Warfarin

Warfarin functions as an anticoagulant by interfering with the hepatic Vitamin K dependent carboxylation of prothrombin, factors VII, IX, X and the anticoagulant proteins C and S. It is rapidly absorbed orally. It binds totally to albumin in the circulation and is degraded in the liver. Most rodenticides contain coumadin or warfarin as the active ingredient. It is important to take note of the concentration of the active ingredient in every formulation. Toxicity occurs with the ingestion of 1-2 mg/kg of the substance for 3-6 days. A single intake of more than 15 grams may be lethal. Warfarin toxicity manifests in varied ways like hematuria, petecchiae, excessive menstrual bleeding or massive hemorrhage. Maximum depression of clotting factors occurs 36-72 hours post-ingestion, therefore, manifestations of bleeding may be delayed 8-12 hours after ingestion. Second generation anti-coagulants or superwarfarins, like Difenacoum or Brodifacoum are also used as rodenticides. They maybe absorbed through the intact skin. These may produce early coagulation defects which last 6-8 weeks. Thus, in these cases, bleeding may be persistent.