bifenthrin and ethofenprox

Topics: Chromatography, High Pressure Liquid; Insecticides; Limit of Detection; Liquid Phase Microextraction; Nitriles; Pyrethrins; Signal-To-Noise Ratio; Surface-Active Agents; Temperature; Water Pollutants, Chemical

Five insecticides (Bifenthrin, Deltamethrin, Etofenprox, Permethrin and Lamda cyhalothrin) recommended by WHO, at their recommended dose were compared for their efficacy and wash resistance through bioassay against mosquito vectors, Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. Etofenprox treated nettings exhibited better knockdown and mortality than the other insecticides. The order of efficacy of the insecticides treated nettings was Etofenprox > or = Deltamethrin > Lambda cyhalothrin > Permethrin > Bifenthrin.

Topics: Aedes; Animals; Anopheles; Culex; Insect Vectors; Insecticides; Mosquito Control; Mosquito Nets; Nitriles; Pyrethrins; Species Specificity; Time Factors

Four commonly used pyrethroids (permethrin, bifenthrin, ethofenprox, and fenpropathrin) were orally administered to Sprague-Dawley rats for 5 days to study their effects on the liver cytochrome P450 (CYP) activities. Also Michaelis-Menten kinetics of the metabolic reactions catalyzed by liver CYPs were examined after adding these pyrethroids to the assay system to investigate their possible inhibitory effects on liver CYPs activities. These reactions included ethoxyresorufin O-deethylation, tolbutamide hydroxylation, bufuralol 1'-hydroxylation, and midazolam 4-hydroxylation, for CYP1A, 2C, 2D, and 3A activities, respectively. Results showed that oral administration of bifenthrin and ethofenprox highly induced CYP1A. The most potent inhibitors for CYP1A were fenpropathrin and cis-permethrin with K(i) values of 3.71 & 3.87 microM, respectively. CYP2D was slightly inhibited by both of fenpropathrin and cis-permethrin (K(i) values were 307.32 & 632.23 microM, respectively). On the other hand, none of CYP2C or 3A was inhibited by the tested pyrethroids. Since CYP1A may relate to biotransformation of many chemicals to reactive metabolites, bifenthrin and ethofenprox may potentiate mutagenicity of the chemicals through their inducing effects on CYP 1A. As permethrin and fenpropathrin were potent inhibitor for CYP1A, they may result in substantial accumulation of some chemicals. The resultant accumulation may lead to fatal toxicities in some case.

Topics: Administration, Oral; Animals; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Kinetics; Male; Microsomes, Liver; Permethrin; Pyrethrins; Rats; Rats, Sprague-Dawley; Substrate Specificity