Sub-acute compounds

These are no anticoagulants, but compounds belonging to different modes of action. They do not act very quick, but with some delay up to a few days.

Bromethalin was developed in the 1970s. It is a single-feeding rodenticide that is registered for use in the USA, where its use is restricted to bait stations in and around buildings for the control of commensal rodents. In the 1970s, bromethalin was evaluated for use in Europe; however, because of concerns regarding humaneness, the dossier was not submitted and bromethalin is not registered in Europe. Bromethalin is a neuro-toxicant. The use of this substance is increasing in the USA because of the recent removal of the second-generation anticoagulants from the amateur market.

Cholecalciferol (vitamin D3) was developed as a rodenticide in the 1970s. It has a relatively low risk of secondary poisoning and low toxicity to birds. In New Zealand it is registered in baits at 0.4 and 0.8% and in the USA at 0.075%. In Europe it was registered at 0.1% but this registration has lapsed, although re-registration is under consideration. Time to death is similar to that for anticoagulants and usually occurs 3-7 days after a lethal dose. To become biologically and toxicologically active, cholecalciferol must undergo metabolic conversion to 25-hydroxycholecalciferol. The latter metabolite is the most biologically active form of vitamin D3 which can cause calcification of blood vessels and death from heart failure. Low doses of cholecalciferol have been added to anticoagulant containing baits to increase their effectiveness. There is some proof that low doses of cholecalciferol added to anticoagulants like coumatetralyl can significantly increase the efficacy of the FGAR in resistant Norway rats.