Cypermethrin

Structural formula
Structural formula without stereochemistry
General
Non-proprietary name	Cypermethrin
other names	( R , S ) -α-Cyano-3-phenoxybenzyl- (1 RS ) - cis, trans -3- (2,2-dichlorovinyl) -2,2-dimethylcyclopropane-carboxylate
Molecular formula	C 22 H 19 Cl 2 NO 3
External identifiers / databases
CAS number 52315-07-8 (unspecified stereochemistry) 66841-24-5 ([(1 R ) -1α ( R *), 3β] isomer) EC number 257-842-9 ECHA InfoCard 100.052.567 PubChem 2912 ChemSpider 2809 Wikidata Q412024
Drug information
ATC code	P03 BA02 Q P53AC08
Drug class	insecticide
Mechanism of action	Opening of the Na + channels
properties
Molar mass	416.30 g mol −1
Physical state	firmly
density	1.25 g cm −3 (20 ° C)
Melting point	81 ° C
solubility	heavy in water (1 mg l −1 at 20 ° C)
safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 301-332-315-317-335-373-410 P: 260-280-301 + 330 + 331 + 310-312-405-501
Toxicological data	79 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cypermethrin is an insecticide from the pyrethroids group . It is used as a mixture of isomers.

It was developed by the group of Michael Elliott ( Rothamsted Research ) and is a Type II pyrethroid.

Stereochemistry

Cypermethrin contains three stereocenters and thus consists of eight stereoisomers . The technical product is a mixture of ( R , R , R ) -, ( R , R , S ) -, ( S , R , S ) -, ( R , S , S ) -, ( R , S , S ) -, ( S , R , S ) -, ( S , S , R ) - and ( S , S , S ) -form.

Mode of action

Cypermethrin is a contact poison and also has an insect repellent effect. It is administered either in the form of prepared ear tags (here the repellant effect predominates) or as an infusion. Within a few hours, it spreads over the animal's body via sweat and sebum .

Insects ingest cypermethrin through the body surface, whereupon it is distributed throughout the insect's body. It is a neurotoxin and causes the Na ⁺ channels of the nerve cells to no longer close. Na ⁺ ions flow unhindered into the inside of the cell and uncontrollable nerve impulses occur. This initially leads to states of excitement with cramps, then to coordination disorders and finally to paralysis. The insect is unable to move within a few minutes, which is known as a "knock-down effect". The repellant effect is based on the irritation of tactile elements in the extremities (“foot retraction effect”) of the arthropods .

Death only occurs after a while. Ticks are killed within two days. The effects of Cypermethrin last for 2 weeks to 5 months.

If the dose is insufficient, many of the insects affected can break down cypermethrin enzymatically (detoxification esterases and mixed function oxidases ). By adding synergists such as piperonyl butoxide , enzymatic degradation can be prevented.

Areas of application

Veterinary medicine : Cypermethrin is used to repel and combat stinging, biting and sucking-licking insects. In ruminants is the active ingredient against ticks , horn flies ( Haematobia spp.), Head flies ( Musca autumnalis ), brakes , lice and lice , in pigs and horses against lice and in poultry against bird lice , Trichostrongylus , bird mites and fleas effective. In fish, cypermethrin can be used as a seawater bath. According to Regulation (EEC) No. 2377/90 on maximum levels for veterinary medicinal product residues in food , the active substance is approved in Annex I for ruminants and trout fish . The maximum permissible residue level in meat is 20 µg / kg for ruminants and 50 µg / kg for trout.

Wood protection : In the wood preservative industry, cypermethrin is used as a biocide in combating and preventive wood preservatives , since October 3, 2013 also in renewed approval as an old active substance under the Biocidal Products Directive 98/8 EC or in its renewal, the regulation ( EU) No. 528/2012 (biocide regulation) .

Agriculture : Cypermethrin is approved as an active ingredient in crop protection products in the European Union. In Germany and Austria, preparations containing cypermethrin are used in forestry as well as in arable and vegetable growing. Preparations for use in the home garden are also available in Switzerland. If felled wood is stored in the forest, it is often treated with cypermethrin. This also applies to FSC-certified forests.

Private consumers and professional pest control: Cypermethrin is often found in combination with other pyrethroids in household insecticides and is used in professional pest control. Like all pyrethroids , cypermethrin is long-lasting and resistant to cleaning. Cypermethrin can remain in households for years because the rate of breakdown is significantly longer than in the wild, for example in arable farming. Providers postulate a duration of action of the agents of 6-18 weeks, which, however, must be considered too short. Repeated use can lead to significantly increased concentrations in the long term in closed areas. Cypermethrin collects in house dust even when used once on sprayed surfaces and is thus also distributed on untreated surfaces (cross contamination). Since cypermethrin is almost insoluble in water, it can only be removed with surfactants and high mechanical effort, whereby the success of the decontamination also depends heavily on the porosity of the surfaces (e.g. smooth tiles vs. joints, silicone or wood) and it is essential that a sprayed surface cannot absorb and thus store the agent (this also applies to all pyrethroids).

Trade names

Agriculture:

• Fastac Forest
• Cymbush

Veterinary medicine:

• Ektomin 100 EC ad us. vet.
• Flectron ( combination preparation with permethrin )

Cypermethrin is also available as an over-the-counter insecticide to combat ants and cockroaches as well as other insects (Bertram Cockroach Gel, Compo Ant Spray, Contra Insect Plus, Detia-Degesch Cockroach Gel, Fastac, Fendona, Raid Ant Spray, Ripcord, Tenopa, Ardap concentrate).

Web links

• Entry to cypermethrin at Vetpharm

Individual evidence

1. ↑ ^{a b c d} Entry on cypermethrin cis / trans ± 40/60 in the GESTIS substance database of the IFA , accessed on January 8, 2018(JavaScript required) .
2. ↑ ^{a b} entry on cypermethrin. In: Römpp Online . Georg Thieme Verlag, accessed on November 11, 2014.
3. ↑ Entry on α-cyano-3-phenoxybenzyl 3- (2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can use the expand harmonized classification and labeling .
4. ↑ Cypermethrin. Pesticide Information Profiles. In: Extension Toxicology Network (EXTOXNET). Oregon State University, June 1996, accessed December 9, 2019 . 
5. ↑ Implementing Regulation (EU) No. 945/2013 of the Commission of October 2, 2013 for the approval of cypermethrin as an old active ingredient for use in biocidal products of product type 8 .
6. ↑ Regulation (EU) No. 528/2012 of the European Parliament and of the Council of May 22, 2012 on the making available on the market and the use of biocidal products .
7. ↑ General Directorate Health and Food Safety of the European Commission: Entry on cypermethrin in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 20, 2016.
8. ↑ Stefanie Wermelinger: In the Swiss forest highly toxic insecticide is sprayed. In: naturschutz.ch. April 8, 2019, accessed May 2, 2019 . 
9. ↑ Hannes Weber: Much more poison is sprayed in the Zurich forest. In: tagesanzeiger.ch . May 10, 2019, accessed September 9, 2019 . 
10. ↑ Bayer. State Office for Environmental Protection (event): Pest control in the house and garden (Augsburg 07.07.2005), Augsburg, 2005. Accessed in 2020 . 
11. ↑ Study of Insecticide Concentrations. Accessed in 2005 . 
12. ↑ Decontamination of insecticides. Accessed in 2009 . 
13. ↑ headlice.org: Signs & Symptoms of Pesticide Poisoning

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !