Warfarin and Superwarfarins

Warfarin is a vitamin K antagonist used in medicine as oral anticoagulant. Acenocoumarin (Sinthrone) is also the vitamin K antagonist but is very rarely used in medicine. Warfarin and acenocoumarin act by inhibiting vitamin K epoxide reductase, the enzyme responsible for the reduction of vitamin K 2,3-epoxide and vitamin K quinone to vitamin K hydroquinone (the metabolically active form of vitamin K). In clinical practice, measurement of warfarin and acenocoumarin is helpful to confirm compliance in patients apparently refractory to therapy and to exclude or confirm poisoning or overdose. Another use is in the investigation of acquired warfarin resistance because of the simultaneous ingestion of drugs that upregulate anticoagulant metabolism. Conversely, the detection of high concentrations of warfarin/acenocoumarin in refractory patients may suggest hereditary resistance.
Superwarfarins are also vitamin K antagonists. They are used in public hygiene as rodenticides and can be effective against rats. Superwarfarins are highly potent compared to warfarin due to their lipophilic nature they tend to reside in the liver for prolonged periods and continue to inhibit vitamin K for many months. The ability to detect and identify the presence of superwarfarins is helpful in the clinical/forensic setting to confirm or exclude poisoning.