Thrombin generation test: A reliable tool to evaluate the pharmacodynamics of vitamin K antagonist rodenticides in rats

Pestic Biochem Physiol. 2018 Apr;146:19-24. doi: 10.1016/j.pestbp.2018.02.004. Epub 2018 Feb 15.

Abstract

Vitamin K antagonist rodenticide pharmacodynamics (PD) is studied in rodents with traditional laboratory tests. We wondered if thrombin generation test (TGT) could add value. Difethialone (10 mg/kg) was administered per os to 97 OFA-Sprague Dawley rats. PD was studied over a 72 h-period using the Calibrated Automated Thrombogram on platelet poor plasma before and after intoxication (3 female and 3 male rats for each 13 time points) and TGT parameters were compared with the prothrombin time (PT) and vitamin K dependent factor activities previously reported. Following intoxication, preliminary tests evidenced rapid and full inhibition of thrombin generation triggered with 5 or 20 pM human recombinant tissue factor. To study the evolution of TGT parameters following difethialone intake, we adapted the test by complementing intoxicated rat samples with pooled normal rat plasma (3/1, v/v). Adapted TGT confirmed the known higher procoagulant basal level in females compared to males through higher endogenous thrombin potential (ETP) and peak height (PH) (p < 0.0001 and p = 0.0003, respectively). An exponential model fitted well the PH and ETP decay after intoxication. In contrast to PT, the decreases were observed immediately following VKA intake and had comparable time to halving values: 10.5 h (95% CI [8.2; 13.6]) for ETP and 10.4 h (95% CI [7.8; 14.1]) for PH. The decrease of FVII and FX preceded that of PH, ETP and FII while FIX decreased later on, contributing to the severe hypo-coagulability. We demonstrated that TGT performed in samples of intoxicated rats complemented with normal plasma is a reliable tool for evaluation of VKA rodenticide PD in rats.

MeSH terms

  • 4-Hydroxycoumarins / pharmacology*
  • 4-Hydroxycoumarins / poisoning
  • Animals
  • Anticoagulants / pharmacology*
  • Anticoagulants / poisoning
  • Blood Coagulation Factors / metabolism
  • Blood Coagulation Tests
  • Female
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Rodenticides / pharmacology*
  • Rodenticides / poisoning
  • Thrombin / biosynthesis*
  • Vitamin K / antagonists & inhibitors*

Substances

  • 4-Hydroxycoumarins
  • Anticoagulants
  • Blood Coagulation Factors
  • Rodenticides
  • Vitamin K
  • Thrombin
  • difethialone