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PubMed2000

The effects of pyridostigmine bromide and permethrin, alone or in combination, on response acquisition in male and female rats.

It has been hypothesized that concurrent exposure to pyridostigmine bromide and permethrin may have contributed to the development of neurocognitive symptoms in Gulf War veterans. The present experiment was designed to investigate the effects of pyridostigmine bromide and permethrin alone, or in combination, on the acquisition of a novel response, one measure of normal cognitive functioning. Male and female Sprague-Dawley rats were treated with pyridostigmine bromide (1.5 mg/kg/day, by gavage in a volume of 5 ml/kg) or its vehicle for 7 consecutive days. They then also received an intraperitoneal injection of permethrin (0, 15, or 60 mg/kg) before they were exposed to an experimental session during which they could earn food by pressing a lever in an operant chamber. Serum permethrin levels increased as a function of its dose, and were higher in rats treated with pyridostigmine bromide. Sex differences were observed as permethrin levels were higher in female rats than in male rats following the highest dose. Pyridostigmine bromide delayed response acquisition in male and female rats, and resulted in higher response rates on the inactive lever in female rats than in male rats. Although permethrin levels were higher in subjects treated with pyridostigmine bromide than in those treated with vehicle, there were no differences in the behavioral effects of permethrin. Whether or not these behavioral effects of pyridostigmine bromide are of central or peripheral origin will need to be determined in future studies, as its effects on motor activity and/or gastro-intestinal motility may have affected response acquisition.

Animals↗

PubMed2005

Diffusion of the synthetic pyrethroid permethrin into bed-sediments.

Bed-sediments are a sink for many micro-organic contaminants in aquatic environments. The impact of toxic contaminants on benthic fauna often depends on their spatial distribution, and the fate of the parent compounds and their metabolites. The distribution of a synthetic pyrethroid, permethrin, a compound known to be toxic to aquatic invertebrates, was studied using river bed-sediments in lotic flume channels. trans/cis-Permethrin diagnostic ratios were used to quantify the photoisomerization of the trans isomer in water. Rates were affected by the presence of sediment particles and colloids when compared to distilled water alone. Two experiments in dark/light conditions with replicate channels were undertaken using natural sediment, previously contaminated with permethrin, to examine the effect of the growth of an algal biofilm at the sediment-water interface on diffusive fluxes of permethrin into the sediment. After 42 days, the bulk water was removed, allowing a fine sectioning of the sediment bed (i.e., every mm down to 5 mm and then 5-10 mm, then every 10 mm down to 50 mm). Permethrin was detected in all cases down to a depth of 5-10 mm, in agreement with estimates by the Millington and Quirk model, and measurements of concentrations in pore water produced a distribution coefficient (Kd) for each section. High Kd's were observed for the top layers, mainly as a result of high organic matter and specific surface area. Concentrations in the algal biofilm measured at the end of the experiment under light conditions, and increases in concentration in the top 1 mm of the sediment, demonstrated that algal/ bacterial biofilm material was responsible for high Kd's at the sediment surface, and for the retardation of permethrin diffusion. This specific partition of permethrin to fine sediment particles and algae may enhance its threat to benthic invertebrates. In addition,the analysis of trans/cis-permethrin isomer ratios in sediment showed greater losses of trans-permethrin in the experiment under light conditions, which may have also resulted from enhanced biological activity at the sediment surface.

Bacteria↗

PubMed2006

Enantiomeric differences in permethrin degradation pathways in soil and sediment.

Chirality occurs widely in synthetic pyrethroids. Studies have shown significant differences in both aquatic toxicity and degradation rates between enantiomers from the same diastereomer of selected pyrethroids. To better understand chiral selectivity in biodegradation of pyrethroids, 14C-labeled permethrin was used to characterize enantiomeric differences in the formation of transformation intermediates in two soils and a sediment. Individual enantiomers of permethrin were spiked into soil and sediment samples, and transformation products were identified with known standards. Enantioselectivity was observed in most treatments when the dissipation of the parent enantiomers, the amount of intermediates and bound residues formed, and mineralization rates were compared between the enantiomers. The results show that all enantiomers of permethrin hydrolyzed rapidly and that the hydrolysis products were quickly further transformed. The direct hydrolysis products, cyclopropanic acid (Cl2CA), 3-phenoxybenzyl alcohol (PBalc), and 3-phenoxybenzoic acid (PBacid), were recovered at small percentages, ranging from 1 to 14% for Cl2CA and from 0.2 to 6% for PBalc and PBacid. The R-enantiomer of both cis- and trans-permethrin was mineralized more quickly than the S-enantiomer after hydrolysis. The degradation products from cis-permethrin were more persistent than those from trans-permethrin. As some transformation intermediates of permethrin may have greater acute and chronic toxicity than the parent compound, enantioselectivity in the formation of degradation intermediates may lead to different overall toxicities and merit further investigation. This study suggests that for chiral compounds, enantioselectivity may be reflected not only in the dissipation of the parent enantiomers but also in the kinetics of formation of intermediate transformation products.

Biodegradation, Environmental↗

PubMed2000

Feeding and survival of Culicoides sonorensis on cattle treated with permethrin or pirimiphos-methyl.

The persistence of permethrin (5% a.i.) and pirimiphos-methyl (27% a.i.), applied to the dorsum of calves in the field against Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae), was estimated using a hair-blood-feeding bioassay in the laboratory. Hair clippings were taken before treatment and 3, 7, 14, 21, 28, 42 and 56 days after treatment from the dorsum, side and belly of treated and control calves. Laboratory-reared insects were allowed to feed through thin hair layers and a parafilm membrane on sheep blood warmed using a water-jacketed feeder. Some intoxication after exposure to hair was noted up to 28 days after treatment with permethrin and up to 14 days after treatment with pirimiphos-methyl. Hair from the dorsum caused more intoxication for a longer period than hair from other body regions. Permethrin and pirimiphos-methyl applied to the back did not significantly reduce overall engorgement (body regions pooled) after treatment. Permethrin residues on hair remained far higher on the back than other body regions and were related to insect intoxication and reduction in engorgement in the laboratory. Residues on belly hair never exceeded 12p.p.m. and did not result in significantly reduced feeding at any time. Engorged insects that exhibited sublethal intoxication from feeding through permethrin-treated hair did recover and matured numbers of eggs comparable to controls. Field trials using treated and control calves and enclosure nets showed that dorsal applications of 5% permethrin were not effective in reducing engorgement, despite some intoxication. Vacuum samples from a calf showed that C. sonorensis fed primarily on the belly. A 0.2% permethrin application on the belly (250 ml) did result in > 80% reduction of C. sonorensis in the enclosure nets at 3 and 7 days after treatment, but activity had subsided by 10 days after treatment. The utility of insecticidal treatments for suppression of this vector is discussed.

Administration, Topical↗

PubMed2003

Comparative evaluation of carbosulfan- and permethrin-impregnated curtains for preventing house-entry by the malaria vector Anopheles gambiae in Burkina Faso.

Pyrethroid-impregnated bednets and curtains are widely employed to reduce the risk of malaria transmission, but pyrethroid-resistance is becoming more prevalent among malaria vector Anopheles mosquitoes (Diptera: Culicidae). As an alternative treatment for curtains, we assessed carbosulfan (a carbamate insecticide) in comparison with permethrin as the standard pyrethroid, against endophilic female mosquitoes of the Anopheles gambiae Giles complex in a village near Ouagadougou, Burkina Faso. The main criterion evaluated was the impact of curtains (hung inside windows, eaves and doorways) on the number of An. gambiae s.l. females active indoors at night. Light-traps were operated overnight (21.00-06.00 hours beside occupied untreated bednets) to sample mosquitoes in houses fitted with net curtains treated with carbosulfan 0.2 g ai/m2 or permethrin 1 g ai/m2 or untreated, compared with houses without curtains. The treated and untreated curtains significantly reduced the numbers of mosquitoes collected indoors, compared with houses without curtains. Carbosulfan-treated curtains had a highly significantly greater effect than permethrin-treated or untreated curtains, the scale of the difference being estimated as three-fold. However, there was no significant difference between the impact of untreated and permethrin-treated curtains on densities of An. gambiae s.l. trapped indoors. Samples of the An. gambiae complex comprised An. arabiensis Patton and both the S- and M-forms of An. gambiae Giles s.s. Susceptibility tests revealed some resistance to DDT and low frequencies of permethrin-resistance, insufficient to explain the poor performance of permethrin on curtains. Among survivors from the diagnostic dosage of permethrin were some specimens of all three members of the An. gambiae complex, but the kdr resistance mechanism was detected only in the S-form of An. gambiae s.s. Questions arising for further investigation include clarification of resistance mechanisms in, and foraging behaviour of, each member of the An. gambiae complex in this situation and the need to decide whether carbosulfan-treated curtains are acceptably safe for use to reduce risks of malaria transmission.

Animals↗

PubMed1982

The effect of soil temperature on the degradation of cis, trans - permethrin in soil.

The degradation of [carbonyl - 14C] - cis, trans-permethrin was studied in Dubbs fine sandy loam soil incubated at 10, 25, and 40 degrees C from 0 to 64 days. The most rapid degradation of permethrin to [carbonyl - 14C] - cis, trans -3- (2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (DCVA) and ultimately 14CO2 occurred at 25 degrees C. Rapid degradation to DCVA also occurred at 40 degrees C, however, further degradation of DCVA to 14CO2 was reduced. Permethrin degradation to 14CO2 was slowest at 10 degrees C. The degradation rate of trans-permethrin was greater than the cis-permethrin at all temperatures tested. The halflives of cis- and trans-permethrin were 55 and 14 days at 10 degrees C, 12 and 5 days at 25 degrees C, and 27 and 4 days at 40 degrees C, respectively. Compounds identified from treated soil were the original [carbonyl - 14C]-cis, trans-permethrin and the major degradation products cis-, and trans-DCVA.

Biodegradation, Environmental↗

PubMed2005

Pyrethroid insecticides, fenvalerate and permethrin, inhibit progesterone-induced alkaline phosphatase activity in T47D human breast cancer cells.

Pyrethroid insecticides exhibited a weak estrogenic activity by stimulation of MCF-7 cell proliferation and induction of alkaline phosphatase (AlkP) enzyme activity in cultured Ishikawa cells. Previously it was reported that fenvalerate and permethrin significantly inhibited the 17beta-estradiol-induced MCF-7 BUS cell proliferation. Although certain pyrethroid insecticides exert estrogenic or antiestrogenic activities, it is not clear whether pyrethroid insecticides act as progesterone agonists or antagonists. Therefore, the aim of this study was to evaluate the effects of fenvalerate and permethrin on AlkP activity as a progesterone-specific response in T47D cells. In the present study, the stimulation of AlkP activity was concentration dependent with addition of progesterone, and maximum activity was observed at concentration of 1 x 10(-8) M. Both fenvalerate (1 x 10(-6) M) and permethrin (1 x 10(-6) M) did not stimulate the AlkP activity, but progesterone (1 x 10(-8) M)-induced AlkP activity was significantly inhibited at 1 x 10(-6) M concentration of fenvalerate and permethrin, respectively. Progesterone receptor (PR) levels in cytosolic protein of T47D cells were studied to determine the relationship between cellular PR expression and AlkP activity. Similar to AlkP activity, progesterone (1 x 10(-8) M) significantly increased PR protein levels compared to control. However, PR protein levels were not affected in T47D cells cultured with fenvalerate and permethrin alone, whereas fenvalerate and permethrin significantly decreased progesterone-induced PR protein levels. Our data indicate that fenvalerate and permethrin exhibit antiprogestagenic activity in T47D human breast cancer cells.

Alkaline Phosphatase↗

PubMed1998

Contact toxicity of permethrin-impregnated fabric to Hyalomma anatolicum excavatum (Acari: Ixodidae): effects of laundering and exposure and recovery times.

A previous study that documented enhanced host attachment by the camel ticks Hyalomma dromedarii Koch after permethrin exposure prompted a similar investigation of permethrin effects in H. anatolicum excavatum Koch, an Old World hardbacked tick suspected of vectoring human pathogens. Contact toxicity tests were conducted with laboratory-colonized male and female H. a. excavatum of the same age exposed for periods of 5, 10, 30, and 60 min to each of 5 fabric treatments: unwashed/untreated; unwashed and treated; and treated fabric given 1, 2, or 3 laundry cycles of warm-water detergent machine washing, followed by hot-air drying. Fabric was tropical weight 100% cotton military uniform. Treated fabric was impregnated with permethrin at 0.125 mg (AI)/cm2. Contact toxicity was measured immediately after and 24 h after fabric contact as proportion of ticks that attached mouthparts to the skin of a host (rabbit) within a 60-min quest period and time lapse (minutes) between contact with the host and attachment. Attachment response immediately after permethrin contact was exposure time- and wash-dependent in both sexes. Proportion of attaching ticks and times to attachment were comparable in controls and in groups exposed to all permethrin-treated fabrics for 5 or 10 min. Contact periods of 30 and 60 min with 0-wash/treated or 1-wash and treated fabric significantly reduced the frequency of attachment and significantly prolonged mean times to attachment. Compared with low levels of attachment response observed immediately after fabric contact, recovery of attachment response was observed 24 h after exposure in these wash/treatment groups, but inhibition was still evident. Permethrin-induced intoxication was more pronounced in males than females. Mortality 24 h after exposure was only significant among females exposed to 0-wash/treated fabric for 60 min. There was no evidence of permethrin-mediated stimulation of the attachment response in H. a. excavatum.

Animals↗

PubMed2002

Permethrin 5% cream versus metronidazole 0.75% gel for the treatment of papulopustular rosacea. A randomized double-blind placebo-controlled study.

BACKGROUND: Permethrin 5% cream used against human ectoparasites suggests that it may be effective in papulopustular rosacea. METHODS: This study included 63 patients diagnosed as having papulopustular rosacea based on the clinical and histological findings. Patients were randomly assigned into permethrin (n = 23), metronidazole (n = 20) and placebo (n = 20) groups. Scores of erythema, telangiectasia, edema and rhinophyma and the numbers of papules, pustules, inflammatory nodules and Demodex folliculorum were determined. Twenty-three patients were given permethrin 5% cream (Zalvor 5% skin cream, 20 patients metronidazole 0.75% gel (Roza gel and 20 patients placebo cream (Basis cream, in packages looking identical to those of metronidazole and permethrin creams, and were recommended to apply them to their faces twice a day. All patients were also given SPF 20 cream for protection against sunlight. Two months of treatment were planned, and the patients were invited to the clinic for fortnightly controls. Scores of erythema, telangiectasia, edema and rhinophyma and the numbers of papules, pustules, inflammatory nodules and D. folliculorum were recorded at each visit. The mean scores of erythema and the mean numbers of papules, pustules and D. folliculorum were determined at baseline and on days 15, 30, 45 and 60. Side effects were also detected. RESULTS: The effect of permethrin 5% cream on D. folliculorum was superior to that of metronidazole 0.75% gel. The effect of permethrin 5% cream on erythema and papules was found to be more effective than placebo and as effective as metronidazole 0.75% gel. However, it had no effect on telangiectasia, rhinophyma and pustules. CONCLUSION: It can be concluded that the application of permethrin 5% cream twice daily for 2 months can be as effective and reliable as metronidazole in the treatment of rosacea and a greater benefit can be gained when it is combined with other systemic and/or topical treatments.

Administration, Cutaneous↗

PubMed2005

Passive prophylaxis with permethrin-treated tents reduces mosquito bites among North American summer campers.

OBJECTIVE: Over 2 million adolescents participate in summer-camp experiences, placing themselves at risk for mosquito-borne illness. Insect repellent is recommended but often not used. It is unknown whether permethrin treatment of a location, such as a campsite, provides passive prophylaxis reducing mosquito bites among all persons in the immediate vicinity. METHODS: This randomized, double-blind controlled trial used 0.4% permethrin (2.5% permethrin diluted by 7 parts water) sprayed once onto the external surface of canvas tents at a Boy Scout summer camp. During a 9-week period, subjects (n = 545) completed nightly mosquito-bite and -landing counts for 5 minutes at dusk and recorded insect-repellent use within 2 hours of counting. Weekly mosquito sampling with CO2-baited Centers for Disease Control and Prevention traps occurred at study campsites. The primary outcome measure was the number of mosquito bites per 5 minutes. RESULTS: A total of 1614 person nights averaged 5.1 +/- 7.2 (+/- SD) mosquito bites per 5 minutes. The permethrin-treated campsites had decreased mosquito landings and bites (relative risk reduction [RRR] 44%; 95% CI 34% to 55%; P < .001) compared with controls. Insect repellent was used only 32% of nights, decreasing bites by 36% (RRR 36%; 95% CI 25% to 47%; P < .001). Permethrin was superior to insect repellent alone (RRR 20%; 95% CI 4% to 37%; P = .01). CONCLUSIONS: Permethrin treatment of tents is an effective, inexpensive public health measure to reduce mosquito bites. Permethrin is effective among all individuals in a camping setting and was more effective than topical insect repellent alone, which, although recommended, was inconsistently used.

Adolescent↗

PubMed2006

Effect of piperonyl butoxide on permethrin toxicity in the amphipod Hyalella azteca.

Piperonyl butoxide (PBO) is a synergist of pyrethroid pesticides found in many products for structural pest control, mosquito control, and home and garden uses. Because both PBO and pyrethroid residues potentially co-occur in urban creeks, this study determined if environmental levels of PBO were capable of synergizing pyrethroids in the environment. Three types of toxicity tests were conducted with the amphipod Hyalella azteca to determine the minimum PBO concentration required to increase toxicity of the pyrethroid permethrin: Sediment was spiked with permethrin only; permethrin and overlying water spiked with PBO; and permethrin, PBO, and overlying water spiked with PBO. In tests with PBO added to both water and sediment, PBO concentrations of 2.3 microg/L in water and 12.5 microg/kg in sediment reduced the permethrin median lethal concentration (LC50) nearly 50% to 7.3 mg/kg organic carbon (OC). Higher concentrations of PBO increased permethrin toxicity up to sevenfold. In exposures with PBO in water alone, 11.3 microg/L was required to increase permethrin toxicity. Urban creek sediments from California and Tennessee, USA, had PBO concentrations in the low microg/kg range; only one water sample was above the detection limit of 0.05 microg/L. Wetlands in northern California also were sampled after application of pyrethrins and PBO for mosquito abatement. Sediment and water PBO concentrations within 12 h of abatement spraying peaked at 3.27 microg/kg and 0.08 microg/L, respectively. These results suggest that environmental PBO concentrations rarely, if ever, reach concentrations needed to increase pyrethroid toxicity to sensitive organisms, though available data on environmental levels are very limited, and additional data are needed to assess definitively the risk.

Amphipoda↗

PubMed2006

Initial evaluation of N,N-diethyl-m-toluamide and permethrin absorption in human volunteers under stress conditions.

OBJECTIVES: This was a pilot study to determine (1) whether it is feasible to effectively blind human subjects to the presence of the insect repellents N,N-diethyl-m-toluamide (DEET) and permethrin; (2) whether DEET affects the absorption of permethrin; and (3) whether combat videotape viewing and mental arithmetic are stressful. METHODS: Ten volunteers were exposed to DEET, permethrin, and stress (1-hour combat videotape plus mental arithmetic) in a double-blind, randomized, placebo-controlled trial. Outcome measurements included hemodynamics, plasma DEET and permethrin levels, and questionnaires to assess blinding. RESULTS: Highly sensitive serologic assays readily detected DEET but not permethrin. Staff members and subjects were effectively blinded to both. The videotape-math combination was stressful by both self-report and hemodynamic measures. CONCLUSIONS: It is possible to blind subjects with respect to DEET and permethrin. Permethrin on clothing does not enter the bloodstream at appreciable levels. Combat videotapes and mental arithmetic can be stressful.

Adult↗

PubMed1998

[Impact of resistance of Anopheles gambiae s.s. to permethrin and deltamethrin on the efficacy of impregnated mosquito nets].

Trials to assess the impact of resistance of Anopheles gambiae s.s. to permethrin and deltamethrin on the efficacy of insecticide-treated bednets were carried out from October 1997 to April 1998 in six experimental huts at the Yaokoffikro testing station in Côte d'Ivoire. Six polyester bednets were used. Two bednets were treated with permethrin at a dose of 500 mg/m2 and two with deltamethrin at 25 mg/m2. The remaining two untreated bednets served as controls. The number of Anopheles gambiae s.s. entering the hut was reduced 18% with permethrin-treated bednets and 43% with deltamethrin-treated bednets. Threefold fewer female mosquitoes were found under insecticide-treated bednets than under untreated nets (controls). The number of mosquitoes passing through the treated net was threefold lower. The number of mosquitoes exiting from the treated bednets increased twofold. The blood-feeding rate dropped by 55%. Forty percent of mosquitoes entering the permethrin-treated bednets and 56% entering the deltamethrin-treated bednets died. Immediate mortality was always greater (> 85%) than delayed mortality (< 15%). Bioassays confirmed the results from hut experiments. A lower knockdown effect was recorded with permethrin in the resistant strain. Conversely deltamethrin showed the same knockdown effects in the susceptible (Kisumu) and resistant (Yaokoffikro) strain. Mortality rates were low with both permethrin and deltamethrin. This study shows that, even in areas where Anopheles gambiae s.s. is resistant to permethrin and deltamethrin, bednets treated with these insecticides remain effective and can still be considered as an excellent method of personal protection.

Animals↗

PubMed2003

Efficacy of two 65% permethrin spot-on formulations against induced infestations of Ctenocephalides felis (Insecta: Siphonaptera) and Amblyomma americanum (Acari: Ixodidae) on beagles.

The efficacy of two formulations of a topically applied 65% permethrin spot-on (Defend Exspot Treatment for Dogs, Schering-Plough Animal Health) was evaluated against experimental infestations of the cat flea Ctenocephalides felis and the lone star tick Amblyomma americanum in dogs. Eighteen dogs were randomly assigned to treatment with 65% permethrin in either diethylene glycol monomethyl ether (DGME; original formulation) or propylene glycol monomethyl ether (PGME) or to be untreated as a control. Treated dogs received either 1 (body weight < 15 kg) or 2 ml (body weight > or =15 kg) of the assigned formulation on Day 0. One hundred unfed, adult C. felis were placed on each dog on Days -6, -1, 4, 11, 18, 25, and 32. Fifty unfed, adult ticks were placed on each dog on Days -1, 3, 9, 16, 23, and 30. Live fleas and ticks were counted and removed on Days 3, 7, 14, 21, and 28. Treatment of dogs with the 65% permethrin in DGME reduced flea numbers by 90.4% to 99.9% from Days 3 through 21 (P < or =.05) and by 48.2% 28 days after treatment. Treatment of dogs with 65% permethrin in PGME reduced flea numbers by 93.7% to 99.7% from Days 3 through 28 and by 78.4% 35 days after treatment (P < or =.05). Treatment with 65% permethrin in DGME reduced tick numbers by 90% or more only on Day 7, whereas treatment with 65% permethrin in PGME reduced the number of live ticks by 90%or more on Days 7 and 14 and approached 90%(87.9%) on Day 21. Efficacy against fleas and ticks for the PGME formulation was significantly better (P < or =.05) than for the DGME formulation on Day 28. Findings in this study indicate that both the DGME and PGME formulations of 65% permethrin performed well in reducing numbers of live C. felis and A. americanum on laboratory beagles; however, the PGME formulation was effective approximately 1 to 2 weeks longer than the DGME formulation.

Animals↗

PubMed2004

Repellency of permethrin-treated battle-dress uniforms during Operation Tandem Thrust 2001.

Successful feeding by mosquitoes through permethrin-treated battle-dress uniforms (BDUs) was observed in the Shoalwater Bay Training Area (SWBTA), Queensland, Australia, during Operation Tandem Thrust 1997 (TT97). Therefore, during Operation Tandem Thrust 2001, the repellency of permethrin-treated BDUs was evaluated. Washing permethrin-treated BDUs 1 time reduced the permethrin concentration by 60%, but permethrin concentration was not reduced further after subsequent washings (up to 20 times). The probing time of Ochlerotatus vigilax landing on permethrin-treated BDUs was reduced to the greatest extent on the treated, unwashed uniform (7.5-fold reduction). Treated, washed uniforms also reduced probing time (2.5 times) compared to the untreated control uniform containing no permethrin. Reduced probing time should reduce feeding success and protect operational forces from bothersome mosquitoes and the associated risk of mosquito-borne disease in SWBTA. Observations of successful mosquito feeding made during TT97 could be attributed to the use of old and well-worn BDUs and seasonal differences in mosquito population density.

Animals↗

PubMed1996

Comparative percutaneous absorption of lindane and permethrin.

BACKGROUND AND DESIGN: Because of the concern for potential neurotoxic effects (central nervous system excitation, convulsions) in the treatment of scabies using 1% lindane lotion, 5% permethrin cream has been suggested as an alternative scabicide. Using the finite dose technique, in vitro percutaneous absorption of 5% permethrin cream or 1% lindane lotion was measured in human and guinea pig skin following a single application. In vivo blood and brain levels of the scabicides were measured in guinea pigs following three daily applications of 5% permethrin cream or 1% lindane lotion. Permethrin and lindane levels were quantified by gas chromatography/mass spectroscopy. RESULTS: In vitro percutaneous absorption of the two scabicides was identical in guinea pig skin; however, human skin was 20-fold more permeable to lindane than to permethrin. In vivo guinea pig blood and brain levels of lindane were fourfold greater than permethrin levels. CONCLUSION: The risk for toxic effects, as assessed by systemic exposure during overuse conditions, is projected to be 40 to 400 times lower for 5% permethrin cream than for 1% lindane lotion.

Animals↗

PubMed2002

Binding of pyridostigmine bromide, N,N-diethyl-m-toluamide and permethrin, alone and in combinations, to human serum albumin.

In this study we examined the interaction of the anti-nerve agent drug pyridostigmine bromide (PB, 3,3-dimethylaminocarbonyloxy- N-methylpyridiniyum bromide), the insect repellent DEET ( N, N-diethyl- m-toluamide), and the insecticide permethrin [3-(2,2-dichloroethyl)-2,2-dimethylcyclopropanecarboxylic acid (3-phenoxyphenyl)methyl ester] in binding to human serum albumin (HSA). Concentrations between 500 ng/ml and 10 microg/ml PB, DEET and permethrin, alone or in combination, were incubated with HSA at 37 degrees C for 60 min. Concentrations of PB, DEET and permethrin were determined using high performance liquid chromatography (HPLC). The results showed that 81.2+/-4.2%, and 84.6+/-2.5% of the initial concentration of PB was bound to HSA when incubated alone or in combination with DEET or permethrin, respectively. DEET and permethrin did not significantly interact with HSA after 1 h of incubation. Incubation of combinations of two or three compounds did not significantly alter the binding pattern of any of the compounds with HSA. These results showed that PB is highly bound to albumin protein, while the competition between PB, DEET and permethrin on binding sites of HSA as a possible site of interaction following combined administration in vivo is not likely.

Analysis of Variance↗

PubMed1988

Chronic toxicity and carcinogenic evaluation of permethrin in rats and mice.

Groups of Alpk:AP (Wistar-derived) rats were fed diets containing 0, 500, 1000 or 2500 ppm permethrin for 2 years and Swiss-derived mice were maintained for their lifetime (80% mortality) on diets containing 0, 250, 1000, or 2500 ppm permethrin. Changes of toxicological significance were confined to the top dose level of 2500 ppm permethrin in both species. Tremors and hypersensitivity to noise were noted in rats at this dose during the first 2 weeks of study but such signs were not seen in mice. Pathological examination of the central and peripheral nervous systems did not reveal abnormalities attributable to permethrin administration. The effect on mice at 2500 ppm permethrin was shown by decreased body weight gain. Liver hypertrophy, associated with increase in liver weight, microsomal enzyme activity, and proliferation of smooth endoplasmic reticulum occurred in the rat with similar but less marked changes in the mouse. This was considered to be an adaptive response of no toxicological significance. No evidence of a carcinogenic effect was seen in the rat study. In the mouse study a slight elevation in benign lung tumor incidence in males only at 2500 ppm permethrin was observed but was not considered to represent a carcinogenic effect.

Animals↗