reocclusion during continued adjunctive therapy was reduced.(ABSTRACT TRUNCATED AT 400 WORDS)
Ramjit
D R
DR
Department of Pharmacology, Merck Research Laboratories, West Point, Pennsylvania.
Lynch
J J
JJ
Sitko
G R
GR
Mellott
M J
MJ
Holahan
M A
MA
Stabilito
I I
II
Stranieri
M T
MT
Zhang
G
G
Lynch
R J
RJ
Manno
P D
PD
D000595:Amino Acid Sequence; D000818:Animals; D001760:Bleeding Time; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology; D003328:Coronary Thrombosis / Q000097:blood / Q000188:drug therapy / Q000517:prevention & control; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D005263:Femoral Artery; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors*; D053778:Thiazolidines; D013927:Thrombosis / Q000097:blood / Q000188:drug therapy* / Q000517:prevention & control
D005343:Fibrinolytic Agents; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D053778:Thiazolidines; C083231:MK 0852