Lab-made CO2 laser-engraved electrochemical sensors for ivermectin determination.

The ivermectin (IVM), as a broad-spectrum antiparasitic drug, was widely prescribed to treat COVID-19 during the pandemic, despite lacking proven efficacy in combating this disease. Therefore, it is important to establish affordable devices in laboratories with minimal infrastructure. The laser engraving technology has been revolutionary in sensor manufacturing, primarily attributed to the diversity of substrates that can be employed and the freedom it provides in creating sensor models. In this work, electrochemical sensors based on graphene were developed using the laser engraving technology for IVM sensing. Through, the studies that used the techniques of cyclic voltammetry and differential pulse voltammetry, following parameter optimization, for the laser-induced graphene electrode demonstrated a mass transport governed by adsorption of the species and exhibited a linear working range of 10-100 (µmol L-1), a limit of detection (LOD) of 1.6 × 10-6 (mol L-1), a limit of quantification (LOQ) of 4.8 × 10-6 (mol L-1), and a sensitivity of 0.139 (µA µmol L-1). The developed method was successfully applied to direct analysis of pharmaceutical tablets, tap water (recovery of 94%) and synthetic urine samples (recovery between 97% and 113%). These results demonstrate the feasibility of the method for routine analyses involving environmental samples.

Season-Long Simplification of Insect Communities in Dung From Cattle Treated With an Extended-Release Formulation of the Parasiticide Eprinomectin.

Cattle treated with LongRange®, an injectable formulation of the parasiticide eprinomectin, fecally excrete insecticidal residues for an extended period post application. We examined the nontarget effect of these residues by comparing insect communities developing in dung of untreated cattle (week 0) with those developing in dung of cattle treated 1, 2, 4, 8, 12, 16, 20, and 24 or 25 weeks previously. Chemical analyses of dung showed that eprinomectin concentrations peaked at 1 week post application and were still detectable at 25 weeks. Results from two separate experiments showed that dung of untreated cattle supported more total insects (beetles, flies, parasitoid wasps) and insect species than did dung of cattle treated for ≤12 weeks (Experiment 1) and ≤25 weeks (Experiment 2) previously. For the two experiments, an effect of residue on individual taxa was either not detected (nine cases) or was determined to suppress insect development in dung of cattle treated for 8-12 weeks (two cases), 12-16 weeks (three cases), 16-20 weeks (two cases), or 24 or 25 weeks (six cases) previously. Flies and their parasitoid wasps were particularly sensitive to residues with suppression often at or near 100%. These results show that cattle treated with LongRange in spring will fecally excrete residues for the entire grazing season with an associated simplification of the dung insect community. The effect of this simplification on the long-term health on dung-breeding populations of insects on pastures and dung degradation was not examined in the present study, but merits future research. Environ Toxicol Chem 2023;42:684-697. © 2023 His Majesty the King in Right of Canada. Environmental Toxicology and Chemistry © 2023 SETAC. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Anthelmintic resistance in Creole horses in the South of Rio Grande do Sul, Brazil / [Resistência anti-helmíntica em equinos da raça Crioula no sul do Rio Grande do Sul, Brasil]

The objective of the study was to evaluate the antiparasitic resistance against horse nematodes in the South of Rio Grande do Sul, Brazil. The results concerning the tests of anthelmintic efficacy on horses, stored in the database of the Parasitic Diseases Study Group (GEEP) - Veterinary Faculty, at the Federal University of Pelotas (UFPel), were carried out in the laboratory from 2018 to 2019. Stool samples were received from farms with breeding of adult female and male Criollo horses naturally infected, located in municipalities in the country's southern region. The antiparasitic agents tested were Triclorfon + Fenbendazole, Closantel + Albendazole, Ivermectin + Praziquantel, Fenbendazole, Ivermectin, Doramectin, Mebendazole and Moxidectin. Techniques such as Gordon and Whitlock, Coproculture and Fecal Egg Count Reduction Test were performed. Of all the antiparasitic drugs tested, it was observed that only treatments with Ivermectin 2% showed desired values. The observed results indicate that resistance to macrocyclic lactones is usual in equine parasites in this Brazilian region, despite the results with isolated Ivermectin.(AU)

O objetivo deste estudo é avaliar a resistência antiparasitária contra nematodeos de equinos no sul do Rio Grande do Sul, Brasil. Os resultados referentes aos testes de eficácia anti-helmíntica em cavalos, armazenados no banco de dados do Grupo de Estudos de Doenças Parasitárias (GEEP) - Faculdade de Veterinária, da Universidade Federal de Pelotas (UFPel), foram realizados em laboratório, no período de 2018 a 2019. Amostras de fezes foram recebidas de fazendas com criação de cavalos Crioulos adultos fêmeas e machos naturalmente infectados, localizadas em municípios da região Sul do país. Os agentes antiparasitários testados foram triclorfon + fenbendazol, closantel + ivermectina + praziquantel, fenbendazol, ivermectina, doramectina, mebendazol e moxidectina. Técnicas como Gordon e Whitlock, coprocultura e teste de redução da contagem de ovos fecais foram realizadas. De todos os antiparasitários testados, observou-se que apenas os tratamentos com ivermectina 2% apresentaram os valores desejados. Os resultados indicam que a resistência às lactonas macrocíclicas é comum em parasitas equinos nessa região brasileira, apesar dos resultados com ivermectina isolada.(AU)

Determination of Anthelmintic and Antiprotozoal Drug Residues in Fish Using Liquid Chromatography-Tandem Mass Spectrometry.

The objective of this study is to develop a comprehensive and simple method for the simultaneous determination of anthelmintic and antiprotozoal drug residues in fish. For sample preparation, we used the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method with a simple modification. The sample was extracted with water and 1% formic acid in acetonitrile/methanol (MeCN/MeOH) (95:5, v/v), followed by phase separation (salting out) with MgSO4 and NaCl (4:1, w/w). After centrifugation, an aliquot of the extract was purified by dispersive solid-phase extraction (d-SPE) prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The method was validated at three concentration levels for all matrices, in accordance with the Codex guidelines (CAC/GL-71). Quantitative analysis was performed using the method of matrix-matched calibration. The recoveries were between 60.6% and 119.9%, with coefficients of variation (CV) <30% for all matrices. The limit of quantitation (LOQ) of the method ranged from 0.02 µg kg-1 to 4.8 µg kg-1 for all matrices. This comprehensive method can be used for the investigation of both anthelmintic and antiprotozoal drugs belonging to different chemical families in fishery products.

Tissue residues and withdrawal time of moxidectin treatment of swine by topical pour-on application.

Moxidectin (MXD), an antiparasitic drug, is effective for a variety of external and internal parasites in companion and farm animals. This study aimed to calculate the withdrawal period by investigating the residue depletion of MXD in swine edible tissues after pouring at the dosage of 2.5 mg/kg B.W. The concentrations of MXD in swine edible tissues were determined by a modified preparation procedure based on HPLC-FLD. The method was validated giving LOD and LOQ of 0.5 µg/kg and 1 µg/kg respectively with measured recoveries ranging from 62.9%-89.2% at three different concentrations and a precision (RSD) of less or equal to 15.7%. The muscle, liver, kidney and fat tissues were collected at 0.5, 5, 10, 20, 25 d after administration. The results showed that fat was the target tissue with the highest concentration for MXD. The withdrawal period was 26 days for the MRL of 500 µg/kg in fat. The results provide fundamental information to ensure food safety and establishment of a rational medication regimen.

High-resolution AP-SMALDI MSI as a tool for drug imaging in Schistosoma mansoni.

Schistosoma mansoni is a parasitic flatworm causing schistosomiasis, an infectious disease affecting several hundred million people worldwide. Schistosomes live dioeciously, and upon pairing with the male, the female starts massive egg production, which causes pathology. Praziquantel (PZQ) is the only drug used, but it has an inherent risk of resistance development. Therefore, alternatives are needed. In the context of drug repurposing, the cancer drug imatinib was tested, showing high efficacy against S. mansoni in vitro. Besides the gonads, imatinib mainly affected the integrity of the intestine in males and females. In this study, we investigated the potential uptake and distribution of imatinib in adult schistosomes including its distribution kinetics. To this end, we applied for the first time atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) for drug imaging in paired S. mansoni. Our results indicate that imatinib was present in the esophagus and intestine of the male as early as 20 min after in vitro exposure, suggesting an oral uptake route. After one hour, the drug was also found inside the paired female. The detection of the main metabolite, N-desmethyl imatinib, indicated metabolization of the drug. Additionally, a marker signal for the female ovary was successfully applied to facilitate further conclusions regarding organ tropism of imatinib. Our results demonstrate that AP-SMALDI MSI is a useful method to study the uptake, tissue distribution, and metabolization of imatinib in S. mansoni. The results suggest using AP-SMALDI MSI also for investigating other antiparasitic compounds and their metabolites in schistosomes and other parasites.

The effects of heat applications on macrocyclic lactone-structured antiparasitic drug residues in cows' milk.

The study aimed to evaluate the effects of heat on macrocyclic lactone residues in cows' milk. Ivermectin, abamectin, doramectin, eprinomectin and moxidectin were added to raw milk in three concentrations. The milk was then pasteurised (40 seconds at 74°C or 1 minute at 80°C) and boiled (10 minutes at 100°C). The analyses were performed with a validated method: LC-MS/MS. Thermal treatment resulted in a statistically significant decrease in the abamectin, eprinomectin, and moxidectin concentrations in the milk; however, the residues did not completely degrade. Boiling resulted in a greater decrease in the moxidectin concentrations than was observed with pasteurisation. The high pasteurisation and boiling processes had a greater effect on the eprinomectin residues than did the low pasteurisation process. The pasteurisation and boiling processes did not have an effect on the doramectin and ivermectin. The study concluded that the macrocyclic lactones are generally resistant to such processes.

Toxicological effect of ivermectin on the survival, reproduction, and feeding activity of four species of dung beetles (Coleoptera: Scarabaeidae and Geotrupidae) in Japan.

We investigated the effects of the antiparasitic drug ivermectin on the dung beetles Copris acutidens Motschulsky, Onthophagus bivertex Heyden, O. lenzii Harold and Phelotrupes auratus auratus Motschulsky in Japan. Ivermectin was detected in cattle dung from 1 to 3 or 7 days post-treatment, with a peak at 3 days post-treatment in two pour-on administrations (500 µg kg-1). In C. acutidens, adult survivals and numbers of brood balls were significantly reduced in dung collected at 3 and 7 days post-treatment, and adult emergence rates were significantly decreased in dung collected at 7 and 14 days post-treatment. Feeding activity of C. acutidens was inhibited in dung collected at 3 days post-treatment, but was not significantly different from that seen in control dung at 7 and 14 days post-treatment. In O. bivertex and O. lenzii, there were no effects of ivermectin on adult survival or feeding activities, but the numbers of brood balls of O. bivertex constructed in dung collected at 3 and 7 days post-treatment were significantly lower than observed with control dung. The adult emergence rates of O. bivertex and O. lenzii were significantly reduced in dung collected at 1 to 3 and 1 to 7 days post-treatment, respectively. In P. auratus, there were no effects of ivermectin on adult survival, oviposition, feeding activity, or larval survival (until the third instar) in dung at 3 days post-treatment. The environmental risks affecting the populations of dung beetles in Japan are discussed.

Comparison of the Utility of RP-TLC Technique and Different Computational Methods to Assess the Lipophilicity of Selected Antiparasitic, Antihypertensive, and Anti-inflammatory Drugs.

The aim of this study was to assess the lipophilicity of selected antiparasitic, antihypertensive and non-steroidal anti-inflammatory drugs (NSAIDs) by means of reversed phase-thin layer chromatography (RP-TLC) as well by using Soczewinski-Wachtmeister's and J. Oscik's equations. The lipophilicity parameters of all examined compounds obtained under various chromatographic systems (i.e., methanol-water and acetone-water, respectively) and those determined on the basis of Soczewinski-Wachtmeister's and Oscik's equations (i.e., RMWS and RMWO) were compared with the theoretical ones (e.g., AlogPs, AClogP, milogP, AlogP, MlogP, XlogP2, XlogP3) and the experimental value of the partition coefficient (logPexp). It was found that the RMWS parameter may be a good alternative tool in describing the lipophilic nature of biologically active compounds with a high and low lipophilicity (i.e., antihypertensive and antiparasitic drugs). Meanwhile, the RMWO was more suitable for compounds with a medium lipophilicity (i.e., non-steroidal anti-inflammatory drugs). The chromatographic parameter 0(a) can be helpful for the prediction of partition coefficients, i.e., AClogP, XlogP3, as well as logPexp of examined compounds.

Aerobic dissipation of avermectins and moxidectin in subtropical soils and dissipation of abamectin in a field study.

Avermectins and moxidectin are antiparasitics widely used as active pharmaceutical ingredients in veterinary medicine, as well as in pesticide formulations for pest control in agriculture. Although the use of these compounds provides benefits to agribusiness, they can impact the environment, since a large part of these substances may reach the soil and water from the excreta of treated animals and following direct applications to crops. The present work had the objective of evaluating the dissipation behaviors of abamectin, doramectin, eprinomectin, ivermectin, and moxidectin in four native Brazilian soils of different textural classes (clay, sandy-clay, sandy, and sandy-clay-loam), following OECD Guideline 307. The studies were conducted in a climate chamber at 22 °C, 71% relative humidity, and protected from light. The dissipation studies were carried out with all drugs together, since no difference was verified when studies were done with each drug separately. The concentrations of the drugs in the soils were determined using an ultra-high performance liquid chromatograph coupled to a fluorescence detector or a tandem mass spectrometer. The dissipation half-life (DT50) values ranged from 9 to 16 days and the calculated GUS index values were in the range from -1.10 to 0.08, indicating low mobility of the drugs in the soils evaluated and low tendency for leaching. In addition, a field study was carried out to evaluate the dissipation of abamectin after application of a foliar pesticide in an orange crop. A DT50 of 9 days was determined, which was similar to that obtained under controlled conditions in the climate chamber (12 days), indicating that biotransformation was the primary process influencing the overall dissipation.

Vibrational extraction QuEChERS for analysis of antiparasitic agents in fish by liquid chromatography coupled with tandem mass spectrometry.

A method was developed for the analysis of 22 antiparasitic residues belonging to the benzoylurea, organophosphate, pyrimidinamine, pyrethrin and pyrethroid classes in salmon by liquid chromatography coupled with tandem mass spectrometry. Samples were extracted with acetonitrile-water as the extraction solvent with use of a vibrational shaking apparatus with a ceramic homogenizer. After extraction, the acetonitrile extracts were cleaned up by incubation at low temperature (-20 °C, 1 h) to remove fat, followed by dispersive solid-phase extraction using Z-Sep+ and primary-secondary amine as sorbents. Validation was performed following the 2002/657/EC and SANTE/11813/2017 guidelines. The trueness of the method ranged from 87% to 121% and precision ranged from 4.1% to 23.7%, with the exception of cyphenothrin, dicyclanil and azamethiphos. The method developed is particularly advantageous because the use of a vibrational shaker allows unattended extraction of samples and eliminates a laborious tissue disruption step, which increases sample throughput in the laboratory. The sample preparation and chromatographic separations can be performed in 5 and 4 h, respectively, for 36 samples. Graphical abstract.

Inclusion complexes and self-assembled cyclodextrin aggregates for increasing the solubility of benzimidazoles

Albendazole and fenbendazole are imidazole derivatives that exhibit broad spectrum activity against parasites, but the low solubility of these drugs considerably reduces their effectiveness. Complexation of albendazole and fenbendazole with cyclodextrins (ß-cyclodextrin and hydroxypropyl-ß-cyclodextrin) in both water and an aqueous solution of polyvinylpyrrolidone (PVP-k30) was studied to determine if it could increase the solubility and dissolution rate of the drugs. In an aqueous solution, ß-cyclodextrin increased the solubility of albendazole from 0.4188 to ~93.47 µg mL-1 (223×), and of fenbendazole from 0.1054 to 45.56 µg mL-1 (432×); hydroxypropyl-ß-cyclodextrin, on the other hand, increased solubility to ~443.06 µg mL-1 (1058×) for albendazole and ~159.36 µg mL-1 (1512×) for fenbendazole. The combination of hydroxypropyl-ß-cyclodextrin and polyvinylpyrrolidone enabled a solubility increase of 1412× (~591.22 µg mL-1) for albendazole and 1373× (~144.66 µg mL-1) for fenbendazole. The dissolution rate of the drugs was significantly increased in binary and ternary systems, with hydroxypropyl-ß-cyclodextrin proving to be more effective. The presence of the water-soluble PVP-k30 increased the dissolution rate and amorphization of the complexes. Analysis of the changes in displacement and the profile of the cyclodextrin bands in the 1H NMR spectra revealed a molecular interaction and pointed to an effective complexation in the drug/cyclodextrin systems. Monomeric forms and nanoclusters of cyclodextrins were observed in the drug/cyclodextrin systems, suggesting that the increase in solubility of the drugs in the presence of cyclodextrins should not be attributed only to the formation of inclusion complexes, but also to the formation of cyclodextrin aggregates

Comparative effects of the parasiticide ivermectin on survival and reproduction of adult sepsid flies.

Ivermectin is a veterinary pharmaceutical widely applied against parasites of livestock. Being effective against pests, it is also known to have lethal and sublethal effects on non-target organisms. While considerable research demonstrates the impact of ivermectin residues in livestock dung on the development and survival of dung feeding insect larvae, surprisingly little is known about its fitness effects on adults. We tested the impact of ivermectin on the survival of adult sepsid dung fly species (Diptera: Sepsidae) in the laboratory, using an ecologically relevant and realistic range of 69-1978 µg ivermectin/kg wet dung, and compared the sensitivities of larvae and adults in a phylogenetic framework. For one representative, relatively insensitive species, Sepsis punctum, we further investigated effects of ivermectin on female fecundity and male fertility. Moreover, we tested whether females can differentiate between ivermectin-spiked and non-contaminated dung in the wild. Adult sepsid flies exposed to ivermectin suffered increased mortality, whereby closely related species varied strongly in their sensitivity. Adult susceptibility to the drug correlated with larval susceptibility, showing a phylogenetic signal and demonstrating systemic variation in ivermectin sensitivity. Exposure of S. punctum females to even low concentrations of ivermectin lowered the number of eggs laid, while treatment of males reduced egg-to-adult offspring survival, presumably via impairment of sperm quality or quantity. The fitness impact was amplified when both parents were exposed. Lastly, sepsid flies did not discriminate against ivermectin-spiked dung in the field. Treatment of livestock with avermectins may thus have even more far-reaching sublethal ecological consequences than currently assumed via effects on adult dung-feeding insects.

Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

BACKGROUND: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. RESULTS: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. CONCLUSIONS: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates.

Effects of the Antiparasitic Drug Moxidectin in Cattle Dung on Zooplankton and Benthic Invertebrates and its Accumulation in a Water-Sediment System.

Two anthelmintic macrocyclic lactones-ivermectin and moxidectin-have revolutionized parasite control in cattle. These drugs are only partly metabolized by livestock, and the main route of excretion is via feces. In seasonally inundated floodplains, cattle feces come into direct contact with surface water. Important differences in pharmacokinetics and pharmacodynamics between these drugs may bear on their ecotoxicology in aquatic ecosystems. Moxidectin strongly binds to organic matter and thereby may be consumed in aquatic food webs, but there is a scarcity of data on toxicity to freshwater invertebrates. The objectives of this work were to determine the effect of moxidectin spiked in cattle dung on survival and growth of three representative aquatic invertebrates: the zooplankton Ceriodaphnia dubia, the amphipod Hyalella curvispina, and the snail Pomacea canaliculata. Moxidectin-laced dung was added in microcosms and concentrations were measured in water, sediment + dung, roots of the aquatic plant Salvinia biloba, and the aforementioned invertebrates. The influence of moxidectin on nutrient concentrations was also evaluated. Dung was spiked with moxidectin to attain concentrations of 750, 375 and 250 µg kg-1 dung fresh weight, approximating those found in cattle dung at days 2, 3, and 5 following subcutaneous injection. Concentrations of moxidectin in dung during the first week of excretion were lethally toxic for the tested invertebrate taxa. The persistence of moxidectin in the sediment + dung and the uptake of the drug in roots of S. biloba increase its potential exposure to aquatic food webs. Moxidectin also reduced the rate of release of soluble reactive phosphorus to the water.

Determination of 105 antibiotic, anti-inflammatory, antiparasitic agents and tranquilizers by LC-MS/MS based on an acidic QuEChERS-like extraction.

A procedure for screening 105 veterinary drugs in foods by liquid chromatography tandem mass-spectrometry (LC-MS/MS) is presented. Its scope encompasses raw materials of animal origin (milk, meat, fish, egg and fat) but also related processed ingredients and finished products commonly used and manufactured by food business operators. Due to the complexity of the matrices considered and to efficiently deal with losses during extraction and matrix effects during MS source ionisation, each sample was analysed twice, that is 'unspiked' and 'spiked at the screening target concentration' using a QuEChERS-like extraction. The entire procedure was validated according to the European Community Reference Laboratories Residues Guidelines. False-negative and false-positive rates were below 5% for all veterinary drugs whatever the food matrix. Effectiveness of the procedure was further demonstrated through participation to five proficiency tests and its ruggedness demonstrated in quality control operations by a second laboratory.

Aquatic toxicity of ivermectin in cattle dung assessed using microcosms.

Ivermectin (IVM) is a parasiticide widely used for livestock. It is a semisynthetic derivative of avermectin, a macrocyclic lactone produced by Streptomyces avermitilis. This drug is only partly metabolized by livestock; considerable amounts of parent drug are excreted mostly via feces. To simulate exposure of aquatic invertebrates and macrophytes to direct excretion of cattle dung into surface waters, a microcosm experiment with IVM spiked in cattle dung was conducted. The objectives of this study were to characterize accumulation of IVM in water, sediment+dung, roots of the floating fern Salvinia and the zooplankton Ceriodaphnia dubia, the amphipod Hyalella and the apple snail Pomacea; to determine the effect of this drug spiked in cattle dung on life-history traits of these invertebrates; and to evaluate the influence of IVM on aquatic nutrient cycling. Dung was spiked with IVM to attain concentrations of 1150, 458, 50 and 22µgkg-1dung fresh weight, approximating those found in cattle dung at days 3, 7, 16 and 29 following subcutaneous injection. Concentrations found in dung during the first week of excretion were lethally toxic to Ceriodaphnia dubia and Hyalella, whereas no mortality was observed in Pomacea. Concentrations of IVM in roots, sediment + dung and Pomacea increased significantly from the lowest to the highest treatment level. The effect of this drug on decomposition and release of nutrients from dung would have negative consequences for nutrient cycling in water. Increasing concentrations in sediment + dung with days of the experiment suggested that toxic concentrations would persist for an extended period in the water-sediment system. IVM represents an ecological risk for aquatic ecosystems, underscoring the need for livestock management strategies to limit its entry into water bodies.

Occurrence of antiparasitic pesticides in sediments near salmon farms in the northern Chilean Patagonia.

Growth of the aquaculture industry has triggered the need for research into the potential environmental impact of chemicals used by salmon farms to control diseases. In this study, the antiparasitic pesticides emamectin benzoate (EB), diflubenzuron (DI), teflubenzuron (TE), and cypermethrin (CP) were measured in sediments near salmon cages in southern Chile. Concentrations for EB were between 2.2 and 14.6ngg-1, while the benzoylphenyl ureas DI and TE were detected in the ranges of 0.1 to 1.2ngg-1 and 0.8 to 123.3ngg-1, respectively. These results were similar to data reported for the Northern Hemisphere. On the other hand, the pyrethroid CP was detected in higher concentrations, ranging from 18.0 to 1323.7ngg-1. According to reported toxicity data, this range represents a potential risk for benthic invertebrates. This report is the first baseline attempt at assessing antiparasitic pesticide levels in the Chilean Patagonia.

Development and Validation of a Reversed-Phase Chiral HPLC Method to Determine the Chiral Purity of Bulk Batches of (S)-Enantiomer in Afoxolaner.

Afoxolaner is a new antiparasitic molecule from the isoxazoline family that acts on insect acarine g-aminobutyric acid and glutamate receptors. Afoxolaner is a racemic mixture, which has a chiral center at the isoxazoline ring. A reversed-phase chiral HPLC method has been developed to determine the chiral purity of bulk batches of (S)-enantiomer in afoxolaner for the first time. This method can also be used to verify that afoxolaner is a racemic mixture, which was demonstrated by specific rotation. ChromSword, an artificial intelligence method development tool, was used for initial method development. The column selected for the final method was CHIRALPAK AD-RH (150 × 4.6 mm, 5 µm particle size), maintained at 45°C, and isocratic elution using water-isopropanol-acetonitrile (40 + 50 + 10, v/v/v) as the mobile phase with a detection wavelength of 312 nm. The run time for the method was 11 min. The resolution and selectivity factors of the two enantiomers were 2.3 and 1.24, respectively. LOQ and LOD of the method were 1.6 and 0.8 µg/mL, respectively. This method was appropriately validated according to International Conference on Harmonization guidelines for its intended use.

Simultaneous determination of abamectin homologs H 2 B 1a and H 2 B 1b in gel formulation by high performance liquid chromatography

ABSTRACT Abamectin is a drug with antiparasitic properties used in several pharmaceutical formulations. The objective of this research was to develop and validate a high performance liquid chromatographic (HPLC) method for quantification of the two abamectin homologs (H2B1a and H2B1b) in gel formulation. This HPLC method was validated using a LichroCart(r) 100 RP-18 (125 x 4 mm, 5 µm) column. The mobile phase contained of acetonitrile and water (95:5 v/v) with 1% acetic acid. The flow rate was 1.0 mL min-1 and UV detection was performed at 245 nm. Mobile phase solutions were prepared containing a nominal concentration 185.2 µg mL-1 H2B1a and 9.6 µg mL-1 H2B1b. The method displayed good linearity in the concentration range of 148.1 - 222.3 µg mL-1 and 7.7 - 11.5 µg mL-1, for H2B1a and H2B1b, respectively, with a correlation coefficient of (r)> 0.99 for both compounds, calculated by the least mean squares method. Detection limits (DLs) were 2.8 µg mL-1 and 1.2 µg mL-1 and quantitation limits (QLs) were 8.6 µg mL-1 and 3.8 µg mL-1, for H2B1a and H2B1b, respectively. The method is simple, economical and efficient for the quantitative determination of abamectin H2B1a and H2B1b homologs in pharmaceutical preparations.