Prevention of experimental carotid and coronary artery thrombosis by the glycoprotein IIb/IIIa receptor antagonist CRL42796

Abstract

1. The antithrombotic effect of the glycoprotein IIb/IIIa receptor antagonist, CRL42796, was examined in canine models of carotid and coronary artery thrombosis. 2. In the carotid artery thrombosis model, occlusion occurred in all control vessels (time to thrombosis 47.6+/-8.9 min). After treatment with low dose CRL42796 (15 microg kg(-1) loading dose +0.31 microg kg(-1) min(-1) i.v.), two of five vessels occluded. Time to thrombosis increased significantly to 155.2+/-23.1 min. When the drug infusion was increased (0.69 microg kg(-1) min(-1)), each of five vessels remained patent. 3. Ex vivo platelet aggregation in response to arachidonic acid (AA) and ADP was examined in platelet rich plasma (PRP) prepared from citrate or heparin anticoagulated blood. CRL42796 reduced platelet reactivity at low and high doses in PRP from citrate anticoagulated blood. However, in PRP from heparin anticoagulated blood, only the higher infusion dose produced a significant reduction in ex vivo platelet responses. 4. A combination of oral aspirin (4.6 mg kg(-1) -41, -17 h) and the low infusion dose of CRL42796 did not produce an additional benefit beyond that provided by CRL42796 alone. 5. Coronary artery thrombosis was inhibited in four of five vessels treated with the lower infusion dose of CRL42796 and in five of five vessels treated with the higher infusion. Time to thrombosis increased with both doses (Control, 90.8+/-10.4 min; low dose, 165.8+/-14.2 min; high dose, >180.0+/-0 min). 6. The results indicate that CRL42796 is an effective in vivo antithrombotic agent against experimentally-induced carotid and coronary artery thrombosis.

Figure 1

The chemical structure of CRL42796, (2S)-2-[(2-naphthylsulfonyl)amino]-3-{[2-({4-(4-piperidinyl)-2-[2-(4 piperidinyl)ethyl]butanoyl}amino)acetyl]amino} propanoic acid, dihydrochloride.

Figure 2

Carotid artery blood flow during electrolytic injury in the absence and presence of CRL42796 (15 μg kg⁻¹+ 0.31 μg kg⁻¹ min⁻¹ i.v.) (a); (15 μg kg⁻¹+0.69 μg kg⁻¹ min⁻¹ i.v.) (b); and a combination of aspirin (4.6 mg kg⁻¹ −41, −17 h p.o. +15 μg kg⁻¹+0.31 μg kg⁻¹ min⁻¹ i.v.) (c). Deep vessel wall injury was initiated at time 0 and produced complete and persistent occlusion of all control carotid arteries. CRL42796 maintained carotid artery patency in all vessels for the duration of the infusion at a dose of 0.69 μg kg⁻¹ min⁻¹ i.v. and in three of five vessels at a dose of 0.31 μg kg⁻¹ min⁻¹ i.v. The combination of aspirin and the lower infusion dose of CRL42796 produced no additional benefit. Values are mean±s.e.m for n=5 experiments.

Figure 3

Effect of intravenous administration of CRL42796 on citrated ex-vivo platelet aggregation induced by AA (650 μM) and ADP (20 μM) during electrolytic injury to the carotid artery. CRL42796 was administered as a loading dose of 15 μg kg⁻¹ followed by either 0.31 μg kg⁻¹ min⁻¹ (a) or 0.69 μg kg⁻¹ min⁻¹ (b). In (c), the effect of combining aspirin (4.6 mg kg⁻¹ −41, −17 h p.o.) with the lower infusion dose of CRL42796 are shown. Values are expressed as mean±s.e.m for n=5 experiments. Asterisks indicate a significant reduction in platelet responses compared to respective baseline (P<0.05).

Figure 4

Effect of intravenous administration of CRL42796 on heparinized ex-vivo platelet aggregation induced by AA (650 μM) and ADP (20 μM) during electrolytic injury to the carotid artery. CRL42796 was administered as a loading dose of 15 μg kg⁻¹ followed by either 0.31 μg kg⁻¹ min⁻¹ (a) or 0.69 μg kg⁻¹ min⁻¹ (b). In (c), the effect of combining aspirin (4.6 mg kg⁻¹ −41, −17 h p.o.) with the lower infusion dose of CRL42796 are shown. Values are expressed as mean±s.e.m for n=5 experiments. Asterisks indicate a significant reduction in platelet responses compared to respective baseline (P<0.05).

Figure 5

Effect of CRL42796 on tongue bleeding time at baseline, after surgery, and 120 min and 225 min after intravenous administration of drug. CRL42796 was administered as a loading dose of 15 μg kg⁻¹ followed by either 0.31 μg kg⁻¹ min⁻¹ (a) or 0.69 μg kg⁻¹ min⁻¹ (b). In (c), the effect of combining aspirin (4.6 mg kg⁻¹ −41, −17 h p.o.) with the lower infusion dose of CRL42796 are shown. Values are expressed as mean±s.e.m for n=5 experiments. Asterisks indicate a significant increase in bleeding time compared to respective baseline (P<0.05).

Figure 6

Left circumflex coronary artery blood flow during electrolytic injury. Deep vessel wall injury resulted in thrombotic occlusion of all control vessels. Administration of CRL42796 maintained vessel patency in all vessels treated with a 15 μg kg⁻¹ loading dose followed by a 0.69 μg kg⁻¹ min⁻¹ i.v. infusion and in four of five vessels treated with the lower infusion dose of 0.31 μg kg⁻¹ min⁻¹ i.v. Values are expressed as mean±s.e.m for n=5 or six experiments.

Figure 7

Effect of intravenous administration of CRL42796 on citrated platelet responses to AA (650 μM) (a) and ADP (20 μM) (b) during electrolytic injury to the left circumflex coronary artery. CRL42796 was administered as a loading dose of 15 μg kg⁻¹ followed by either 0.31 μg kg⁻¹ min⁻¹ (a) or 0.69 μg kg⁻¹ min⁻¹ (b). Values are expressed as mean±s.e.m for n=5 or six experiments. Asterisks indicate a significant reduction in platelet responses compared to respective baseline (P<0.05).

Figure 8

Effect of intravenous administration of CRL42796 on heparinized platelet responses to AA (650 μM) (a) and ADP (20 μM) (b) during electrolytic injury to the left circumflex coronary artery. CRL42796 was administered as a loading dose of 15 μg kg⁻¹ followed by either 0.31 μg kg⁻¹ min⁻¹ (a) or 0.69 μg kg⁻¹ min⁻¹ (b). Values are expressed as mean±s.e.m for n=5 or six experiments. Asterisks indicate a significant reduction in platelet responses compared to respective baseline (P<0.05).

Figure 9

Effect of CRL42796 on tongue bleeding time at baseline and 120 min and 225 min after intravenous administration of drug during electrolytic injury to the left circumflex coronary artery. Values are expressed as mean±s.e.m for n=5 or six experiments. Asterisks indicate a significant increase in bleeding time compared to respective baseline (P<0.05).