Fasciola hepatica: influence of gender and liver biotransformations on flukicide treatment efficacy of rats infested and cured with either clorsulon/ivermectin or triclabendazole

Coadministration of ivermectin and abamectin affects milk pharmacokinetics of the antiparasitic clorsulon in Assaf sheep

In veterinary field, drug exposure during milk production in dairy cattle is considered a major health problem which concerns dairy consumers. The induced expression of the ABC transporter G2 (ABCG2) in the mammary gland during lactation plays a significant role in the active secretion of many compounds into milk. The main objective of this study was to determine the involvement of ABCG2 in the secretion into milk of the antiparasitic clorsulon in sheep as well as the possible effect of the coadministration of model ABCG2 inhibitors such as macrocyclic lactones on this process. Cells transduced with the ovine variant of ABCG2 were used to carry out in vitro transepithelial transport assays in which we showed that clorsulon is a substrate of the ovine transporter. In addition, ivermectin and abamectin significantly inhibited clorsulon transport mediated by ovine ABCG2. In vivo interactions were studied in Assaf sheep after coadministration of clorsulon (in DMSO, 2 mg/kg, s.c.) with ivermectin (Ivomec®, 0.2 mg/kg, s.c.) or abamectin (in DMSO, 0.2 mg/kg, s.c.). After ivermectin and abamectin treatment, no relevant statistically significant differences in plasma levels of clorsulon were reported between the experimental groups since there were no differences in the area under the plasma concentration-curve (AUC) between clorsulon treatment alone and coadministration with macrocyclic lactones. With regard to milk, total amount of clorsulon, as percentage of dose excreted, did not show statistically significant differences when macrocyclic lactones were coadministered. However, the AUC for clorsulon significantly decreased (p < 0.05) after coadministration with ivermectin (15.15 ± 3.17 μg h/mL) and abamectin (15.30 ± 3.25 μg h/mL) compared to control group (20.73 ± 4.97 μg h/mL). Moreover, milk parameters such as half-life (T1/2) and mean residence time (MRT) were significantly lower (p < 0.05) after coadministration of macrocyclic lactones. This research shows that the milk pharmacokinetics of clorsulon is affected by the coadministration of ABCG2 inhibitors, reducing drug persistence in milk.

Role of the Abcg2 Transporter in Secretion into Milk of the Anthelmintic Clorsulon: Interaction with Ivermectin

Clorsulon is a benzenesulfonamide drug that is effective in treating helminthic zoonoses such as fascioliasis. When used in combination with the macrocyclic lactone ivermectin, it provides high broad-spectrum antiparasitic efficacy. The safety and efficacy of clorsulon should be studied by considering several factors such as drug-drug interactions mediated by ATP-binding cassette (ABC) transporters due to their potential effects on the pharmacokinetics and drug secretion into milk. The aim of this work was to determine the role of ABC transporter G2 (ABCG2) in clorsulon secretion into milk and the effect of ivermectin, a known ABCG2 inhibitor, on this process. Using in vitro transepithelial assays with cells transduced with murine Abcg2 and human ABCG2, we report that clorsulon was transported in vitro by both transporter variants and that ivermectin inhibited its transport mediated by murine Abcg2 and human ABCG2. Wild-type and Abcg2-/- lactating female mice were used to carry out in vivo assays. The milk concentration and the milk-to-plasma ratio were higher in wild-type mice than in Abcg2-/- mice after clorsulon administration, showing that clorsulon is actively secreted into milk by Abcg2. The interaction of ivermectin in this process was shown after the coadministration of clorsulon and ivermectin to wild-type and Abcg2-/- lactating female mice. Treatment with ivermectin had no effect on the plasma concentrations of clorsulon, but the milk concentrations and milk-to-plasma ratios of clorsulon decreased in comparison to those with treatment without ivermectin, only in wild-type animals. Consequently, the coadministration of clorsulon and ivermectin reduces clorsulon secretion into milk due to drug-drug interactions mediated by ABCG2.

Kangaroos and liver fluke: The role played in cross-species transmission and drug resistance

Australian livestock are challenged by liver fluke (Fasciola hepatica) in grazing regions endemic to the intermediate snail host. Liver fluke infests a wide range of herbivores including free-roaming wildlife such as kangaroos (Macropods). The role played by Macropods in cross-species transmission and as vectors for anthelmintic resistance is largely unknown. In Phase 1 of this study, liver fluke of Eastern grey kangaroo (Macropus giganteus Shaw, 1790) origin (Kangaroo isolate) were artificially infected in sheep to confirm establishment and cross-species transmission. In Phase 2, the efficacy of triclabendazole (TCBZ) was assessed in vivo against the Kangaroo isolate to identify any drug resistance. Forty (40) merino sheep were housed in pens and allocated to one of 4 groups (Groups 1-4). Groups 1 and 2 were artificially infected with a TCBZ resistant liver fluke isolate (Oberon) originating from sheep whilst Groups 3 and 4 were infected with the Kangaroo isolate (Phase 1). At 9 weeks post infection (wpi), sheep in Groups 2 and 4 were treated with 10 mg/kg TCBZ (Phase 2). Sheep were subsequently euthanased at 11 wpi to conduct total fluke counts (TFC) in the liver. Faecal samples were collected fortnightly to measure fluke egg counts and coproantigens. Individual blood samples were collected, concurrently with faecal sampling, to monitor haematocrit and plasma proteins levels. Liver fluke of kangaroo origin established to patent infections in sheep with similar establishment and pathogenicity to the Oberon isolate. TCBZ achieved an 86 % reduction in TFC (99.8 % - adult fluke, 0 % - immature fluke) in sheep with the Kangaroo isolate and a 28 % reduction in the Oberon isolate (37 % - adult, 0 % - immature fluke). An 89 % reduction in faecal coproantigens was observed in sheep with the Kangaroo isolate and no reduction in sheep with Oberon. This study confirmed cross-species transmission of liver fluke from a kangaroo to sheep. When cohabiting the livestock grazing environment, kangaroos may act as reservoirs for liver fluke and vectors for drug resistance within liver fluke endemic areas.

Evaluation of nitazoxanide treatment following triclabendazole failure in an outbreak of human fascioliasis in Upper Egypt

Background

Fascioliasis is a neglected zoonosis with major public health implications in humans. Although triclabendazole (TCBZ) is the drug of choice, there are records of TCBZ failure worldwide. TCBZ-resistant fascioliasis is treated with alternative approved drugs including nitazoxanide (NTZ), with varying levels of efficacy. Data on NTZ efficacy after TCBZ failure in Egypt is scarce. This study evaluated the efficacy of NTZ in cases of TCBZ failure during an outbreak of fascioliasis in Assiut governorate of Upper Egypt.

Methodology/Principal findings

This prospective study included 67 patients from the outpatient clinic in Manfalout locality of Assiut governorate with clinical manifestations of acute fascioliasis. These included high eosinophilia (> 6% eosinophils in peripheral blood), positive anti-Fasciola antibodies, and hepatic focal lesions (HFL) or ascites on abdominal ultrasound or computed tomography. All patients initially received TCBZ at recommended doses. Patients were followed up after 1 month to assess response. According to the responses, patients were categorized as non-responders and responders. The non-responders received a trial of NTZ and were re-assessed for response based on clinical manifestations, eosinophil count, and abdominal ultrasound. Patients not responding to NTZ received additional doses of TCBZ.

One month after initial TCBZ treatment, 37 patients responded well to TCBZ, while 30 patients failed to respond with persistence of fever, abdominal pain, high eosinophilia, and HFL. Most non-responders were male (56.7%); females predominated among TCBZ responders (62.2%). The mean age of the non-responders was relatively lower, at 20.57 ± 14.47 years (p = 0.004). Following NTZ therapy, HFL disappeared in 9/30 (30%) patients and eosinophil counts normalized in only 2 (6.7%) patients, indicating an overall efficacy of 36.6%. The remaining cases received additional doses of TCBZ with complete clinical, pathological, and radiological resolution.

Conclusions/Significance

Nitazoxanide was partially effective in TCBZ failure in acute human fascioliasis in Upper Egypt. Further studies with larger samples are highly encouraged and further research is urgently needed to find new therapeutic alternatives to TCBZ.

Fascioliasis is a neglected zoonosis with major public health implications in humans. Triclabendazole (TCBZ) is the drug of choice, but alternative approved drugs are necessary in cases of TCBZ failure. Nitazoxanide (NTZ) is an alternative used in such cases. However, the efficacy of NTZ in TCBZ-failure cases among patients in Egypt remains unclear. In this study, the efficacy of NTZ was evaluated in cases of TCBZ failure during an outbreak of human fascioliasis in Assiut governorate of Upper Egypt. This study enrolled 67 patients diagnosed with fascioliasis based on clinical, laboratory, and radiological findings. These patients were referred from the outpatient clinic in Manfalout locality of Assiut governorate in Egypt. All patients received TCBZ at recommended doses as initial treatment. Those failing to respond were treated with NTZ at standard doses; following therapy, lesions in the liver and high eosinophil counts were resolved in 30% and 6.7% patients, respectively, indicating an overall efficacy of 36.6%. Therefore, in this outbreak of human fascioliasis in Upper Egypt, NTZ was found to be partially effective in cases with TCBZ failure.

Evaluation of five treatments to control intestinal parasites in sheep in Ayapango, state of Mexico

AIM

Intestinal parasites are one of the most common problems in sheep production systems. However, the strategies used to eliminate these parasites have not yielded satisfactory results. Therefore, the aim of this study was to determine the effect of five anthelmintics (with different active ingredients) on the parasite load in sheep.

MATERIALS AND METHODS

In this study, 107 Rambouillet breed sheep were randomly assigned to five groups. Next, fecal samples were taken directly from the rectum and sent to the laboratory for analysis. We then dewormed each group of sheep using different anthelmintic products: Ivermectin 1%/clorsulon 10%, levamisole 12%, closantel sodium 5%, ivermectin 10%, and closantel 5%/albendazole 3.75% with a dosage corresponding to each sheep. At 15 days post-treatment, we took fecal samples and performed a coproparasitoscopic study, using the Faust flotation technique to assess the presence or absence of parasite eggs and the McMaster technique to quantify eggs.

RESULTS

Ivermectin/clorsulon was more effective in eliminating parasites than other anthelmintics used, especially in Haemonchus spp.

CONCLUSION

The results of this study indicate that using ivermectin/clorsulon decreases the number of eggs in feces and is one alternative in controlling parasites in sheep, leading to a reduction in the incidence of health problems, and consequently, improved productivity.

Separation and characterization of synthetic impurities of triclabendazole by reversed-phase high-performance liquid chromatography/electrospray ionization mass spectrometry

A simple high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) method for the separation and characterization of impurities in the synthesis of triclabendazole has been developed. The analytical separation was achieved on a reversed-phase C18 column using acetonitrile and water (60:40, v/v) as mobile solvent at a flow-rate of 1.0 ml/min at 25 degrees C, and an UV detection at 230 nm. The on-line HPLC/ESI-MSn examinations were performed using ion trap analyzer with extraction ion chromatography (EIC) technique in positive or negative ion modes. The semi-preparative separation was performed with a reversed-phase column using methanol and water (75:25, v/v) as mobile solvent at a flow-rate of 4 ml/min at 25 degrees C, and an UV detection at 230 nm. Thus, two impurities were detected and identified as 5-chloro-6-(2,3,4-trichlorophenoxy)-2-methylsulfanyl-1H-benzoimidazole and 5-chloro-6-(2,3-dichlorophenoxy)-1-methyl-2-methylsulfanyl-1H-benzoimidazole. Meanwhile, some intermediates of impurity-1 in multi-step synthetic reactions, were tracked. Structural elucidation by 1D and 2D NMR and ESI-MSn was discussed.