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IUPAC name
3D model (JSmol)
ECHA InfoCard 100.007.840
Molar mass 171.627
Main hazards Toxic
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Crimidine is a convulsant poison used as a rodenticide. Crimidine was originally known by its product name, Castrix. It was originally produced in the 1940s by the conglomerate, IG Farben. [1] It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.[2] It is also no longer used in the United States as a rodenticide, but is still used to this day in other countries.

Mechanism of action[edit]

Crimidine is a promiscuous compound. It effects and inhibits various receptors and even corrupts some naturally occurring biochemicals. One of the main problems with crimidine is that it inhibits vitamin B6, which is used in the metabolism of carbohydrates and amino acids. This is due to the pyrimidine ring that both compounds contain. Although, the exact mechanism of how crimidine antagonizes vitamin B6 is unknown. Another major problem with crimidine is its effect on acetylcholinesterase, it serves as an antagonist. [3]

Crimidine AchE2.png

The serine residue, which is part of the acetylcholinesterase, acts a nucleophile and eventually replaces the chlorine group that is present in crimidine. Unlike when acetylcholine does this, the resulting serine-crimidine bond does not easily hydrolyze, causing a more permanent complex. This in turn disrupts the acetylcholine from degrading as it normally would.


Crimidine is a fast acting convulsant, with an LD50 of 5mg/kg. Earliest symptoms can develop within 20-40 minutes. These symptoms can include burning, irritation, and itching at the site of exposure or intake. Following these initial symptoms, convulsions follow and can be fatal. Low dose, long-term exposure can lead to damage in the central nervous system, resulting in muscle stiffness, restlessness, and sensitivity to light and noise. [4] Although crimidine is fast acting, it is also quickly secreted and can pass through the system in less than 24 hours.


Although cases with human poisoning via crimidine is small, several cases exist with curing rats, dogs, and other various mammals. In many cases pyridoxine (Vitamin B6) has been used to treat crimidine poisioning.


  1. ^ Reigart, J. Routt; Roberts, James R. (2013). "Rodenticides". Recognition and Management of Pesticide Poisoning: 173–187. 
  2. ^ "40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities" (PDF) (July 1, 2008 ed.). Government Printing Office. Retrieved October 29, 2011. 
  3. ^ Murakami, Yoichi (1972). "On the Convulsive action of Castrix". Biochemical Pharmacology: 277–280. 
  4. ^ "Crimidine". U.S. National Library of Medicine, National Institutes of Health. 2016.