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PubMed1989

Study on dermal toxicity and urinary metabolites of the new insect repellent N,N-diethylphenylacetamide in rabbits.

Dermal toxicity of the new multi-insect repellent N,N-diethylphenylacetamide (DEPA) was studied in female rabbits. LD50 of DEPA was estimated to be 3505 mg/kg b.w. On daily topical application for 21 d at a dose of 50 mg/kg b.w., dermal irritancy score and blood chemistry changes indicated that the compound is non-irritant and non-toxic. N-Ethylphenylacetamide and conjugated phenylacetic acid were identified as the urinary metabolites of DEPA by gas-liquid chromatography.

Acetamides↗
PubMedDate not supplied

The conduct of a two-generation reproductive toxicity study via dermal exposure in the Sprague-Dawley rat--a case study with KBR 3023 (a prospective insect repellent).

KBR 3023, 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)-piperidine, a prospective insect repellent being developed by the Bayer Corporation, was evaluated for reproductive toxicity in the Sprague-Dawley rat. As the intended human use of the test compound is topical, the test system was also exposed to the compound via the dermal route. Specifically, the adult rats (P generation) were fitted with Elizabethan collars, to reduce the likelihood of oral ingestion, and dermally administered either 0, 50, 100, or 200 mg KBR 3023/kg body weight throughout the study (5 d/week) beginning at the onset of the 10-week premating period and continuing through the mating, gestation, and lactation phases. Clinical signs and changes in body weight and food consumption were assessed throughout the study. All adults and neonates underwent a gross necropsy examination. Tissues retained for microscopic examination from all adult animals included the kidney, liver, pituitary, reproductive organs, and samples of skin from the shaved dose site. In addition to the parameters noted above, the animals were evaluated for the effect of the test compound on estrous cycling, mating, fertility, gestation length, litter size, pup sex ratio, and pup viability. There were no test compound-related clinical signs or effects on body weight or food consumption observed in either the adults or the pups during any phase of the study. There were no compound-related effects on any reproductive or litter parameters. Dermal findings at the dose site (acanthosis and hyperkeratosis) were noted in both generations. Other than the dermal findings, no compound-related necropsy findings were seen in either the adults or the pups. No compound-related histopathologic findings were noted in the reproductive tissues of either the males or females. Based on these results, KBR 3023, administered as described in this study at dose levels as high as 200 mg/kg body weight (the physical limit of dermal application for this compound), did not demonstrate any reproductive toxicity.

Administration, Topical↗
PubMed1988

Some corrections to the record on insect repellents and attractants.

Fifteen apparent errors of observation, reporting, interpretation, or attribution occurring in the insect repellent and attractant literature were examined. Topics discussed are the boiling point effect, solvents and solutions, repellent-treated netting, terpineol and diphenyl oxide, lactic acid, the smell and feel of deet (diethylmethylbenzamide), effective half-life, protection time, protection time of deet for men and women, McGuire's formula, "plussing out", King's classification, exorbitant doses, extrapolated doses, and extreme observations. The decay constant (1.36 hr-1) and half-life (0.51 hr) of a mosquito-repellent bath oil (Skin-So-Soft) are reported for the first time.

Animals↗
PubMed2001

Laboratory & field evaluation of controlled release formulation of the insect repellents N,N-diethyl-m-toluamide (DEET) & N,N-diethyl phenylacetamide (DEPA) against mosquito vectors.

BACKGROUND & OBJECTIVES: Repellents can play a useful role in reducing the man-vector contact and help in interrupting disease transmission. Newer formulations are necessary to improve the efficacy of the repellent on the treated sites for enhanced protection. METHODS: To determine the comparative efficacy, 20 per cent liposphere lotion formulation and 20 per cent alcohol solution of two insect repellents DEET and DEPA were evaluated for the extent of protection on rabbits against Aedes aegypti during the day in the laboratory and on human volunteers during the night against Culex quinquefasciatus in the urban areas of Pondicherry, India. RESULTS: In the laboratory, the lotion formulations of DEPA and DEET were found to enhance the repellency by 1.5 (4.00 to 6.00 h) and 1.25 (4.00 to 5.00 h) times respectively compared to the alcohol solution of the repellents against Ae. aegypti at the application rate of 0.5 mg/cm2. In the field, the lotion formulation of DEPA at 0.3 mg/cm2 could increase the protection time from 6.30 to 8.36 h (1.3 times) whereas the lotion formulation of DEET at 0.3 mg/cm2 could increase the protection time from 6.54 to 8.42 h (1.2 times). INTERPRETATION & CONCLUSION: In laboratory and field tests, the lotion formulations of both repellents were found to give a higher protection compared to alcohol solution. The lotion formulations of DEET and DEPA were found to be equally effective.

Acetamides↗
PubMed2006

Laboratory evaluation of 21 insect repellents as larvicides and as oviposition deterrents of Aedes albopictus (Diptera: Culicidae).

Twenty-one commercial insect repellent products, including 12 botanical, 6 DEET-based, and 3 synthetic organics, were evaluated as larvicides and as oviposition deterrents of Aedes albopictus. Ten of the 12 botanical products at 0.1% concentration provided 57-100% mortality of laboratory-reared 4th-stage Ae. albopictus larvae at 24 h after treatment. Five of the 6 DEET-based products and 3 synthetic organic repellents at 0.1% concentration induced 88-100% larval mortality at 24 h after treatment. All 12 botanical products proved highly effective oviposition deterrents of Ae. albopictus, resulting in 76-100% effective repellency at 24 h after exposure. The 6 DEET-based repellents and the 3 synthetic organic repellents caused 84-100% effective oviposition repellency of Ae. albopictus at 24 h after exposure. Several botanical repellents previously shown to have minimal protection from mosquito bites proved effective oviposition deterrents. Some commercial topical repellents have good potential for development and use in management of container-inhabiting mosquitoes because they deter oviposition and kill larvae.

Aedes↗
PubMed1993

Insect repellent (N,N-diethyl-m-toluamide) cardiovascular toxicity in an adult.

OBJECTIVE: To describe a case of N,N-diethyl-m-toluamide (DEET)-induced cardiovascular toxicity in an adult and reviews other cases that have been reported in the published literature. Human and animal data available on DEET pharmacokinetics are reviewed and factors that predispose an individual to DEET toxicity are identified. DATA SOURCES: Case report information was obtained through personal contact with the patient during hospitalization and by telephone, and also from the patient's medical records. Computerized literature searches were conducted with the following systems to obtain medical literature on DEET toxicity: TOXLINE, International Pharmaceutical Abstracts, and MEDLINE. Index Medicus was searched manually. STUDY SELECTION: All reported cases of DEET toxicity in children and adults were reviewed. DATA EXTRACTION: Case reports were evaluated for the quantity of the DEET exposure (topical or oral), the clinical manifestations of the exposure, and the outcome of the exposure. DATA SYNTHESIS: This case is similar in some aspects to those already in the literature; however, very few cases of DEET toxicity in adults have been reported. Cardiovascular toxicity in humans related to DEET application has not been previously reported in the published medical literature. DEET exposure (topical or oral) results in a highly variable clinical course. Whether the outcome is death or recovery without sequelae is difficult to predict. CONCLUSIONS: Adults, as well as children, are at risk for toxicity from insect repellents. The use of highly concentrated DEET-containing insect repellents should be avoided to reduce the risk of toxicity in both children and adults. The consequences of DEET toxicity are variable and unpredictable.

Administration, Cutaneous↗
PubMed2001

Laboratory and field evaluation of insect repellents as larvicides against the mosquitoes Aedes albopictus and Anopheles albimanus.

Acute toxicity and persistence of three insect repellents, deet and two piperidines (AI3-35765 and AI3-37220), were evaluated against mosquito larvae of Aedes albopictus (Skuse) and Anopheles albimanus Wiedemann (Diptera: Culicidae) in the laboratory, and against natural populations of Ae. albopictus in the field. In laboratory studies, the LC50 values of the repellents for first instars ranged between 0.005 and 0.021% (Ae. albopictus) and between 0.01 and 0.014% (An. albimanus) and, for fourth instars, between 0.019 and 0.034% (Ae. albopictus) and between 0.015 and 0.024% (An. albimanus). A 0.1% concentration of deet caused 90-100% mortality in first-instar Ae. albopictus for 4 weeks, whereas AI3-35765 and AI3-37220 at the same concentration killed 95-100% of larvae for 12 weeks and 98-100% of larvae for 33 weeks post-treatment, respectively. Deet and AI3-35765 at 0.1 % concentration resulted in complete mortality of first-instar An. albimanus for 3 weeks post-treatment, whereas AI3-37220 resulted in 91-99% larval mortalities for 35 weeks post-treatment. A 0.1% concentration of A13-37220 provided 77-98% larval mortality for 20 weeks and 63-97% larval mortality for 12 weeks post-treatment, respectively, against fourth-instar Ae. albopictus and An. albimanus. In the field, in artificial containers, the reduction of Ae. albopictus larvae caused by deet, AI3-35765 and AI3-37220 was 88-95% for 3-4 weeks, 98-100% for 7 weeks, and 82-100% for 13 weeks post-treatment, respectively. In used tyres, the same concentration of the repellents resulted in 100% reduction of Ae. albopictus larvae for 2 weeks (deet), 4 weeks (AI3-35765) and 5 weeks (AI3-37220) post-treatment. In cemetery flower vases, Aedes spp. larvae were eliminated for 4 weeks (deet) and 6 weeks post-treatment by both A13-35765 and AI3-37220. These topical repellents (particularly AI3-37220) have good potential for development and use in the management of container-inhabiting mosquitoes because they deter oviposition and kill larvae.

Aedes↗
PubMed2005

Analysis of molecular stereoelectronic similarity between N,N-diethyl-m-toluamide (DEET) analogs and insect juvenile hormone to develop a model pharmacophore for insect repellent activity.

Similarity analysis on molecular stereoelectronic properties of N,N-diethyl-m-toluamide (DEET), natural insect juvenile hormone (JH), a synthetic insect juvenile hormone mimic (JH-mimic, undecen-2-yl carbamate), and DEET compounds reveals remarkable similarities that lead to a reliable pharmacophore for the design of efficacious insect repellents and provide insights for understanding the mechanism of repellent action. The study involves an AM1 quantum chemical computational procedure enabling a conformational search for the lowest and most abundant energy conformers of JH, JH-mimic, and 15 DEET compounds and complete geometry optimization of the conformers. Similarity analyses of stereoelectronic properties such as structural parameters, atomic charges, dipole moments, molecular electrostatic potentials, and highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies were performed on JH, JH-mimic, and the DEET compounds. Similarity of stereoelectronic attributes of the amide/ester moiety, negative electrostatic potential regions beyond the molecular surface, and a large distribution of hydrophobic regions in the compounds appears to be the 3 important factors leading to a similar interaction with the JH receptor. The similarity of electrostatic profiles beyond the molecular surface is likely to play a crucial role toward molecular recognition interaction with the JH receptor from a distance which suggests a possible electrostatic bioisosterism of the amide group of the DEET compounds and JH-mimic and, thus, a model for molecular recognition at the JH receptor.

Aedes↗
PubMed1993

Diethylphenylacetamide: a new insect repellent against stable fly, Stomoxys calcitrans.

This paper reports the results of a laboratory study showing effectiveness of a new insect repellent N,N-diethylphenylacetamide (DEPA) against stable fly, Stomoxys calcitrans, and compared to N,N-diethyl-m-toluamide (DEET) and dimethyl-phthalate (DMP). DEPA gave maximum protection time of more than 6 h at 3% concentration followed by DEET and DMP.

Acetamides↗
PubMed2001

Laboratory and field evaluation of insect repellents as oviposition deterrents against the mosquito Aedes albopictus.

Three experimental approaches were used to evaluate the oviposition deterrency of three insect repellents, AI3-35765, AI3-37220 (piperidine compounds), and the standard N,N-diethyl-3-methylbenzamide (deet) to the mosquito Aedes albopictus Skuse (Diptera: Culicidae). Against laboratory-reared Ae. albopictus gravid females, the EC50 values of AI3-37220, AI3-35765 and deet were 0.004%, 0.008% and 0.011% in laboratory cages and 0.004%, 0.01% and 0.009% in an outdoor screened cage. For a natural population of Ae. albopictus tested in the field, the EC50 values were determined as 0.004%, 0.008% and 0.001%, respectively. Ageing concentrations of 0.1% of each repellent provided >50% effective oviposition deterrency against the laboratory population of Ae. albopictus for 13 days in laboratory cages, for 15 days in the outdoor cage, and for 21 days against field population of Ae. albopictus in Florida. These topical skin repellents are effective oviposition deterrents for Ae. albopictus when employed at relatively low application rates.

Aedes↗
PubMed1982

Dermal penetration and potential for placental transfer of the insect repellent, N,N-diethyl-m-toluamide.

N,N-Diethyl-m-toluamide (m-Det) is a widely used insect repellent readily available in various formulations. Radiolabeled (14C) m-Det was evaluated for rate and extent of skin penetration in three animal species. Absorption was quantitated in excreta for 7 days following a single dermal application and deposition monitored in tissues at necropsy. The potential for transplacental transfer and bioaccumulation of absorbed m-Det the fetus was also assessed following repeated applications to pregnant rabbits. Significant dermal absorption of the repellent was noted in all species, primarily in the first few hours, and was essentially complete after 3 days. No bioaccumulation of the labeled moiety was noted in tissues at 7 days. Pregnant rabbits receiving repeated dermal applications throughout gestation showed no evidence of bioaccumulation of the chemical in maternal tissue or individual fetuses. It is suggested that m-Det should not present a dermatoxic hazard to man and that topical absorption should be less than 10% of the applied dose.

Absorption↗
PubMed1991

Distribution and metabolism of insect repellant N,N-diethylphenylacetamide on oral exposure in rats.

Oral toxicity, distribution and metabolism of a new multi-insect repellant, N,N-diethylphenylacetamide (DEPA) was studied in rats. On administration of DEPA (851 mg/kg body wt.) labelled with 14C blood, liver, stomach and stomach contents had 2.65, 3.97, 12.07 and greater than 50.66% radioactivity, respectively, after 20 min. Gas chromatographic analysis showed presence of both DEPA and its metabolite N-ethylphenylacetamide (EPA) in blood, liver, kidneys and lungs while only DEPA was present in stomach and stomach contents. EPA, phenylacetamide and conjugated phenylacetic acid were excreted along with unmetabolized parent compound in urine of rats when a low oral dose of DEPA (70 mg/kg body wt.) was administered. Activities of erythrocyte cholinesterase and carbonic anhydrase did not change significantly upon acute oral exposure to DEPA.

Acetamides↗
PubMed1997

Pharmacokinetics of insect repellent N,N-diethyl-m-toluamide in beagle dogs following intravenous and topical routes of administration.

The common topical insect repellent N,N-diethyl-m-toluamide (DEET) has caused serious adverse effects in the users of DEET products due to its high skin permeability. This study investigated the pharmacokinetics of DEET following i.v. and dermal routes of administration in beagle dogs. The pharmacokinetics of DEET was linear over the dose range of 2.5-6.0 mg/kg. Following the i.v. dosing, plasma DEET concentrations declined biexponentially with an elimination half-life of 2.56 h. Volume of distribution at steady-state, systematic clearance, and mean residence time were estimated as 6.21 L/kg, 2.66 L/h/kg, and 2.34 h, respectively, indicating that DEET underwent extensive extravascular distribution and rapid elimination. After the dermal application of a commercial lotion and a new DEET lotion at 15 mg of DEET/kg, plasma DEET concentrations peaked at 1-2 h postdose. The DEET transdermal bioavailability and mean absorption time were 18.3% and 2.05 h, respectively, for the commercial lotion and 14.0% and 2.66 h, respectively, for the new lotion. The difference in DEET transdermal absorption between the two lotions suggested that commercial DEET products could be optimized for reduced DEET absorption for safer use.

Administration, Cutaneous↗
PubMed1998

Short report: The safety and toxicity of insect repellents.

In recent years, concerns have been raised regarding the safety of diethyltoluamide (DEET), one of the most widely used and reliable insect repellents available. This paper summarizes the recent evidence and concludes that concerns over safety appear largely unfounded.

Animals↗
PubMed1991

Insect repellent N,N-diethylphenylacetamide: an update.

N,N-diethylphenylacetamide (DEPA) has repellent activity against hematophagous insects including mosquitoes, black flies, horse flies, muscoid flies, rat fleas, and ticks, as well as land leeches and cockroaches. The efficacy of DEPA is comparable to that of N,N-diethyl-3-methylbenzamide (DEET) in both laboratory and field tests. Toxicological studies indicate that DEPA is safe for human use. Different formulations as well as fabrics impregnated with DEPA are effective for personal protection from insect bites.

Acetamides↗
PubMed1993

Acute oral toxicity of insect repellent N,N-diethylphenylacetamide in mice, rats and rabbits and protective effect of sodium pentobarbital.

Median lethal dose (LD50) of undiluted liquid insect repellent N,N-diethylphenylacetamide (DEPA) in male mice, rats and rabbits was 900, 825 and 635 mg/kg respectively when administered by gavage. Signs of DEPA intoxication point to stimulation of central nervous system (CNS). Acetazolamide (10 mg/kg), sodium bicarbonate (40 mg/kg), and atropine (5 mg/kg) when injected (ip) 5 min after a lethal oral dose of DEPA (1700 mg/kg) did not prevent mortality, while sodium pentobarbital (SPB; 20 mg/kg) when injected 5 min after or 15 min before DEPA provided greater protection to the animals. SPB pretreatment elevated the LD50 of DEPA to 1780 and 1535 mg/kg in mice and rats respectively and 85% rats survived when SPB was injected 5 min after acute oral exposure to DEPA (1000 mg/kg). Carboxylesterase (CaE) inhibition is not a factor in the protection mechanism of SPB. DEPA (1000 mg/kg) when given orally elevated blood PCO2 and reduced pH, O2 content and per cent O2 saturation, while administration of SPB after the same dose of DEPA reduced the degree of acidosis and raised PCO2, and increased the O2 content and per cent O2 saturation to near normal status. The CNS depressant action of SPB may be a crucial factor in protection of rats from DEPA poisoning.

Acetamides↗
PubMed2000

Conduct and interpretation of a dermal developmental toxicity study with KBR 3023 (a prospective insect repellent) in the Sprague-Dawley rat and Himalayan rabbit.

KBR 3023, 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)piperidine, a prospective insect repellent being developed by Bayer Corporation, was evaluated for developmental toxicity in the Sprague-Dawley rat and Himalayan rabbit. As the intended human usage of the test compound is topical, the test systems were exposed to the compound via the dermal route. Specifically, the animals were fitted with Elizabethan collars, to reduce the likelihood of oral ingestion, and dermally administered either 0, 50, 200, or 400 mg KBR 3023/kg (rat), and 0, 50, 100, or 200 mg KBR 3023/kg (rabbit) on gestation days 0-19 (rat) and 0-28 (rabbit). Maternal toxicity, as demonstrated by clinical signs and changes in body weight gain and food consumption during gestation, was characterized. Animals were sacrificed on gestation day 20 (rat) and 29 (rabbit), at which time fetuses were removed by cesarean section and a gross maternal necropsy was performed. All fetuses were evaluated for external anomalies. With rats, approximately half of each litter was examined for visceral effects; the other half underwent a skeletal examination. With rabbits, all fetuses underwent both visceral and skeletal examinations. No effects were observed on maternal body weight gain or food consumption in either the rat or rabbit. In the rat, dermal effects (scaling/sloughing), were observed at the dose site of all test substance-treated groups from approximately gestation day 7 until termination of the study. Also noted were an increase in both absolute and relative liver weights in rats in the 400-mg/kg dose group. In the rabbit, dermal effects (slight erythema, squamous and cracked skin) were noted at the dose site of virtually all does administered the test compound, from approximately gestation day 7 until termination. Also observed in the rabbits was a potentially compound-related increase in soft stool, particularly at the highest dose level. In both species, there were no statistically significant effects on any reproductive parameters, or any embryonic endpoints, including pre/post-implantation loss and resorptions. There were no statistically significant effects on litter size or fetal or placental weights. No test compound-related external, visceral, or skeletal findings were observed. No effect on the individual fetal or litter incidence of total malformations or variations was observed and there was no difference in the incidence of malformations between males and females. KBR 3023 Technical, administered as described in these studies, produced maternal effects in the rat (liver weight) at a dose of 400 mg/kg, and in the rabbit (soft stool) in the 200-mg/kg dose group. No developmental toxicity was observed at any dose level.

Administration, Cutaneous↗