Vitamin anticoagulant poisoning

The isoprene-derived molecule whose structure is shown here is known alternately as Coumarin and warfarin. By the former name, it is a widely prescribed anticoagulant. By the latter name, it is a component of rodent poisons. How can the same chemical species be used for such disparate purposes The key to both uses lies in its ability to act as an antagonist of vitamin K in the body. 

Vitamin K antagonists, such as dicoumarol (8.61, a natural product) and warfarin (8.62), are used as anticoagulants in human therapy (thrombosis, atherosclerosis) and as rat poisons that lead to internal bleeding and death in rodents. Heparin, a polysaccharide consisting of 2-0-sulfonated glucuronic acid and 2-N,6-0-disulfonated glucosamine, is also a widely used anticoagulant, but its effect is connected not with Vitamin K but with enzyme inhibition. 

Robben, J.H., Kuijpers, E.A., Mout, H.C. (1998). Plasma superwarfarin levels and vitamin K1 treatment in dogs with anticoagulant rodenticide poisoning. Vet. Q. 20(1) 24-7. 

Indeed, after appropriate sample preparation, standards and samples can be spotted or sprayed onto the same plate, thereby providing a rapid and cost-effective analytical procedure to evaluate all sampling times. If an ultraviolet (UV) scanner is used, it is also possible to determine the amount of substance for each sample. Furthermore, the UV scanner sensitivity may be adapted specifically to analyze highly concentrated samples and poorly concentrated ones on the same plate, provided the calibration curve includes the values. As an example. Fig. 1 presents some kinetic data obtained for vitamin K, which is used as an antidote in dogs suffering from anticoagulant rodenticide poisoning [2]. The method was developed on Ci8-coated silica gel plates. Elution was based... 

Warfarin and dicoumarol are used clinically as anticoagulants. Warfarin is also a common rat poison, causing death by internal bleeding. These compounds prevent clotting by inhibiting the enzyme that reduces vitamin K epoxide to vitamin KH2, thereby preventing the carboxylation of glutamate. The enzyme caimot tell the difference between these two compounds and vitamin K epoxide, so the compounds act as competitive inhibitors. 

Activity D. inhibits vitamin K epoxide reductase and thus the synthesis of the blood clotting factor prothrombin. D. acts as an anticoagulant (vitamin K antagonist). D. and its analogues (e.g., warfarin, pben-procoumon) are used clinically for thrombosis thnsqry. It causes tissue and skin hemorrhages in rodents and thus finds use as a rat poison. For the mechanism of action, see L/r.. LD50 (rat p.o.) 541.6 mg/kg. lit . Am. Chem. Soc. 1 3.3910-3915 (1981) Nat Plod. Rep. 11,591-606(1994). 

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