The Effect of Human Recombinant Tissue-Type Plasminogen Activator on Clinical and Laboratory Parameters of Hemostasis and Systemic Plasminogen Activation in the Dog and the Rat

Abstract

SummaryThe effect of human recombinant tissue-type plasminogen activator (rt-PA) on parameters of hemostasis and systemic plasminogen activation was studied in the dog and rat. Effects on screening coagulation times, fibrinogen concentration, fibrin/fibrinogen degradation products, and plasminogen and α2-anti- plasmin (α2-AP) activities in plasma were examined following single bolus injections of 0.5-5.0 mg/kg, single and repeated 3 hr infusions of 0.75-7.5 mg/kg and 24 hr infusions of 6.0 and 30.0 mg/kg administered intravenously to dogs. Rats receiving single or 14 daily injections of 5.0-30.0 mg/kg i.v. were similarly monitored. Systemic fibrinogenolysis (>50% decrease in fibrinogen, plasminogen or α2-AP values) was observed in dogs receiving ≥1.0 mg/kg as a bolus, ≥3.75 mg/kg (20.8 μg or 1.19 × 104 IU kg−1min−1) as a 3 hr infusion and >6 mg/kg (4.2 μg or 2.42 × 103IU kg−1min−1) as a 24 hr infusion; and in rats treated with bolus injections of 30 mg/kg rt-PA. Clinical and laboratory indications of impaired hemostasis and bleeding (anemia, prolonged coagulation times and post-mortem evidence of hemorrhage) were associated with these effects, which together were dose-dependent and influenced by the rate of infusion. The incidence of major hemorrhage was variable and limited to animals receiving prolonged (24 hr) or repeated infusions.