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Monographs of Topical Drugs that Have Caused Contact Allergy/Allergic Contact Dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
A 56-year-old woman with chronic eczema on the dorsum of the right foot associated with venous insufficiency developed eczematous lesions on sun-exposed areas (face, neck, nape, forearms, dorsum of the hands) progressing within 2 months to erythroderma, exacerbated on sun-exposed areas. She did not take any oral drugs. The patient was a farmer and handled the insecticide deltamethrin. Photopatch tests showed photocontact allergy to chlorpromazine with UVA at D2 and D3, but were negative to deltamethrin. The patient was informed by her chemist about the various topical drugs containing a phenothiazine and recognized the pharmaceutical gel containing 0.75% isothipendyl that she applied on her foot to reduce the pruritus. Next, a photopatch test with the gel was strongly positive (D1 ++, D2 +++) but was negative in the unirradiated patch test. After stopping use of the gel, the lesions disappeared within 1 month with symptomatic treatment and with strict external photoprotection (2).
Rationale and technique of malaria control
Published in David A Warrell, Herbert M Gilles, Essential Malariology, 2017
David A Warrell, Herbert M Gilles
During the last 10 years, several field trials have demonstrated that the protective effect of mosquito nets can be greatly enhanced by treating them with a repellent or insecticide. The insecticides that are most commonly used for mosquito-net impregnation are the pyrethroids, especially permethrin (0.2–0.5 g a.i.a/m2), deltamethrin (15–25 mg a.i./m2) and lamdacyhalothrin (20–30 mg a.i./m2), because of their low toxic hazard and good residual effect. Others are being tested and some may prove to be good alternatives. Good results have also been reported using curtains on doors and windows and eaves strips impregnated with permethrin (1.0 g a.i./m2). Good reviews of this type of approach are given by Curtis et al. (1990), Rozendaal (1989) and WHO (1989).
Carboxylesterase Inhibitors: Relevance for Pharmaceutical Applications
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Besides the above-mentioned compounds, other compounds, including fatty acids, sterols, pyrethroids, and therapeutic drugs, also displayed strong inhibitory effects against carboxylesterase (Xu et al., 2016; Lei et al., 2017; Wang et al., 2017). Crow et al. found that most naturally occurring fatty acids strongly inhibited the hydrolytic activities of recombinant CES1, with the IC50 values at micromolar range Crow et al. (2010). Unsaturated fatty acids displayed potent inhibitory effects on CES1 than saturated ones, while they also display high specificity towards CES1 over CES2. 27-Hydroxycholesterol (27-HC), an oxidized form of cholesterol, also showed promising inhibitory activity against recombinant CES1 (IC50 46 nM) and high selectivity over CES2. 27-HC functioned as noncompetitive inhibitor against CES1, with the very low Ki value (10 nM) (Crow et al., 2010). Bakuchiol, a natural phenolic compound isolated from Fructus Psoraleae (Bu-gu-zhi in Chinese), strongly inhibited CES2 (Li et al., 2015). Pyrethroids are a class of organic compounds similar to the natural pyrethrins produced by the flowers of pyrethrums (Chrysanthemum cinerariaefolium). Pyrethroids are popular household insecticides for their relatively low toxicity to mammals in contrast to organophosphorus insecticides. Recently, Ge et al. found that six commonly used pyrethroids including deltamethrin showed moderate inhibitory effects against both CES1 and CES2 (Table 9.9) (Lei et al., 2017). Deltamethrin strongly inhibited CES1-mediated DME hydrolysis in HLM, with the IC50 value of 2.39 μM. Deltamethrin was a competitive inhibitor against CES1-mediated BMBT hydrolysis, but it functioned as a noncompetitive inhibitor against CES1-mediated DME or DMCB hydrolysis in HLM. Further investigations on inhibition kinetic analyses and docking simulations suggested that CES1 had at least two ligand-binding sites, and deltamethrin (DMT) could bind with the same ligand binding site as BMBT. Physostigmine, a natural alkaloid, was a highly specific CES2 inhibitor with the Ki value of 0.358 μM (Umehara et al., 2016). Physostigmine potently inhibited the hydrolysis of irinotecan but did not affect the hydrolysis of clopidogrel in human liver S9. By the catalytic asymmetric [3+2] cyclization of novel 4-isothiocyanato pyrazolones and isatin-derived ketimines, Wang and Zou et al. systhsized a wide range of intriguing dispirotriheterocyclic products in high yield with excellent diastereoselectivity and enantioselectivity (Bao et al., 2018). In addition, a chiral sulfoxide derivative (tert-butyl (3R,4′R)-1-benzyl-2′-((S)-methylsulfinyl)-2,5″-dioxo-1″-phenyl-3″-(p-tolyl)-1″,5″-dihydro-1′H-dispiro[indoline-3,5′-imidazole-4′, 4″-pyrazole]-1′-carboxylate) of this dispirocyclic product was identified to be a promising CES1 inhibitor. The IC50 of this chiral sulfoxide derivative was 0.39 μM, which activity was 20-fold stronger than its enantiomer.
Clinical presentation of type 1 and type 2 pyrethroid poisoning in humans
Published in Clinical Toxicology, 2022
Manna Sera Jacob, Ramya Iyyadurai, Arun Jose, Jude Joseph Fleming, Grace Rebekah, Anand Zachariah, Samuel George Hansdak, Reginald Alex, Vignesh Kumar Chandiraseharan, Audrin Lenin, John Victor Peter
Severe toxic manifestations presenting with seizures or respiratory failure were infrequent in our setting; only 2 patients required intubation for low sensorium/respiratory failure and 3 patients had seizures. Severe cypermethrin and deltamethrin poisoning with seizures, respiratory failure and cardiac toxicity have been described [12–14]; however, our study had predominantly mild to moderate toxicity with these compounds. Of note, none of the patients with cypermethrin poisoning in this study manifested seizures. This contrasts a previous study that compared pyrethroid (cypermethrin) poisoning with organophosphorus-pyrethroid (chlorpyrifos-cypermethrin) combinations [15], wherein, of the 32 patients admitted with cypermethrin poisoning, 6% presented with seizures and 5% needed ventilation. However consonant with the current study, there was no mortality among patients with pure cypermethrin poisoning. In the same study [15], the mortality with chlorpyrifos-cypermethrin poisoning was 13%, strengthening the argument to ban the more toxic combinations in favour of safer pesticides such as pyrethroids. The fatal complications noted in another study from Korea were respiratory failure, severe acidosis, hypotension and renal failure and attributed to cypermethrin, lambda-cyhalothrin and deltamethrin [16]. The relatively higher severity and mortality in these studies could also be explained by solvents such as hydrocarbons than the pyrethroid compound per se, as implicated in the deltamethrin case report [14].
Neurophysiological responses in the brain tissues of rainbow trout (Oncorhynchus mykiss) treated with bio-pesticide
Published in Drug and Chemical Toxicology, 2019
Gonca Alak, Arzu Ucar, Aslı Çilingir Yeltekin, Veysel Parlak, Gizem Nardemir, Merve Kızılkaya, İsmail Hakkı Taş, Mustafa Yılgın, Muhammed Atamanalp, Ahmet Topal, Esat Mahmut Kocaman, Telat Yanık
Finally, an up-regulation in the CYP1A gene was found to be statistically important in deltamethrin/bio-pesticide exposure. In fish, cytochrome P450 has an important role in metabolizing many pollutants. Deltamethrin exposure significantly induced CYP1A gene expression in a time-dependent manner in rainbow trout. The application of a sub-lethal concentration of deltamethrin showed faster toxic metabolism of the pesticide compared to the other groups (Guardiola et al.2014). CYP1A induction was found to be related to the potential to indicate neurological toxicity, which in turn was found to be associated with the amounts of the pesticide or its brain-accumulated metabolites (Johri et al.2006). It was known that several pyrethroids such as DLM have been described as enhancing CYP1A activity (Johri et al.2006, Cárcamo et al.2017, Alak et al.2017b).
Effect of deltamethrin and fluoride co-exposure on the brain antioxidant status and cholinesterase activity in Wistar rats
Published in Drug and Chemical Toxicology, 2018
Adil Mehraj Khan, Rajinder Raina, Nitin Dubey, Pawan Kumar Verma
Deltamethrin, a type II pyrethroid, is extensively used as an ectoparasiticide on animals and as an insecticide in agriculture and public health programs. Pyrethroid exposure has been reported to generate reactive oxygen species and the consequent oxidative stress in various tissues (Dubey et al.2012, 2013, Dar et al.2015, Fetoui et al.2015). Fluoride (F−) is an essential trace element within recommended levels. World Health Organization recommends a guideline maximum F− value of 1.5 mg/L as a level of minimal fluorosis (Dubey et al.2013). In the endemic fluorosis areas of Central Asia and India, water may contain F− levels up to 20 mg/L (Merian et al.2004). F− can cross cell membranes and affect various soft tissues leading to impairment of tissue functions (Kant et al.2010). Oxidative stress has been speculated to play an important role in the toxic effects of F− (Zabulyte et al.2007, Khan et al.2013a).