Cypermethrin is a type II pyrethroid insecticide.1,2,3,4 It prolongs opening of sodium channels resulting in membrane depolarization and a conductance block of the insect nervous system, and point mutations in sodium channels induce cypermethrin-resistance in house flies, cockroaches, and mosquitos.3 Cypermethrin (1-1.5 mg) reduces survival of ticks (H. anatolicum) in vitro in a concentration-dependent manner.2 Topical administration of cypermethrin reduces the number of ticks on infested cattle. Cypermethrin (5 and 10 ppm) reduces survival of lice (D. ovis) in sheep fleece and prevents re-infestation in contact-challenged sheep for 7 and 19 weeks, respectively.1 It induces developmental neurotoxicities in zebrafish, increasing mortality and edema and inducing body-axis curvature when used at concentrations ranging from 50 to 200 μg/L.5 Cypermethrin (15 mg/kg twice weekly for 24 weeks) also induces Parkinson's disease-like neurodegeneration in rats, decreasing locomotor activity, dopamine production, and the number of tyrosine hydroxylase positive (TH+) neurons in the substantia nigra.4
1.Hall, C.A.The efficiency of cypermethrin (NRDC 149) for the treatment and eradication of the sheep louse Damalinia ovisAust. Vet. J.54(10)471-472(1978) 2.Sajid, M.S., Iqbal, Z., Khan, M.N., et al.In vitro and in vivo efficacies of ivermectin and cypermethrin against the cattle tick Hyalomma anatolicum anatolicum (Acari: Ixodidae)Parasitol Res.105(4)1133-1138(2009) 3.Hu, Z., Du, Y., and Dong, K.A sodium channel mutation identified in Aedes aegypti selectively reduces cockroach sodium channel sensitivity to type I, but not type II pyrethroidsInsect Biochem. Mol. Biol.41(1)9-13(2011) 4.Singh, A.K., Tiwari, M.N., Prakash, O., et al.A current review of cypermethrin-induced neurotoxicity and nigrostriatal dopaminergic neurodegenerationCurr. Neuropharmacol.10(1)64-71(2012) 5.DeMicco, A., Cooper, K.R., Richardson, J.R., et al.Developmental neurotoxicity of pyrethroid insecticides in zebrafish embryosToxicol. Sci.113(1)177-186(2010)