Products
Difenacoum is found in mouse and rat poisons (e.g., Gesal Protect rat and mouse bait). It has been available since the 1970s.
Structure and properties
Difenacoum is a (C31H24O3, Mr = 444.5 g/mol) is a 4-hydroxycoumarin, warfarin, and biphenyl derivative. It was developed to overcome resistance to warfarin (“superwarfarin”). Difenacoum is structurally closely related to brodifacoum, which is brominated. Difenacoum exists as a white powder and is sparingly soluble in water. The melting point is about 215°C.
Effects
Difenacoum has rodenticidal properties. The effects are based on indirect inhibition of blood clotting through decreased formation of active blood clotting factors. Difenacoum inhibits the enzyme vitamin K epoxide reductase (VKOR). In addition, it also damages blood vessels, increasing permeability and causing internal bleeding. The lethal effect is delayed after a few days. This is an advantage because other rodents cannot infer the cause of the poisoning. Difenacoum has a more potent effect and a longer half-life than the precursor warfarin.
Indications for use
As a mouse and rat poison. Difenacoum may also be used for other mammals.
Abuse
Difenacoum can theoretically be abused for suicide and for poisoning. The toxic effects are delayed in onset. However, the agent is present in the bait at a low concentration (0.005%).
Dosage
According to the directions for use. Check bait sites daily and replace the agent until it is no longer eaten.
- Wear gloves when setting out (can enter the body through the skin).
- Must not get into the hands of children.
- Lay out out of reach of pets, children and birds.
- Check the bait sites regularly.
- Collect dead mice and rats.
- Keep separate from food and drink and do not eat or drink when put out.
- Dispose of properly and do not allow to enter water.
Adverse effects
In case of accidental ingestion, life-threatening poisoning with bleeding is possible. Children, pets, birds, fish and livestock are particularly at risk. Animals such as owls can be secondarily poisoned if they eat contaminated mice. Activated charcoal and vitamin K1 are used as antidotes. A problem is the occurrence of hereditary resistance, which can develop in response to selection pressure. Mice and rats with a mutant variant of the enzyme vitamin K epoxide reductase are selected when the toxin is administered.
