The Experts below are selected from a list of 546 Experts worldwide ranked by ideXlab platform
B.c. Hosking - One of the best experts on this subject based on the ideXlab platform.
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The comparative efficacy of abamectin, Monepantel and an abamectin/derquantel combination against fourth-stage larvae of a macrocyclic lactone-resistant Teladorsagia spp. isolate infecting sheep.
Veterinary Parasitology, 2012Co-Authors: S D George, P A Stein, A J George, B.c. Hosking, P.f. Rolfe, Wolfgang SeewaldAbstract:Anthelmintic resistance by gastrointestinal nematodes of sheep continues to be an issue of global interest. While the recent introduction in some countries of one or two new anthelmintic classes (amino-acetonitrile derivatives [AAD] and spiroindoles [SI]) has been welcomed, it is important that there is no relaxation in parasite control and the management of drug resistance. Monepantel (an AAD) was the first new anthelmintic to be approved for use (New Zealand, 2009) and was followed a year later in the same country by a combination of derquantel (a SI) and abamectin. The present study determined the efficacy of the new anthelmintic products and abamectin against fourth-stage larvae of macrocyclic lactone-resistant Teladorsagia spp. in lambs. Efficacies were calculated by comparing post-mortem nematode burdens of treated animals with those of untreated control sheep, and were 98.5, 86.3 and 34.0% for Monepantel, abamectin/derquantel and abamectin, respectively. The nematode burdens of Monepantel- and abamectin/derquantel-treated sheep were significantly lower than those sheep treated with abamectin and the untreated controls. Similarly, the burden of the Monepantel group was significantly lower than that of the abamectin/derquantel group. These findings provide an opportunity to reinforce the recommendation that farmers and animal health advisors need to know the resistance status of nematode populations on subject farms to ensure effective control programs are designed and implemented. Such control programs should include an appropriate choice of anthelmintic(s), monitoring parasite burdens for correct timing of treatments, and pasture management to reduce larval challenge balanced with the maintenance of drug-susceptible populations in refugia.
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Efficacy of Monepantel and anthelmintic combinations against multiple-resistant Haemonchus contortus in sheep, including characterisation of the nematode isolate.
Veterinary parasitology, 2011Co-Authors: K Baker, S D George, P A Stein, Wolfgang Seewald, P.f. Rolfe, B.c. HoskingAbstract:Abstract Three experiments defined the resistance profile of a population of Haemonchus contortus , which was shown to express multiple resistances to the benzimidazole, levamisole, macrocyclic lactone and salicylanilide anthelmintic classes when given as a registered combination. Study 1 was a faecal egg count reduction (FECR) test and the efficacies for the anthelmintics were Monepantel, 100%; abamectin + levamisole + oxfendazole, 40.0%; and abamectin + levamisole + oxfendazole + naphthalophos, 100%. No larvae were recovered from the post-treatment cultures for Monepantel or the 4-way treatment, and for the 3-way treatment the culture was 100% Haemonchus spp. Efficacies in Study 2 were calculated from mean post-mortem nematode burdens of H. contortus and were levamisole + oxfendazole, 3.1%; abamectin + levamisole + oxfendazole, 5.0%; ivermectin, 0.4%; moxidectin, 28.4% and closantel, 70.2%. Study 3 was also a FECR test that resulted in efficacies of 100% for Monepantel and 83.0% for a formulated 4-way combination of abamectin + levamisole + albendazole + closantel. Larvae recovered from the post-treatment culture for the combination-treated sheep were all Haemonchus spp. Multi-resistant parasites such as examined in these studies are a continuing challenge to be managed by farmers and their advisors. Control programs must be planned and well-managed, and should include on-farm testing for anthelmintic resistance, monitoring of nematode burdens (by FEC and larval culture) to determine appropriate treatment times and the management of pastures to reduce the overall parasite challenge. This should be in balance with the generation, use and maintenance of drug-susceptible nematode populations in refugia.
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The efficacy of Monepantel against naturally acquired inhibited and developing fourth-stage larvae of Teladorsagia circumcincta in sheep in the United Kingdom.
Veterinary parasitology, 2011Co-Authors: C Ramage, D J Bartley, F Jackson, R Cody, B.c. HoskingAbstract:The inhibition of Teladorsagia and other nematode genera at the early fourth-stage is a biological process that allows the parasites to survive in their host in a dormant state when prevailing conditions may otherwise kill them or prevent their progeny from surviving in the external environment. A study was conducted in Scotland to evaluate the efficacy of Monepantel, an amino-acetonitrile derivative, against natural infections of inhibited fourth-stage Teladorsagia spp. larvae. At necropsy it was determined that the untreated control sheep were additionally infected with developing fourth-stage Teladorsagia spp. larvae and this is the first published evidence on the efficacy of Monepantel against natural infections of this parasite and stage. The study sheep, which had grazed on naturally contaminated pastures since birth, were transferred to indoor housing after a subset of animals was examined to confirm the presence of inhibited larvae within the study population prior to the experiment. After 14 days of housing, Monepantel was orally administered at 2.5 mg/kg to half of the animals. The sheep were necropsied seven days later and their parasite burdens recovered for the determination of efficacy, which was 99.7% for the inhibited stages and 99.3% for the developing fourth-stages. In conclusion, Monepantel dosed orally at 2.5 mg/kg is a highly effective treatment against naturally acquired infections of inhibited and developing fourth-stage larvae of Teladorsagia spp.
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Safety and efficacy against fourth-stage gastrointestinal nematode larvae, of Monepantel in 6-week old lambs.
Veterinary Parasitology, 2011Co-Authors: P A Stein, S D George, P.f. Rolfe, B.c. HoskingAbstract:Abstract A controlled, blinded study was undertaken in 6-week old, pre-weaned lambs to demonstrate the safety and efficacy against fourth-stage gastrointestinal nematode larvae, of Monepantel administered per os at 2.5 mg/kg body weight. Worm burdens of 10 Monepantel-treated lambs were compared to those from 10 untreated control lambs. Geometric mean derived efficacies of 100, 100, 96.4 and 99.9% were demonstrated against Haemonchus contortus , Teladorsagia spp., Cooperia curticei and Trichostrongylus colubriformis , respectively. These results, considered in the light of an earlier series of studies demonstrating the efficacy of Monepantel in older animals, and an absence of any adverse events, provides strong support for the use of Monepantel as a safe and effective anthelmintic in lambs from six weeks of age.
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Minimising the development of anthelmintic resistance, and optimising the use of the novel anthelmintic Monepantel, for the sustainable control of nematode parasites in Australian sheep grazing systems.
Australian veterinary journal, 2011Co-Authors: R.j. Dobson, B.c. Hosking, P.f. Rolfe, R.b. Besier, S. C. J. Love, John W. Larsen, J.n. BaileyAbstract:Objective To compare the risk of different treatment scenarios on selecting for anthelmintic resistance on Australian sheep farms. Design A computer simulation model predicted populations of Trichostrongylus colubriformis, Haemonchus contortus or Teladorsagia (Ostertagia) circumcincta, and the frequency of anthelmintic resistance genes. Method Nematode populations and the progression of drug resistance for a variety of treatment options and management practices in sheep-rearing areas of Western Australia (WA), Victoria (VIC) and New South Wales (NSW) were simulated. A scoring system was devised to measure the success of each option in delaying resistance to each anthelmintic and in controlling nematode populations. Results The best option at all sites was combining the new anthelmintic (Monepantel) with a triple mixture of benzimidazole, levamisole and abamectin (COM). The next best option was: in NSW, rotation at each treatment between Monepantel, moxidectin and COM; in VIC, rotation at each treatment between Monepantel and COM; and in WA, rotation at each treatment between Monepantel (used in winter) and COM or moxidectin (used in summer-autumn). In WA, rapid selection for resistance occurred as a consequence of summer-autumn treatments; however, if a small percentage of adult stock were left untreated then this selection could be greatly reduced. Despite purposely assuming relatively high resistance to benzimidazole and levamisole, COM was still effective in controlling worms and delaying resistance. Conclusions Because of cost constraints, it may not be feasible or profitable for producers to always use the combination of all drugs. However, the second-and third-best options still considerably slowed the development of anthelmintic resistance.
P A Stein - One of the best experts on this subject based on the ideXlab platform.
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the comparative efficacy of abamectin Monepantel and an abamectin derquantel combination against fourth stage larvae of a macrocyclic lactone resistant teladorsagia spp isolate infecting sheep
Veterinary Parasitology, 2012Co-Authors: S D George, P A Stein, A J George, Barry C. Hosking, Peter F. Rolfe, Wolfgang SeewaldAbstract:Abstract Anthelmintic resistance by gastrointestinal nematodes of sheep continues to be an issue of global interest. While the recent introduction in some countries of one or two new anthelmintic classes (amino-acetonitrile derivatives [AAD] and spiroindoles [SI]) has been welcomed, it is important that there is no relaxation in parasite control and the management of drug resistance. Monepantel (an AAD) was the first new anthelmintic to be approved for use (New Zealand, 2009) and was followed a year later in the same country by a combination of derquantel (a SI) and abamectin. The present study determined the efficacy of the new anthelmintic products and abamectin against fourth-stage larvae of macrocyclic lactone-resistant Teladorsagia spp. in lambs. Efficacies were calculated by comparing post-mortem nematode burdens of treated animals with those of untreated control sheep, and were 98.5, 86.3 and 34.0% for Monepantel, abamectin/derquantel and abamectin, respectively. The nematode burdens of Monepantel- and abamectin/derquantel-treated sheep were significantly lower than those sheep treated with abamectin and the untreated controls. Similarly, the burden of the Monepantel group was significantly lower than that of the abamectin/derquantel group. These findings provide an opportunity to reinforce the recommendation that farmers and animal health advisors need to know the resistance status of nematode populations on subject farms to ensure effective control programs are designed and implemented. Such control programs should include an appropriate choice of anthelmintic(s), monitoring parasite burdens for correct timing of treatments, and pasture management to reduce larval challenge balanced with the maintenance of drug-susceptible populations in refugia.
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The comparative efficacy of abamectin, Monepantel and an abamectin/derquantel combination against fourth-stage larvae of a macrocyclic lactone-resistant Teladorsagia spp. isolate infecting sheep.
Veterinary Parasitology, 2012Co-Authors: S D George, P A Stein, A J George, B.c. Hosking, P.f. Rolfe, Wolfgang SeewaldAbstract:Anthelmintic resistance by gastrointestinal nematodes of sheep continues to be an issue of global interest. While the recent introduction in some countries of one or two new anthelmintic classes (amino-acetonitrile derivatives [AAD] and spiroindoles [SI]) has been welcomed, it is important that there is no relaxation in parasite control and the management of drug resistance. Monepantel (an AAD) was the first new anthelmintic to be approved for use (New Zealand, 2009) and was followed a year later in the same country by a combination of derquantel (a SI) and abamectin. The present study determined the efficacy of the new anthelmintic products and abamectin against fourth-stage larvae of macrocyclic lactone-resistant Teladorsagia spp. in lambs. Efficacies were calculated by comparing post-mortem nematode burdens of treated animals with those of untreated control sheep, and were 98.5, 86.3 and 34.0% for Monepantel, abamectin/derquantel and abamectin, respectively. The nematode burdens of Monepantel- and abamectin/derquantel-treated sheep were significantly lower than those sheep treated with abamectin and the untreated controls. Similarly, the burden of the Monepantel group was significantly lower than that of the abamectin/derquantel group. These findings provide an opportunity to reinforce the recommendation that farmers and animal health advisors need to know the resistance status of nematode populations on subject farms to ensure effective control programs are designed and implemented. Such control programs should include an appropriate choice of anthelmintic(s), monitoring parasite burdens for correct timing of treatments, and pasture management to reduce larval challenge balanced with the maintenance of drug-susceptible populations in refugia.
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Efficacy of Monepantel and anthelmintic combinations against multiple-resistant Haemonchus contortus in sheep, including characterisation of the nematode isolate.
Veterinary parasitology, 2011Co-Authors: K Baker, S D George, P A Stein, Wolfgang Seewald, P.f. Rolfe, B.c. HoskingAbstract:Abstract Three experiments defined the resistance profile of a population of Haemonchus contortus , which was shown to express multiple resistances to the benzimidazole, levamisole, macrocyclic lactone and salicylanilide anthelmintic classes when given as a registered combination. Study 1 was a faecal egg count reduction (FECR) test and the efficacies for the anthelmintics were Monepantel, 100%; abamectin + levamisole + oxfendazole, 40.0%; and abamectin + levamisole + oxfendazole + naphthalophos, 100%. No larvae were recovered from the post-treatment cultures for Monepantel or the 4-way treatment, and for the 3-way treatment the culture was 100% Haemonchus spp. Efficacies in Study 2 were calculated from mean post-mortem nematode burdens of H. contortus and were levamisole + oxfendazole, 3.1%; abamectin + levamisole + oxfendazole, 5.0%; ivermectin, 0.4%; moxidectin, 28.4% and closantel, 70.2%. Study 3 was also a FECR test that resulted in efficacies of 100% for Monepantel and 83.0% for a formulated 4-way combination of abamectin + levamisole + albendazole + closantel. Larvae recovered from the post-treatment culture for the combination-treated sheep were all Haemonchus spp. Multi-resistant parasites such as examined in these studies are a continuing challenge to be managed by farmers and their advisors. Control programs must be planned and well-managed, and should include on-farm testing for anthelmintic resistance, monitoring of nematode burdens (by FEC and larval culture) to determine appropriate treatment times and the management of pastures to reduce the overall parasite challenge. This should be in balance with the generation, use and maintenance of drug-susceptible nematode populations in refugia.
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Safety and efficacy against fourth-stage gastrointestinal nematode larvae, of Monepantel in 6-week old lambs.
Veterinary Parasitology, 2011Co-Authors: P A Stein, S D George, P.f. Rolfe, B.c. HoskingAbstract:Abstract A controlled, blinded study was undertaken in 6-week old, pre-weaned lambs to demonstrate the safety and efficacy against fourth-stage gastrointestinal nematode larvae, of Monepantel administered per os at 2.5 mg/kg body weight. Worm burdens of 10 Monepantel-treated lambs were compared to those from 10 untreated control lambs. Geometric mean derived efficacies of 100, 100, 96.4 and 99.9% were demonstrated against Haemonchus contortus , Teladorsagia spp., Cooperia curticei and Trichostrongylus colubriformis , respectively. These results, considered in the light of an earlier series of studies demonstrating the efficacy of Monepantel in older animals, and an absence of any adverse events, provides strong support for the use of Monepantel as a safe and effective anthelmintic in lambs from six weeks of age.
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Effect of route of administration on the efficacy and pharmacokinetics of an experimental formulation of the amino-acetonitrile derivative Monepantel in sheep.
Veterinary Record, 2010Co-Authors: B.c. Hosking, P A Stein, Wolfgang Seewald, Daniela Karadzovska, John K. House, Jerome M. GiraudelAbstract:The effect of the route of administration (oral, intraruminal and intra-abomasal) on the efficacy and pharmacokinetics of the new anthelmintic Monepantel in sheep was investigated. The target nematodes were fourth-stage Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis and Cooperia curticei. A clear difference in efficacy was identified between the routes of administration, although the difference did not consistently reach statistical significance; oral treatment was most effective, followed by intraruminal and then intra-abomasal administration. The same pattern was observed in the pharmacokinetic analysis, with lambs treated orally having more favourable exposure to Monepantel and its sulfone metabolite (albeit in all but one instance not significantly different) than the lambs treated by the other routes of administration, which were very similar for most parameters.
Ronald Kaminsky - One of the best experts on this subject based on the ideXlab platform.
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new advancement in anthelmintic drugs in veterinary medicine
Trends in Parasitology, 2013Co-Authors: C Epe, Ronald KaminskyAbstract:Anthelmintic treatment of nematode infections remains the mainstay of worm control in farm and companion animals. However, control is threatened by the occurrence of drug resistant nematodes. In recent years, three new anthelmintics have been introduced to the market. Here, we describe the main features including mode of action, availability, spectrum, dose, tolerability, safety, and resistance of emodepside, Monepantel, and derquantel.
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Efficacy of Monepantel, derquantel and abamectin against adult stages of a multi-resistant Haemonchus contortus isolate
Parasitology Research, 2012Co-Authors: Heinz Sager, Beatrice Bapst, Günther A. Strehlau, Ronald KaminskyAbstract:Drug resistance in gastrointestinal nematodes is a severe problem for sheep farmers. With the recent introduction of Monepantel (Zolvix®) and of derquantel plus abamectin (Startect®) in New Zealand, two new anthelmintic classes will be available to control gastrointestinal nematodes. While Monepantel covers a broad spectrum of nematodes, the efficacy of derquantel is mid-spectrum and limited to a smaller number of species and stages. The combination of derquantel and abamectin allows to enlarge the spectrum and to cover most parasitic nematodes in sheep. However, the question remained open, if the efficacy of the new anthelmintics can be maintained in the presence of severe anthelmintic resistance. The present study investigated the efficacy against adult stages of a multi-resistant Haemonchus contortus isolate. While Monepantel resulted in 100 % elimination, derquantel in combination with abamectin resulted in efficacies
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efficacy of Monepantel derquantel and abamectin against adult stages of a multi resistant haemonchus contortus isolate
Parasitology Research, 2012Co-Authors: Heinz Sager, G Strehlau, Beatrice Bapst, Ronald KaminskyAbstract:Drug resistance in gastrointestinal nematodes is a severe problem for sheep farmers. With the recent introduction of Monepantel (Zolvix®) and of derquantel plus abamectin (Startect®) in New Zealand, two new anthelmintic classes will be available to control gastrointestinal nematodes. While Monepantel covers a broad spectrum of nematodes, the efficacy of derquantel is mid-spectrum and limited to a smaller number of species and stages. The combination of derquantel and abamectin allows to enlarge the spectrum and to cover most parasitic nematodes in sheep. However, the question remained open, if the efficacy of the new anthelmintics can be maintained in the presence of severe anthelmintic resistance. The present study investigated the efficacy against adult stages of a multi-resistant Haemonchus contortus isolate. While Monepantel resulted in 100 % elimination, derquantel in combination with abamectin resulted in efficacies <95 % (faecal egg counts and worm counts).
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Differences in efficacy of Monepantel, derquantel and abamectin against multi-resistant nematodes of sheep
Parasitology Research, 2011Co-Authors: Ronald Kaminsky, Barry C. Hosking, Peter F. Rolfe, Beatrice Bapst, Brooke A. Allan, Günther A. Strehlau, Philip A. Stein, Heinz SagerAbstract:Drug resistance has become a global phenomenon in gastrointestinal nematodes of sheep, particularly resistance to macrocyclic lactones. New anthelmintics are urgently needed for both the control of infections with multi-resistant nematodes in areas where classical anthelmintics are no longer effective, and the prevention of the spread of resistance in areas where the problem is not as severe. Recently, two new active ingredients became commercially available for the treatment of nematode infections in sheep, Monepantel (Zolvix®) and derquantel, the latter used only in a formulated combination with the macrocyclic lactone, abamectin (Startect®). In order to assess the potential of the new actives for the control and prevention of spread of anthelmintic resistance, two characterized multi-resistant field isolates from Australia were used in a GLP (good laboratory practice) conducted efficacy study in sheep. Eight infected sheep in each group were treated orally according to the product labels with 2.5 mg/kg body weight Monepantel, 0.2 mg/kg abamectin, or with the combination of 2.0 mg/kg derquantel and 0.2 mg/kg abamectin. The results demonstrate that Monepantel was fully effective against multi-resistant species, Trichostrongylus colubriformis and Haemonchus contortus (99.9%). In contrast, the combination of derquantel and abamectin was effective against T. colubriformis (99.9%), but was not effective against larval stages of the barber's pole worm H. contortus (18.3%).
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Phylogenomics of Ligand-Gated Ion Channels Predicts Monepantel Effect
PLoS pathogens, 2010Co-Authors: Lucien Rufener, Ronald Kaminsky, Pascal Mäser, Jennifer Keiser, Daniel NilssonAbstract:The recently launched veterinary anthelmintic drench for sheep (Novartis Animal Health Inc., Switzerland) containing the nematocide Monepantel represents a new class of anthelmintics: the amino-acetonitrile derivatives (AADs), much needed in view of widespread resistance to the classical drugs. Recently, it was shown that the ACR-23 protein in Caenorhabditis elegans and a homologous protein, MPTL-1 in Haemonchus contortus, are potential targets for AAD action. Both proteins belong to the DEG-3 subfamily of acetylcholine receptors, which are thought to be nematode-specific, and different from those targeted by the imidazothiazoles (e.g. levamisole). Here we provide further evidence that Cel-ACR-23 and Hco-MPTL-1-like subunits are involved in the Monepantel-sensitive phenotype. We performed comparative genomics of ligand-gated ion channel genes from several nematodes and subsequently assessed their sensitivity to anthelmintics. The nematode species in the Caenorhabditis genus, equipped with ACR-23/MPTL-1-like receptor subunits, are sensitive to Monepantel (EC50 43 µM). Genome sequence information has long been used to identify putative targets for therapeutic intervention. We show how comparative genomics can be applied to predict drug sensitivity when molecular targets of a compound are known or suspected.
Heinz Sager - One of the best experts on this subject based on the ideXlab platform.
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Efficacy of Monepantel, derquantel and abamectin against adult stages of a multi-resistant Haemonchus contortus isolate
Parasitology Research, 2012Co-Authors: Heinz Sager, Beatrice Bapst, Günther A. Strehlau, Ronald KaminskyAbstract:Drug resistance in gastrointestinal nematodes is a severe problem for sheep farmers. With the recent introduction of Monepantel (Zolvix®) and of derquantel plus abamectin (Startect®) in New Zealand, two new anthelmintic classes will be available to control gastrointestinal nematodes. While Monepantel covers a broad spectrum of nematodes, the efficacy of derquantel is mid-spectrum and limited to a smaller number of species and stages. The combination of derquantel and abamectin allows to enlarge the spectrum and to cover most parasitic nematodes in sheep. However, the question remained open, if the efficacy of the new anthelmintics can be maintained in the presence of severe anthelmintic resistance. The present study investigated the efficacy against adult stages of a multi-resistant Haemonchus contortus isolate. While Monepantel resulted in 100 % elimination, derquantel in combination with abamectin resulted in efficacies
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efficacy of Monepantel derquantel and abamectin against adult stages of a multi resistant haemonchus contortus isolate
Parasitology Research, 2012Co-Authors: Heinz Sager, G Strehlau, Beatrice Bapst, Ronald KaminskyAbstract:Drug resistance in gastrointestinal nematodes is a severe problem for sheep farmers. With the recent introduction of Monepantel (Zolvix®) and of derquantel plus abamectin (Startect®) in New Zealand, two new anthelmintic classes will be available to control gastrointestinal nematodes. While Monepantel covers a broad spectrum of nematodes, the efficacy of derquantel is mid-spectrum and limited to a smaller number of species and stages. The combination of derquantel and abamectin allows to enlarge the spectrum and to cover most parasitic nematodes in sheep. However, the question remained open, if the efficacy of the new anthelmintics can be maintained in the presence of severe anthelmintic resistance. The present study investigated the efficacy against adult stages of a multi-resistant Haemonchus contortus isolate. While Monepantel resulted in 100 % elimination, derquantel in combination with abamectin resulted in efficacies <95 % (faecal egg counts and worm counts).
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Differences in efficacy of Monepantel, derquantel and abamectin against multi-resistant nematodes of sheep
Parasitology Research, 2011Co-Authors: Ronald Kaminsky, Barry C. Hosking, Peter F. Rolfe, Beatrice Bapst, Brooke A. Allan, Günther A. Strehlau, Philip A. Stein, Heinz SagerAbstract:Drug resistance has become a global phenomenon in gastrointestinal nematodes of sheep, particularly resistance to macrocyclic lactones. New anthelmintics are urgently needed for both the control of infections with multi-resistant nematodes in areas where classical anthelmintics are no longer effective, and the prevention of the spread of resistance in areas where the problem is not as severe. Recently, two new active ingredients became commercially available for the treatment of nematode infections in sheep, Monepantel (Zolvix®) and derquantel, the latter used only in a formulated combination with the macrocyclic lactone, abamectin (Startect®). In order to assess the potential of the new actives for the control and prevention of spread of anthelmintic resistance, two characterized multi-resistant field isolates from Australia were used in a GLP (good laboratory practice) conducted efficacy study in sheep. Eight infected sheep in each group were treated orally according to the product labels with 2.5 mg/kg body weight Monepantel, 0.2 mg/kg abamectin, or with the combination of 2.0 mg/kg derquantel and 0.2 mg/kg abamectin. The results demonstrate that Monepantel was fully effective against multi-resistant species, Trichostrongylus colubriformis and Haemonchus contortus (99.9%). In contrast, the combination of derquantel and abamectin was effective against T. colubriformis (99.9%), but was not effective against larval stages of the barber's pole worm H. contortus (18.3%).
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Quarantine treatment of sheep with Monepantel--rapidity of fecal egg count reduction.
Veterinary Parasitology, 2010Co-Authors: Heinz Sager, Ronald Kaminsky, P.f. Rolfe, G. Strehlau, Brooke A. Allan, B.c. HoskingAbstract:In the presence of multiple anthelmintic resistance, effective quarantine treatment of sheep entering a farm has become a crucial tool in nematode management. In the present work, the use of the amino-acetonitrile derivative, Monepantel as a quarantine treatment was investigated. Of special interest was the rapidity of decrease in fecal egg counts (FEC) compared to other anthelmintics used in sheep. In three different studies, sheep were either infected with Haemonchus contortus of known resistance status or with a panel of susceptible and multi-resistant gastro-intestinal nematodes. Fecal egg counts were determined from several hours up to 14 days after treatment with Monepantel, benzimidazoles, levamisole, macrocyclic lactones or combinations of the latter three classes. The treatment of susceptible isolates with effective anthelmintics, either as single or combined applications caused a reduction of FEC to 0 within 3-4 days. The status of the resistant nematodes could be confirmed, as treatment with the affected classical anthelmintics never resulted in complete absence of parasite eggs in all samples analyzed. In the case of multi-resistant isolates, only Monepantel was able to stop egg excretion, while all other treatments resulted in only a partial reduction of FEC. The resistance status of the nematodes did not influence the rapid decline of egg counts after treatment with Monepantel.
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The effect of sheep breed, age, and gender on the pharmacokinetics and efficacy of Monepantel, an amino-acetonitrile derivative
Parasitology Research, 2009Co-Authors: Barry C. Hosking, Ronald Kaminsky, Heinz Sager, Wolfgang Seewald, Daniela Karadzovska, Jerome M. Giraudel, Jozef VercruysseAbstract:This analysis investigated the influence of breed and gender on the pharmacokinetics of Monepantel, and influence of breed, age, and gender on its efficacy against gastrointestinal nematodes of sheep. In a comparison of pharmacokinetic profiles from two studies, Merino lambs had significantly greater maximum concentrations of Monepantel and Monepantel sulfone, and faster times to reach these concentrations than Dorset cross lambs. Males had a statistically greater area under the curve (0–504 h) than females for Monepantel sulfone. The biological relevance of these relatively small differences is unclear because efficacy was not evaluated in these studies. For efficacy, a breed effect existed for some nematodes when sheep were treated at a sub-optimum dose (1.25 mg/kg). There were no gender effects between sheep infected with adult parasites and treated at 1.25 mg/kg but there were differences between females and males treated at this dose when infected with fourth-stage larvae of Haemonchus contortus , Teladorsagia circumcincta , Trichostrongylus colubriformis , and Cooperia curticei . There were no breed or gender differences for sheep treated at the recommended dose (2.5 mg/kg). There was a potential trend for declining efficacy with increasing animal age for fourth-stage Trichostrongylus axei . This analysis demonstrated that, similarly to what is observed with other anthelmintics, the pharmacokinetics and efficacy of Monepantel can vary with factors like breed, age, and gender. Identifying these covariates is important for understanding inter-individual variability in drug response. While further investigation is warranted, correctly treating sheep at the recommended dose of 2.5 mg/kg appears to mitigate any associated risk.
Wolfgang Seewald - One of the best experts on this subject based on the ideXlab platform.
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the comparative efficacy of abamectin Monepantel and an abamectin derquantel combination against fourth stage larvae of a macrocyclic lactone resistant teladorsagia spp isolate infecting sheep
Veterinary Parasitology, 2012Co-Authors: S D George, P A Stein, A J George, Barry C. Hosking, Peter F. Rolfe, Wolfgang SeewaldAbstract:Abstract Anthelmintic resistance by gastrointestinal nematodes of sheep continues to be an issue of global interest. While the recent introduction in some countries of one or two new anthelmintic classes (amino-acetonitrile derivatives [AAD] and spiroindoles [SI]) has been welcomed, it is important that there is no relaxation in parasite control and the management of drug resistance. Monepantel (an AAD) was the first new anthelmintic to be approved for use (New Zealand, 2009) and was followed a year later in the same country by a combination of derquantel (a SI) and abamectin. The present study determined the efficacy of the new anthelmintic products and abamectin against fourth-stage larvae of macrocyclic lactone-resistant Teladorsagia spp. in lambs. Efficacies were calculated by comparing post-mortem nematode burdens of treated animals with those of untreated control sheep, and were 98.5, 86.3 and 34.0% for Monepantel, abamectin/derquantel and abamectin, respectively. The nematode burdens of Monepantel- and abamectin/derquantel-treated sheep were significantly lower than those sheep treated with abamectin and the untreated controls. Similarly, the burden of the Monepantel group was significantly lower than that of the abamectin/derquantel group. These findings provide an opportunity to reinforce the recommendation that farmers and animal health advisors need to know the resistance status of nematode populations on subject farms to ensure effective control programs are designed and implemented. Such control programs should include an appropriate choice of anthelmintic(s), monitoring parasite burdens for correct timing of treatments, and pasture management to reduce larval challenge balanced with the maintenance of drug-susceptible populations in refugia.
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The comparative efficacy of abamectin, Monepantel and an abamectin/derquantel combination against fourth-stage larvae of a macrocyclic lactone-resistant Teladorsagia spp. isolate infecting sheep.
Veterinary Parasitology, 2012Co-Authors: S D George, P A Stein, A J George, B.c. Hosking, P.f. Rolfe, Wolfgang SeewaldAbstract:Anthelmintic resistance by gastrointestinal nematodes of sheep continues to be an issue of global interest. While the recent introduction in some countries of one or two new anthelmintic classes (amino-acetonitrile derivatives [AAD] and spiroindoles [SI]) has been welcomed, it is important that there is no relaxation in parasite control and the management of drug resistance. Monepantel (an AAD) was the first new anthelmintic to be approved for use (New Zealand, 2009) and was followed a year later in the same country by a combination of derquantel (a SI) and abamectin. The present study determined the efficacy of the new anthelmintic products and abamectin against fourth-stage larvae of macrocyclic lactone-resistant Teladorsagia spp. in lambs. Efficacies were calculated by comparing post-mortem nematode burdens of treated animals with those of untreated control sheep, and were 98.5, 86.3 and 34.0% for Monepantel, abamectin/derquantel and abamectin, respectively. The nematode burdens of Monepantel- and abamectin/derquantel-treated sheep were significantly lower than those sheep treated with abamectin and the untreated controls. Similarly, the burden of the Monepantel group was significantly lower than that of the abamectin/derquantel group. These findings provide an opportunity to reinforce the recommendation that farmers and animal health advisors need to know the resistance status of nematode populations on subject farms to ensure effective control programs are designed and implemented. Such control programs should include an appropriate choice of anthelmintic(s), monitoring parasite burdens for correct timing of treatments, and pasture management to reduce larval challenge balanced with the maintenance of drug-susceptible populations in refugia.
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Efficacy of Monepantel and anthelmintic combinations against multiple-resistant Haemonchus contortus in sheep, including characterisation of the nematode isolate.
Veterinary parasitology, 2011Co-Authors: K Baker, S D George, P A Stein, Wolfgang Seewald, P.f. Rolfe, B.c. HoskingAbstract:Abstract Three experiments defined the resistance profile of a population of Haemonchus contortus , which was shown to express multiple resistances to the benzimidazole, levamisole, macrocyclic lactone and salicylanilide anthelmintic classes when given as a registered combination. Study 1 was a faecal egg count reduction (FECR) test and the efficacies for the anthelmintics were Monepantel, 100%; abamectin + levamisole + oxfendazole, 40.0%; and abamectin + levamisole + oxfendazole + naphthalophos, 100%. No larvae were recovered from the post-treatment cultures for Monepantel or the 4-way treatment, and for the 3-way treatment the culture was 100% Haemonchus spp. Efficacies in Study 2 were calculated from mean post-mortem nematode burdens of H. contortus and were levamisole + oxfendazole, 3.1%; abamectin + levamisole + oxfendazole, 5.0%; ivermectin, 0.4%; moxidectin, 28.4% and closantel, 70.2%. Study 3 was also a FECR test that resulted in efficacies of 100% for Monepantel and 83.0% for a formulated 4-way combination of abamectin + levamisole + albendazole + closantel. Larvae recovered from the post-treatment culture for the combination-treated sheep were all Haemonchus spp. Multi-resistant parasites such as examined in these studies are a continuing challenge to be managed by farmers and their advisors. Control programs must be planned and well-managed, and should include on-farm testing for anthelmintic resistance, monitoring of nematode burdens (by FEC and larval culture) to determine appropriate treatment times and the management of pastures to reduce the overall parasite challenge. This should be in balance with the generation, use and maintenance of drug-susceptible nematode populations in refugia.
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Effect of route of administration on the efficacy and pharmacokinetics of an experimental formulation of the amino-acetonitrile derivative Monepantel in sheep.
Veterinary Record, 2010Co-Authors: B.c. Hosking, P A Stein, Wolfgang Seewald, Daniela Karadzovska, John K. House, Jerome M. GiraudelAbstract:The effect of the route of administration (oral, intraruminal and intra-abomasal) on the efficacy and pharmacokinetics of the new anthelmintic Monepantel in sheep was investigated. The target nematodes were fourth-stage Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis and Cooperia curticei. A clear difference in efficacy was identified between the routes of administration, although the difference did not consistently reach statistical significance; oral treatment was most effective, followed by intraruminal and then intra-abomasal administration. The same pattern was observed in the pharmacokinetic analysis, with lambs treated orally having more favourable exposure to Monepantel and its sulfone metabolite (albeit in all but one instance not significantly different) than the lambs treated by the other routes of administration, which were very similar for most parameters.
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The effect of sheep breed, age, and gender on the pharmacokinetics and efficacy of Monepantel, an amino-acetonitrile derivative
Parasitology Research, 2009Co-Authors: Barry C. Hosking, Ronald Kaminsky, Heinz Sager, Wolfgang Seewald, Daniela Karadzovska, Jerome M. Giraudel, Jozef VercruysseAbstract:This analysis investigated the influence of breed and gender on the pharmacokinetics of Monepantel, and influence of breed, age, and gender on its efficacy against gastrointestinal nematodes of sheep. In a comparison of pharmacokinetic profiles from two studies, Merino lambs had significantly greater maximum concentrations of Monepantel and Monepantel sulfone, and faster times to reach these concentrations than Dorset cross lambs. Males had a statistically greater area under the curve (0–504 h) than females for Monepantel sulfone. The biological relevance of these relatively small differences is unclear because efficacy was not evaluated in these studies. For efficacy, a breed effect existed for some nematodes when sheep were treated at a sub-optimum dose (1.25 mg/kg). There were no gender effects between sheep infected with adult parasites and treated at 1.25 mg/kg but there were differences between females and males treated at this dose when infected with fourth-stage larvae of Haemonchus contortus , Teladorsagia circumcincta , Trichostrongylus colubriformis , and Cooperia curticei . There were no breed or gender differences for sheep treated at the recommended dose (2.5 mg/kg). There was a potential trend for declining efficacy with increasing animal age for fourth-stage Trichostrongylus axei . This analysis demonstrated that, similarly to what is observed with other anthelmintics, the pharmacokinetics and efficacy of Monepantel can vary with factors like breed, age, and gender. Identifying these covariates is important for understanding inter-individual variability in drug response. While further investigation is warranted, correctly treating sheep at the recommended dose of 2.5 mg/kg appears to mitigate any associated risk.
