Thrombolysis with intracoronary administration of YM866, a novel modified tissue-type plasminogen activator, in a canine model of coronary artery thrombosis

2022 Update of the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) Domain 6: Defining rational use of thrombolytics

OBJECTIVES

To systematically review available evidence and establish guidelines related to the use of thrombolytics for the management of small animals with suspected or confirmed thrombosis.

DESIGN

PICO (Population, Intervention, Control, and Outcome) questions were formulated, and worksheets completed as part of a standardized and systematic literature evaluation. The population of interest included dogs and cats (considered separately) and arterial and venous thrombosis. The interventions assessed were the use of thrombolytics, compared to no thrombolytics, with or without anticoagulants or antiplatelet agents. Specific protocols for recombinant tissue plasminogen activator were also evaluated. Outcomes assessed included efficacy and safety. Relevant articles were categorized according to level of evidence, quality, and as to whether they supported, were neutral to, or opposed the PICO questions. Conclusions from the PICO worksheets were used to draft guidelines, which were subsequently refined via Delphi surveys undertaken by the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) working group.

RESULTS

Fourteen PICO questions were developed, generating 14 guidelines. The majority of the literature addressing the PICO questions in dogs is experimental studies (level of evidence 3), thus providing insufficient evidence to determine if thrombolysis improves patient-centered outcomes. In cats, literature was more limited and often neutral to the PICO questions, precluding strong evidence-based recommendations for thrombolytic use. Rather, for both species, suggestions are made regarding considerations for when thrombolytic drugs may be considered, the combination of thrombolytics with anticoagulant or antiplatelet drugs, and the choice of thrombolytic agent.

CONCLUSIONS

Substantial additional research is needed to address the role of thrombolytics for the treatment of arterial and venous thrombosis in dogs and cats. Clinical trials with patient-centered outcomes will be most valuable for addressing knowledge gaps in the field.

[Effects of fraction from Phyllanthus urinaria on thrombosis and coagulation system in animals]

OBJECTIVE

To investigate the effects of PUW (a fraction containing 60% corilagin from a Chinese herbal plant Phyllanthus urinaria) on thrombosis and coagulation system.

METHODS

Myers's method was used to evaluate the protection of intravenously administered PUW against the male mouse sudden death caused by injection of 75 mg/kg arachidonic acid in the tail vein; Charlton's method was modified to observe antithrombotic effect of PUW in rat electrically stimulated carotid artery thrombosis model; and the model of venous thrombosis was produced to investigate the antithrombotic effect of PUW. Rosette assay was used to observe the effect of PUW on platelet-neutrophil adhesion. The effects of PUW were monitored on euglobulin lysis time (ELT), prothrombin time (PT), kaolin partial thromboplastin time (KPTT), and bleeding time (BT) in rats, according to the methods of Kowalski, HUANG Zheng-Liang, and GU Yue-Fang, et al, respectively.

RESULTS

The results showed that PUW administered intravenously significantly decreased the mouse mortality, prolonged the occlusion time of rat carotid arteries, and reduced the wet and dry thrombus weight of the inferior vena cava, respectively. PUW markedly inhibited the binding of activated platelets to neutrophils, obtaining 39.7 mg/L of the medium inhibitory concentration. Intravenously administered PUW significantly shortened ELT, prolonged KPTT while had no influence on PT; PUW increased BT in rat tail tips but the BT caused by PUW was much shorter than that by aspirin or urokinase.

CONCLUSION

It is suggested that PUW has the potential of antithrombosis due to its inhibition of platelet-neutrophil adhesion. PUW shows the tendency to bleeding, however, it could not cause serious bleeding side effect as compared with aspirin or urokinase.

Pharmacokinetic properties of a novel tissue-type plasminogen activator pamiteplase after single intravenous administration to rats, dogs, and monkeys

The pharmacokinetics of pamiteplase and recombinant tissue-type plasminogen activator (rt-PA) in rats, dogs, and monkeys were examined using a newly developed enzyme-linked immunosorbent assay (ELISA). Plasma concentrations after intravenous administration of pamiteplase to rats declined in a triphasic manner. Plasma concentrations after intravenous administration of pamiteplase to dogs or monkeys declined in a biphasic manner. The area under the plasma concentration-time curve from zero to infinity (AUC(0-->infinity)) in rats and dogs increased with increasing dose. The half-life and mean residence time of pamiteplase in rats, dogs, and monkeys were shown to be longer than those of rt-PA. Total clearance (CL(total)) of pamiteplase was only 7-16% that of rt-PAs, suggesting that concentrations of pamiteplase in plasma were higher and more continuous than those of rt-PA in these experimental animals. The data suggest that a bolus administration of pamiteplase shows the same thrombolytic activity as continuous infusion of rt-PA in experimentally induced thrombosis in rats and dogs. The pharmacokinetic parameters distribution volume at the steady state and CL(total) calculated by immunoreactive concentration after administration of pamiteplase to rats, dogs, and monkeys show high correlation with body weights (r(2)=.7728 and .9039).

YM866, a novel modified tissue-type plasminogen activator, affects left ventricular function and myocardial infarct development in dogs with coronary artery thrombi

YM866 is a novel modified tissue-type plasminogen activator (t-PA). Its effects on left ventricular function and myocardial infarct development in dogs with copper coil-induced coronary artery thrombosis were compared with those of a native t-PA, alteplase. YM866 (bolus injection) and alteplase (bolus plus infusion) were administered 15 min after coronary artery occlusion. YM866 and alteplase produced reperfusion in all animals, with a median time to reperfusion of 10 min. In contrast, no reperfusion occurred in the vehicle control group. Left ventricular ejection fraction (LVEF) significantly decreased 15 min after coronary occlusion. YM866 and alteplase improved LVEF 3 hr and 4 hr after administration, respectively, while LVEF did not improve in the vehicle control group. Only slight myocardial infarct areas were observed in both YM866- and alteplase-administered groups, while the area in the vehicle control group accounted for 18.2% of left ventricular myocardial area. In conclusion, although both YM866 and alteplase reperfused occluded coronary arteries, inhibited myocardial infarct development and improved LVEF in dogs with coronary artery thrombi, only a single bolus injection of YM866 was necessary to achieve these improvements. Therefore, YM866 shows promise as an improved clinical agent in treating acute myocardial infarction.