Fentanyl and other New Psychoactive Synthetic Opioids. Challenges to Prevention and Treatment

ABSTRACT Synthetic opioids have played a significant role in the current opioid crisis in the United States (U.S.) and Canada and are a matter of concern worldwide. New psychoactive opioids (NPOs) are classified in the internationally recognized new psychoactive substances (NPSs) category. This group comprises compounds that may have been synthesized decades ago but appeared only recently in the illicit drug market. Such is the case of fentanyl, fentanyl analogs, and non-fentanyl opioids. Most NPOs have effects similar to morphine, including euphoria and analgesia, and can produce fatal respiratory depression. Here, we present an overview of the systemic and molecular effects of main NPOs, their classification, and their pharmacological properties. We first review the fentanyl group of NPOs, including the four compounds of clinical use (fentanyl, alfentanil, sufentanil, and remifentanil) and the veterinary drug carfentanil. We also provide essential information on non-medical fentanyl analogs and other synthetic opioids such as brorphine, etonitazene, and MT-45, used as adulterants in commonly misused drugs. This paper also summarizes the scarce literature on the use of NPOs in Mexico. It concludes with a brief review of the challenges to prevention and treatment posed by NPOs and some recommendations to face them.

Benzimidazole and its derivatives as cancer therapeutics: The potential role from traditional to precision medicine

Cancer is the second leading cause of mortality globally which remains a continuing threat to human health today. Drug insensitivity and resistance are critical hurdles in cancer treatment; therefore, the development of new entities targeting malignant cells is considered a high priority. Targeted therapy is the cornerstone of precision medicine. The synthesis of benzimidazole has garnered the attention of medicinal chemists and biologists due to its remarkable medicinal and pharmacological properties. Benzimidazole has a heterocyclic pharmacophore, which is an essential scaffold in drug and pharmaceutical development. Multiple studies have demonstrated the bioactivities of benzimidazole and its derivatives as potential anticancer therapeutics, either through targeting specific molecules or non-gene-specific strategies. This review provides an update on the mechanism of actions of various benzimidazole derivatives and the structure‒activity relationship from conventional anticancer to precision healthcare and from bench to clinics.

Mannich bases derivatives of 2-Phenyl-5-Benzimidazole sulfonic acid; Synthesis, Characterization, Computational studies and Biological evaluation

Abstract A new series of N-Mannich bases of 2-Phenyl-5-benzimidazole sulfonic acid have been synthesized through amino methylation reaction with secondary amines. The two moieties were held together through a methylene bridge, which comes from formaldehyde (Formalin Solution 37%) used in the reaction. Chemical structures of the newly synthesized compounds have been confirmed using FT-IR, 1HNMR and 13CNMR. Different in vitro assays including Anti-oxidant, Enzyme inhibition, Anti-microbial and Cytotoxicity assay were performed to evaluate the biological potential with reference to the standard drug. Among the synthesized library, compound 3a shows maximum alpha-glucosidase inhibition with an IC50 value of 66.66 µg/ml, compound 3d was found most toxic with LC50 value of 10.17 µg/ml. ADME evaluation studies were performed with the help of Molinspiration online software. Docking calculations were also performed. Given the importance of the nucleus involved, the synthesized compound might find extensive medicinal applications as reported in the literature.

New benzimidazole derivatives as inhibitors of Pteridine reductase 1: Design, molecular docking study and ADMET prediction

Pteridine reductase 1 (PTR1) is a unique enzyme required for survival of Leishmania species, a causative organism forthe disease leishmaniasis. We herein report the design, docking, and Absorption, Distribution, Metabolism, Excretion,Toxicity (ADMET) prediction studies of 2-substituted-5-[(6-substituted-1H-benzimidazol-2yl)methyl]azole derivatives(B1–B14) as PTR1 inhibitors. Molecular docking studies showed good binding interaction of the compounds withthe active site of pteridine reductase from Leishmania Major, with compounds B5 and B12 showing docking scoresof −61.5232 and −62.5897, respectively, which were comparable with the original ligand, dihydrobiopterin. Largesubstituents on the azole ring, as well as substitutions on sixth position of the benzimidazole ring, were found to befavorable for interaction with PTR1 active site. Physicochemical properties, bioactivity prediction, and toxicity profilesof the compounds were studied using the Molinspiration and admetSAR web servers. All compounds followed Lipinski’srule of five and can be considered as good oral candidates. Bioactivity prediction indicated that the compounds wereenzyme inhibitor, thus the rationale for designing PTR1 inhibitors was met. Most of the compounds were predicted tohave good ADMET properties in terms of Gastrointestinal (GI) absorption, absence of P-glycoprotein interaction, andLD50 values in rats. The designed molecules can be further explored for their antileishmanial activity

In vitro efficacy of new synthetic benzimidazole-related compounds against Schistosoma mansoni adult worms

Objective: To evaluate the in vitro antischistosomal activity of two new synthetic benzimidazole-related compounds: NBTP-OH and NBTP-F. Methods: Schistosoma adult worms were recovered from mice infected with Schistosoma mansoni cercaria, washed and then incubated in the culture media with different concentrations of compounds NBTP-OH and NBTP-F up to 72 h. Scanning electron microscopy was conducted to report morphological changes. Results: Incubation of adult Schistosoma mansoni with 10 µg/mL of NBTP-OH for 48 h killed 81.25% of worms. The calculated LC50 and LC90 72 h post-incubation were 6.8 µg/mL and 9.8 µg/ mL, respectively. Exposure of worms to 10 µg/mL of NBTP-F killed 89.5% of worms after 48 h, mostly males (83.3%), the LC50 and LC90 after 72 h of incubation were 4.8 µg/mL and 6.9 µg/mL, respectively. Worms incubated for 72 h with these compounds revealed swelling and deformity of oral sucker, disorganization and erosion of the tegument when examined with scanning electron microscopy. Conclusions: NBTP-OH and NBTP-F possess in vitro antischistosomal activities; however, in vivo studies should be conducted to examine their antischistosomal effects.

Design, synthesis and biological evaluation of peptidyl-prolyl cis-trans isomerase Pin1 inhibitors / 药学学报

Peptidyl-prolyl cis-trans isomerase Pin1 is over-expressed in prostate cancer cells and the level of expression correlates with the malignancy grade and prognosis in patients. In this work, twenty-one 2-(1H-benzimidazol-2-ylthio) acetic acid derivatives were designed and prepared with the aid of the crystal structure of Pin1 and our previous work. The chemical structures of the target compounds were confirmed by 1H NMR, 13C NMR, ESI-MS and IR. The inhibitory activity of compounds 6a-6i and 13a-13i against Pin1 were determined using a protease-coupled assay. The results indicated that twenty compounds were significantly superior to the positive control drug Juglone, and 6g, 6h and 13i exhibited the most potent Pin1 inhibitory activity, with IC50 values at the sub-micromolar level. The in vitro anti-proliferative activities of these analogs were evaluated by the MTT assay and several showed a moderate effect in human prostate cancer PC-3 cells. Molecular docking studies demonstrated that both the benzimidazole skeleton and the thioacetic acid fragment were indispensable for the compounds to interact with key residues in the catalytic domain of Pin1.

Discovery of highly selective and orally available benzimidazole-based phosphodiesterase 10 inhibitors with improved solubility and pharmacokinetic properties for treatment of pulmonary arterial hypertension

Optimization efforts were devoted to discover novel PDE10A inhibitors in order to improve solubility and pharmacokinetics properties for a long-term therapy against pulmonary arterial hypertension (PAH) starting from the previously synthesized inhibitor

Progress of researches on the development of non-benzimidazoles for the treatment of echinococcosis / 中国血吸虫病防治杂志

The long-term use of benzimidazoles for the treatment of echinococcosis may cause multiple adverse reactions and low compliance. A search for novel agents, as an alternative of benzimidazoles, is therefore of great significance for the treatment of echinococcosis. This review focuses on the progress of researches on non-benzimidazoles for the clinical treatment of echinococcosis, including anti-parasitic agents, anti-proliferative agents and plant extracts, so as to provide insights into the further development of non-benzimidazoles.

Absence of mutations associated with resistance to benzimidazole in the beta-tubulin gene of Ascaris suum

Abstract INTRODUCTION: Benzimidazoles are commonly used for the control of veterinary nematodes. Resistance to benzimidazoles has been associated with three single nucleotide polymorphisms in the β-tubulin gene of common nematodes. However, these mutations are infrequent in the genus Ascaris spp. METHODS: In order to determine mutations associated with benzimidazole resistance in Ascaris suum, worms were collected from slaughtered pigs and a partial region of the β-tubulin gene was sequenced. RESULTS: All parasites showed the wildtype genotype for codons 167, 198, and 200 of the β-tubulin gene. CONCLUSIONS: This is the first report of genetic sequences associated with benzimidazole resistance in A. suum.

Investigation of New Benzimidazole Derivative Compounds Effects on A549 Cell Line

Abstract Chronic inflammation is a common indication of several diseases, e.g. asthma, chronic obstructive pulmonary disease (COPD), atherosclerosis, etc. Benzimidazole derivatives are preferable compounds to design new analgesic and anti-inflammatory substances due to their unique biological features. We aimed to investigate the effect of a newly synthesized benzimidazole derivative, ORT-83, on A549 human lung adenocarcinoma cell line. ORT-83 was synthesized, and a non-cytotoxic concentration of ORT-83 on A549 cells was detected with MTT assay. To analyze the anti-inflammatory effect of ORT-83, an inflammatory cell culture model was established by stimulating A549 cell line with IL1-β (10 ng/ml). After 2 hours of treatment with IL1-β to induce inflammation, A549 cells were exposed to ORT-83 (0.78 µg/ml) for 24 hours. Thereafter gene expression analyses were performed with qRT-PCR. We found that ORT-83 significantly suppressed the gene expression levels of the proinflammatory cytokines; IL-6, NFkB, and TNF-α. However, the increased levels of IL-10 (2.8 folds) by IL-1β induction did not change after ORT-83 and/or dexamethasone (Dex: positive control) treatments. While Dex; a COX-2 inhibitor, reduced the COX-2 expression level in inflammatory cells from 10.03 folds to 0.71 folds, ORT-83 reduced its level to 4.37 folds. iNOS expression levels did not change in any experimental groups. In conclusion, we showed that ORT-83 exerted its anti-inflammatory effects by repressing the gene expression of proinflammatory cytokines in the inflammation-induced A549 cell line. Although ORT-83 had a weaker COX-2 inhibitory effect compared to Dex, it was shown to be still a strong anti-inflammatory compound.

In vitro efficacy of new synthetic benzimidazole-related compounds against Schistosoma mansoni adult worms

Objective: To evaluate the in vitro antischistosomal activity of two new synthetic benzimidazole-related compounds: NBTP-OH and NBTP-F. Methods: Schistosoma adult worms were recovered from mice infected with Schistosoma mansoni cercaria, washed and then incubated in the culture media with different concentrations of compounds NBTP-OH and NBTP-F up to 72 h. Scanning electron microscopy was conducted to report morphological changes. Results: Incubation of adult Schistosoma mansoni with 10 µg/mL of NBTP-OH for 48 h killed 81.25% of worms. The calculated LC50 and LC90 72 h post-incubation were 6.8 µg/mL and 9.8 µg/ mL, respectively. Exposure of worms to 10 µg/mL of NBTP-F killed 89.5% of worms after 48 h, mostly males (83.3%), the LC50 and LC90 after 72 h of incubation were 4.8 µg/mL and 6.9 µg/mL, respectively. Worms incubated for 72 h with these compounds revealed swelling and deformity of oral sucker, disorganization and erosion of the tegument when examined with scanning electron microscopy. Conclusions: NBTP-OH and NBTP-F possess in vitro antischistosomal activities; however, in vivo studies should be conducted to examine their antischistosomal effects.

MCC1019, a selective inhibitor of the Polo-box domain of Polo-like kinase 1 as novel, potent anticancer candidate

Polo-like kinase (PLK1) has been identified as a potential target for cancer treatment. Although a number of small molecules have been investigated as PLK1 inhibitors, many of which showed limited selectivity. PLK1 harbors a regulatory domain, the Polo box domain (PBD), which has a key regulatory function for kinase activity and substrate recognition. We report on 3-bromomethyl-benzofuran-2-carboxylic acid ethyl ester (designated: MCC1019) as selective PLK1 inhibitor targeting PLK1 PBD. Cytotoxicity and fluorescence polarization-based screening were applied to a library of 1162 drug-like compounds to identify potential inhibitors of PLK1 PBD. The activity of compound MC1019 against the PLK1 PBD was confirmed using fluorescence polarization and microscale thermophoresis. This compound exerted specificity towards PLK1 over PLK2 and PLK3. MCC1019 showed cytotoxic activity in a panel of different cancer cell lines. Mechanistic investigations in A549 lung adenocarcinoma cells revealed that MCC1019 induced cell growth inhibition through inactivation of AKT signaling pathway, it also induced prolonged mitotic arrest-a phenomenon known as mitotic catastrophe, which is followed by immediate cell death apoptosis and necroptosis. MCC1019 significantly inhibited tumor growth in a murine lung cancer model without affecting body weight or vital organ size, and reduced the growth of metastatic lesions in the lung. We propose MCC1019 as promising anti-cancer drug candidate.

Synthesis and characterization of silver(I) complex with mixed ligands saccharinate and 2-(2-pyridyl)bezimidazole / Síntesis y caracterización del complejo de plata(I) con ligandos mixtos sacarinato y 2-(2-piridil)bezimidazol / Síntese e caracterização do complexo de prata(I) com ligandos mistos sacarinato e 2-(2-piridil)benzimidazol

Abstract A new silver coordination compound [Ag(sac) (pbi)] was synthesized by reaction of silver(I) saccharinate with 2-(2-pyridyl)benzimidazole (pbi) in 64% yield. The characterization was performed by elemental analysis, IR, UV-Visible, XPS, 1H-NMR, and 13C-NMR spectroscopy. According to the results, silver is coordinating through three nitrogen atoms: one from saccharinate and the others from 2-(2-pyridyl) benzimidazole forming with this ligand a five-membered chelate ring.

Resumen Se sintetizó un nuevo compuesto de coordinación de plata, [Ag(sac)(pbi)], por reacción de sacarinato de plata(I) con 2-(2-piridil)bencimidazol (pbi) con un rendimiento de 64%. La caracterización se realizó por análisis elemental, espectroscopia IR, UV-Visible, XPS, 1H-RMN y 13C-RMN. De acuerdo con los resultados obtenidos la plata está coordinada a través de tres átomos de nitrógeno, uno del sacarinato y los dos restantes del 2-(2-piridil)-bencimidazol formando con este ligando un anillo quelato de cinco miembros.

Resumo O presente trabalho compreende a síntese de um novo composto de coordenação de prata, [Ag(sac)(pbi)], por reação de sacarinato de prata(I) com 2-(2-piridil)benzimidazol (pbi) com 64% de rendimento. A caracterização foi realizada por análise elementar, espectroscopia IV, UV-Visível, XPS, 1H-RMN e 13C-RMN. De acordo com os resultados obtidos, a prata é coordenada através de três átomos de nitrogênio, um do sacarinato e os outros dois do 2-(2-piridil)benzimidazol que formam com este ligando um anel de quelato de cinco membros.

Synthesis of benzimidazole and benzothiazole derivatives as a sirtuins 2 inhibitor / 药学学报

A series of novel benzimidazole and benzothiazole derivatives were designed and synthesized as inhibitors of SIRT1-SIRT3. The target compounds were synthesized from potassium O-ethyldithiocarbonate through a three-step route. The structures of the obtained compounds were elucidated by 1H NMR and HR-MS. Of all compounds, six showed potent SIRT2-inhibitory activities with IC50 values ranging from 2.8 to 21.2 μmol·L-1. Among them, compound 10c displayed the most potent SIRT2-inhibitory activities (IC50 = 2.8 μmol·L-1), with more than 35-fold selectivity over SIRT1 and SIRT3 (IC50>100 μmol·L-1).

Progress in researches of benzimidazole in treatment of echinococcosis / 中国血吸虫病防治杂志

Echinococcosis is a severe zoonosis parasitic disease and mainly caused by the larvae of Echinococcus granulosus and E. multilocularis. Because of the limitation of operation level,such as recurrence and death,the drug treatment is still the most important method in our country. Meanwhile,the annual number of drug treatments is far greater than surgical treatments. Drugs play a significant role in the preoperative reduction of lesions,reducing pain,extending the life of patients .This article re-views the status of animals treatment and clinical treatment of echinococcosis treated by the benzimidazole drugs and their new formulations,provides the basis for exploring the development direction of anti-echinococcosis drug treatment research.

POSIBLE RESISTENCIA DE Dictyocaulus viviparus AL FENBENDAZOL EN UN BOVINO / POSSIBLE RESISTANCE OF Dictyocaulus viviparus TO FENBENDAZOLE IN A BOVINE

Se describe un caso de posible resistencia al fenbendazol en una ternera Jersey infestada por Dictyocaulus viviparus. En el municipio de Entrerríos (Antioquia, Colombia), una hembra de la raza Jersey de 6 meses de edad, presentó un serio cuadro de bronco-neumonía, el cual no mejoró con la aplicación de fenbendazol y enrofloxacina como terapia de mantenimiento. En la necropsia, se observó un número elevado de parásitos vivos compatibles con Dictyocaulus viviparus, determinando una bronquitis verminosa. Este nematodo, el cual se trata rutinariamente con fenbendazol en las fincas lecheras colombianas, ha demostrado ser resistente frente algunos bencimidazoles; finalmente, se señalan las posibles causas de esta resistencia de Dictyocaulus viviparus en la ternera Jersey.

It describe the clinical case of a possible resistance to fenbendazole in a Jersey calf infested by Dictyocaulus viviparous described. In the municipality of Entrerrios (Antioquia, Colombia) a female Jersey breed of 6 months of age, presented serious sings of bronchopneumonia. which did not improve with the application of fenbendazole and enrofloxacin as maintenance therapy. At the necropsy, a large number of live parasites compatible with Dictyocaulus viviparus were observed, determining a verminous bronchitis. This nematode, which is routinely treated with fenbendazole in Colombian dairy farms, has been proved resistance when is trated with some benzimidazoles. This specific case shows the possible causes of the Dictyocaulus viviparus resistance in Jersey calf.

Resistência anti-helmíntica em rebanhos caprinos nos biomas Caatinga e Mata Atlântica / Anthelmintic resistance in goat herds in the Caatinga and Mata Atlântica biomes

A utilização de anti-helmínticos por longos períodos como principal medida de controle das parasitoses gastrintestinais de ruminantes levou a ineficácia aos levamisol, benzimidazóis e avermectinas. Este estudo descreve a atividade anti-helmíntica in vivo em populações naturais de nematoides trichostrongilídeos de caprinos. Foram selecionados 18 rebanhos provenientes dos biomas Caatinga (n=12) e Mata Atlântica (n=6), do Estado da Bahia, Brasil, criados em pastagens comunais em região semiárida. Grupos de oito a 10 animais foram tratados com albendazol (ABZ), ivermectina (IVM), levamisol (LEV), moxidectina (MOX) e closantel (CLOS). Os resultados do Teste de Redução da Contagem de Ovos nas Fezes indicaram resistência simultânea dos gêneros Haemonchus sp. e Trichostrongylus spp. para o ABZ, IVM, LEV, MOX e CLOS. As percentagens de eficácia variaram de 0-92%, 0-75%, 0-91%, 69-97% e 0-85% para o ABZ, IVM, LEV, MXD e CLOS, respectivamente, no bioma Caatinga e 0-59% para o ABZ e 9-59% para o IVM no bioma Mata Atlântica. Verificou-se nos rebanhos eficácia inferior a 95% para estes anti-helmínticos, com exceção de um único rebanho no qual a eficácia para MOX foi de 97%, o que sugere a presença de NGIs resistentes aos principais classes de anti-helmínticos em rebanhos caprinos destes biomas...

The use of anthelmintic drugs for long periods as the main measure control of gastrointestinal nematodes (GINs) has led to the inefficacy of levamisole, benzimidazoles and macrocyclic lactones. This study describes the in vivo anthelmintic activity against natural trichostrongyle nematodes populations in goats. We selected 18 herds from the Caatinga (n=12) and Mata Atlântica (n=6) biomes, Bahia State, Brazil, raised in communal pastures in semiarid region. Groups of 8 to 10 goats were treated with albendazole (ABZ), ivermectin (IVM), levamisole (LEV), moxidectin (MOX), and closantel (CLOS). The results of the Fecal Egg Count Reduction Test indicated simultaneous resistance of Haemonchus sp. and Trichostrongylus spp. genera against albendazole (ABZ), ivermectin (IVM), levamisole (LEV), moxidectin (MOX), and closantel (CLOS). The efficacy percentages ranged from 0 to 92%, 0 to 75%, 0 to 91%, 69 to 97%, and 0 to 85% for ABZ, IVM, LEV, MXD and CLOS respectively in the Caatinga bioma, and 0 to 59% for ABZ and 9 to 59% for IVM in the Mata Atlântica biome. Most herds showed efficacy lower than 95% for anthelmintics, with the exception of one herd in which the efficacy for MOX was 97%. The results indicated the presence of GINs resistant to main anthelmintics classes in goat herds in these biomes...

Benzimidazole derivatives: search for GI-friendly anti-inflammatory analgesic agents

Non-steroidal anti-inflammatory drugs (NSAIDs) have been successfully used for the alleviation of pain and inflammation in the past and continue to be used daily by millions of patients worldwide. However, gastrointestinal (GI) toxicity associated with NSAIDs is an important medical and socioeconomic problem. Local generation of various reactive oxygen species plays a significant role in the formation of gastric ulceration associated with NSAIDs therapy. Co-medication of antioxidants along with NSAIDs has been found to be beneficial in the prevention of GI injury. This paper describes the synthesis and biological evaluation of N-1-(phenylsulfonyl)-2-methylamino-substituted-1H-benzimidazole derivatives as anti-inflammatory analgesic agents with lower GI toxicity. Studies in vitro and in vivo demonstrated that the antioxidant activity of the test compounds decreased GI toxicity.

JVG9, a benzimidazole derivative, alters the surface and cytoskeleton of Trypanosoma cruzi bloodstream trypomastigotes

Trypanosoma cruzi has a particular cytoskeleton that consists of a subpellicular network of microtubules and actin microfilaments. Therefore, it is an excellent target for the development of new anti-parasitic drugs. Benzimidazole 2-carbamates, a class of well-known broad-spectrum anthelmintics, have been shown to inhibit the in vitro growth of many protozoa. Therefore, to find efficient anti-trypanosomal (trypanocidal) drugs, our group has designed and synthesised several benzimidazole derivatives. One, named JVG9 (5-chloro-1H-benzimidazole-2-thiol), has been found to be effective against T. cruzi bloodstream trypomastigotes under both in vitro and in vivo conditions. Here, we present the in vitro effects observed by laser scanning confocal and scanning electron microscopy on T. cruzi trypomastigotes. Changes in the surface and the distribution of the cytoskeletal proteins are consistent with the hypothesis that the trypanocidal activity of JVG9 involves the cytoskeleton as a target.

Frequency of benzimidazole resistance in Haemonchus contortus populations isolated from buffalo, goat and sheep herds / Frequência da resistência ao benzimidazol em populações de Haemonchus contortus isoladas de rebanhos de bubalinos, caprinos e ovinos

Anthelmintic resistance is an increasing problem that threatens livestock production worldwide. Understanding of the genetic basis of benzimidazole resistance recently allowed the development of promising molecular diagnostic tools. In this study, isolates of Haemonchus contortus obtained from goats, sheep and buffaloes raised in Brazil were screened for presence of the polymorphism Phe200Tyr in the β-tubulin 1 gene, which confers resistance to benzimidazole. The allelic frequency of the mutation conferring resistance ranged from 7% to 43%, and indicated that resistance to benzimidazole could be found in nematodes isolated from all the ruminant species surveyed. Although significant variation in the frequency of the F200Y mutation was observed between different herds or host species, no significant variation could be found in populations isolated from animals within the same herd. These findings suggest that screening of samples from a few animals has the potential to provide information about the benzimidazole resistance status of the entire herd, which would enable a considerable reduction in the costs of diagnosis for the producer. Molecular diagnosis has practical advantages, since it can guide the choice of anthelmintic drug that will be used, before its application in the herd, thus reducing the economic losses driven by anthelmintic resistance.

A resistência aos anti-helmínticos é um problema crescente que ameaça a produção pecuária em todo o mundo. A compreensão da base genética da resistência ao benzimidazol permitiu, recentemente, o desenvolvimento de métodos diagnósticos moleculares promissores. Neste estudo, isolados de Haemonchus contortus obtidos a partir de rebanhos de caprinos, ovinos e bubalinos criados no Brasil foram avaliados quanto à presença do polimorfismo F200Y no gene da β-tubulina1, o qual confere resistência ao benzimidazol. A frequência alélica da mutação variou de 7% a 43%, indicando que a resistência ao benzimidazol pode ser encontrada em nematoides isolados a partir de todas as espécies de ruminantes pesquisadas. Embora tenha sido observada variação significativa das frequências de mutação F200Y entre rebanhos/espécies hospedeiros distintos, não foi encontrada variação significativa entre populações isoladas de animais dentro de um mesmo rebanho. Estes achados sugerem que a avaliação de amostras de alguns poucos animais tem o potencial de fornecer informações sobre o nível de resistência ao benzimidazol de todo o rebanho, possibilitando uma redução considerável dos custos de diagnóstico para o produtor. O diagnóstico molecular apresenta vantagens práticas, uma vez que pode guiar a escolha da base anti-helmíntica a ser utilizada antes da sua aplicação no rebanho, reduzindo, portanto, as perdas ocasionadas pela resistência aos fármacos anti-helmínticos.