Permethrin synergists

Gas ehromatography mass-mass aequisition was used for the pyrethroid determination. Pyrethroids investigated were Allethrin, Prallethrin, Tetramethrin, Bifenthrin, Phenothrin, X-Cyhalothrin, Permethrin, Cyfluthrin, Cypermethrin, Flueythrinate, Fsfenvalerate, Fluvalinate and Deltamethrin. Piperonyl butoxide, main synergist eompound for pyrethroid eompounds, was also studied. 

Bioallethrin is a synthetic pyrethrin insecticide. Piperonylbutoxide, a weak insecticide itself, has synergistic activity. The same holds true for the combination of pyrethrum extract with piperonylbutoxide. These combinations have the same efficacy as permethrin. Local irritation occurs frequently effect and contact with mucous membranes and the eyes must be avoided. 

Pyrethrins and synthetic pyrethroids are among the safest of the topically applied ectoparasiticides, because of their selective toxicity for insects (mam-malian-to-insect toxic dose ratio is greater than 1000, compared with 33 for organophosphates and 16 for carbamate insecticides). In contrast to the very wide margin of safety for mammalian species, pyrethroids are toxic to fish. The synergistic action of pyrethrins and piperonyl butoxide (in combination preparations) is due to the inhibition by piperonyl butoxide of the microsomal enzyme system of some arthropods. Preparations of synthetic pyrethroids (permethrin, cypermethrin) often contain a mixture of drug isomers in varying proportions. 

PBO has not been used as an internal medicine in humans. This compound has, however been extensively used both as a synergist with pyrethrins or pyrethmids for the control of household pests and its. an agricultural insecticide. PBO has been incorporated in millions of aerosols utilized in homes, offices and factories, Furthermore. PBO has had very extensive dermal application to humans in combination with both pyre thrum and pyrethroids (e.g, permethrin) for the control of head and pubic lice, as well as scabies infestations. Such exposure has been on-going for over 40 years, with most applications being to children. The absence of untoward eHeels with the tthove uses serves to under line the wide safety margin of this compound. 

PBO is now added to commercial termite formulations based on permethrin in Japan. The PBO performs two functions firstly, it acts as a solvent so that unacceptable volatile solvents are excluded from treatments applied on or near dwelling houses and secondly, it acts as an effective but also very persistent synergist, since anaerobic conditions apply where the permethrin is impregnated in wood (see Chapter 6, this volume). 

Controversy exists over the possible role of PB. Large doses of PB can cause bromide psychosis (Rothenberg et al. 1990). The literature is conflicted as to whether a genetic variation of butyrylcholinest-erase can cause a severe reaction to PB (Loewenstein-Lichtenstein et al. 1995 Lotti andMoretto 1995 Senecal and Osterloh 1990). PB also may act synergistically with A/,A/-diethyl-m-toluamide, or DEET, an insect repellent, and permethrin, a pyrethroid insecticide. DEET, PB, and permethrin in various combinations are more neurotoxic to hens than are these agents when administered alone (Abou-Donia et al. 1996). 

Wood preservatives and agents against insects and fleas are used by more than two-thirds of the population thus their residues can be found in nearly every home. Only in two households (< 1 %) could no biocide or synergist be observed. On the other hand chlorpyriphos, propoxur and lindane were present in more than 10 %, PBO in more than 50 %, DDT, permethrin and methoxychlor in more than two-thirds and PCP in nearly every sample. Results regarding concentrations of biocides in household dust were confirmed by those obtained in Schleswig-Holstein (LANU, 1997), but information about the use of biocides indoors was not obtained for the latter study. 

Permethrin, because of its increased stabiiity and its avaiiabiiity syntheticaiiy, is not used with a synergist. The compound is used in a 1% iotion for the treatment of pedicuiosis capitis and in a 5% cream as a scabicide. 

Pyrethroids available today include allethrin, phenothrin, tetramethrin and cyphenothrin, usually for household insects control, and cypermethrin, deltamethrin, permethrin, y-cyhalothrin and cyfluthrin, mainly for agricultural insects. Pyrethroids are often commercially combined with synergist compounds like piperonyl butoxide, which enhance their insecticidal activity, or mixed with fungicides such as 2-phenylphenol or other pesticides like propoxur (a carbamate pesticide). 

Pyrethrins Some formulations contain piperonyl butoxide (synergist), A-octyl bicycloheptene dicarboximide (synergist), di-n-propyl isocinchomeronate (repellent), permethrin, carbaryl, or rotenone. The marketed formulatirms are spray, foam, dust, shampoo (0.2%), dip, or ear drops, and the target parasites are mainly fleas, ticks, mites, and lice (some products). 

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