BACKGROUND: During the last two decades, anthelmintic drugs have been increasingly applied against gastrointestinal parasites of sheep in Iran. OBJECTIVES: For this purpose, drug resistance to albendazole (Alb) and fenbendazole (Feb) in gastrointestinal nematodes in sheep of Saqez multiplicity was assessed. METHODS: In in-vivo experiment, a total number of 90 sheep in three groups (30 sheep/group) with EPG≤150 were examined for nematode resistance to Alb and Feb. They were treated with Alb and Feb or untreated (as a control group). RESULTS: There was significant difference between Alb and Feb treated groups and control group. The EPG in Alb, Feb and control groups was 59.8±1.93, 18.8±1.258 and 204.07±4.81, respectively. There was drug resistance against Alb in compassion with control group (R=71%). There was suspicion drug resistance for Feb in comparison with control group (R=90.66%). CONCLUSIONS: From the results of the present study, it was concluded that there was absolute and suspected drug resistance against Alb and Feb in sheep of Saqez municipality, Iran, respectively.

Introduction: Albendazole is used to treat endoparasitic diseases in animals and humans. After oral administration, it is quickly oxidised into its pharmacologically active metabolite albendazole sulfoxide and then to sulfone. However, it is not clear which compound is responsible for toxic effects towards mammalian cells. Material and Methods: The model systems comprised cultures of isolated rat hepatocytes, two hepatoma cell lines (FaO, HepG2), and non-hepatic Balb/c 3T3 line. Cells were exposed for 24, 48, and 72 h to eight concentrations of albendazole ranging from 0.05 to 100 μg/mL. At all three time points cytotoxic effects were assessed by MTT assay and metabolites in the culture media were determined by LC-MS/MS analysis. Results: The effective concentrations EC50-72h showed that Balb/c 3T3 cells were the most sensitive to albendazole (0.2 ±0.1 μg/mL) followed by FaO (1.0 ±0.4 μg/mL), and HepG2 (6.4 ±0.1 μg/mL). In the case of isolated hepatocytes this value could not be attained up to the highest concentration used. Chemical analysis revealed that the concentrations of albendazole in hepatocytes and HepG2 and FaO culture media gradually decreased with incubation time, while the concentrations of its metabolites increased. The metabolism in isolated hepatocytes was dozens of times greater than in HepG2 and FaO cells. Two metabolites (albendazole sulfoxide, albendazole sulfone) were detected in isolated hepatocytes and HepG2 culture medium, one (albendazole sulfoxide) in FaO culture medium and none in Balb/c 3T3. Conclusion: The obtained data indicate that metabolism of albendazole leads to its detoxification. The lower cytotoxic potential of metabolites was confirmed in the independent experiments in this study.

The control of gastrointestinal nematodes (GINs) in small ruminants is principally dependent on anthelmintic therapy, which encounters the rising problem of anthelmintic resistance (AR) development. Veterinarians reported anthelmintic failure in several sheep farms in Arbat District, Sulaymaniyah, northern Iraq, which called for a systematic study about the efficacy of three commonly used drugs: albendazole, ivermectin, and levamisole.

Introduction: The cytotoxicity of anthelmintic agent, albendazole (ABZ) and its two major metabolites, sulfoxide (ABZSO) and sulfone (ABZ-SO₂), on non-hepatic Balb/c 3T3 line, two hepatoma cell lines (FaO, HepG2), and isolated rat hepatocytes was investigated. Material and Methods: Cell cultures were exposed for 24, 48, and 72 h to eight concentrations of the compounds ranging from 0.05 to 100 μg/mL (ABZ) and from 0.78 to 100 μg/mL (ABZ-SO and ABZ-SO₂). Three different assays were applied in which various biochemical endpoints were assessed: lysosomal activity - neutral red uptake (NRU) assay, proliferation - total protein contents (TPC) assay and lactate dehydrogenase (LDH) leakage assay. Results: The most toxic was albendazole whose EC₅₀ values calculated from the concentration effect curves ranged from 0.2 to 0.5 μg/mL (Balb/c 3T3) and from 0.4 to 73.3 μg/mL (HepG2). Rat hepatoma line and isolated rat hepatocytes were less sensitive to the impact of ABZ. Toxic action expressed as EC₅₀ was recorded after 72 h exposure only in LDH release assay at 0.8 μg/mL and 9.7 μg/mL respectively. The toxicity of metabolites was much lower. The most sensitive to ABZ-SO were fibroblasts and EC₅₀₋₇₂ₕ values were similar in all three assays used, i.e. NRU (14.1 μg/mL), TPC (15.8 μg/mL), and LDH (20.9 μg/mL). In the case of ABZ-SO₂ the mean effective concentrations were the highest, and could be reached only in one LDH assay. These values (μg/mL) were as follows: 65.3 (FaO), 65.4 (HepG2), 75.8 (hepatocytes), and 77.4 (Balb/c 3T3). Conclusion: The differences in in vitro toxicity of albendazole depend on metabolic ability of the cellular models. Primary cultured rat hepatocytes represent a valuable tool to study the impact of biotransformation on the cytotoxicity of drugs.

Introduction: The cytotoxicity of anthelmintic agent, albendazole (ABZ) and its two major metabolites, sulfoxide (ABZSO) and sulfone (ABZ-SO2), on non-hepatic Balb/c 3T3 line, two hepatoma cell lines (FaO, HepG2), and isolated rat hepatocytes was investigated. Material and Methods: Cell cultures were exposed for 24, 48, and 72 h to eight concentrations of the compounds ranging from 0.05 to 100 μg/mL (ABZ) and from 0.78 to 100 μg/mL (ABZ-SO and ABZ-SO2). Three different assays were applied in which various biochemical endpoints were assessed: lysosomal activity - neutral red uptake (NRU) assay, proliferation - total protein contents (TPC) assay and lactate dehydrogenase (LDH) leakage assay. Results: The most toxic was albendazole whose EC50 values calculated from the concentration effect curves ranged from 0.2 to 0.5 μg/mL (Balb/c 3T3 ) and from 0.4 to 73.3 μg/mL (HepG2). Rat hepatoma line and isolated rat hepatocytes were less sensitive to the impact of ABZ. Toxic action expressed as EC50 was recorded after 72 h exposure only in LDH release assay at 0.8 μg/mL and 9.7 μg/mL respectively. The toxicity of metabolites was much lower. The most sensitive to ABZ-SO were fibroblasts and EC50-72h values were similar in all three assays used, i.e. NRU (14.1 μg/mL), TPC (15.8 μg/mL), and LDH (20.9 μg/mL). In the case of ABZ-SO2 the mean effective concentrations were the highest, and could be reached only in one LDH assay. These values (μg/mL) were as follows: 65.3 (FaO), 65.4 (HepG2), 75.8 (hepatocytes), and 77.4 (Balb/c 3T3). Conclusion: The differences in in vitro toxicity of albendazole depend on metabolic ability of the cellular models. Primary cultured rat hepatocytes represent a valuable tool to study the impact of biotransformation on the cytotoxicity of drugs.

Faecal samples of 264 sheep from 4 different sheep farms belonging to three different districts of Karnataka were screened to note the incidence of gastrointestinal nematodes. It was found that 93% of the sheep harboured strongyle infection. The faecal egg counts were found to be light to moderate. The in vitro egg hatch assay was employed to assess the resistance of strongyles in 4 sheep farms. The ED50 value for albendazole ranged between 2.5μg/ml to 6.9 μg/ ml which indicated the resistance of the gastrointestinal nematodes. All the samples were also subjected to another in vitro test, viz., larval development assay. The values ranged between 3-2μg to 4.2μg / ml which also indicated the development of resistance to albendazole. Larval paralysis assay confirmed the development of resistance to albendazole. 

There are limited data on the efficacy of antiparasitic treatments and husbandry methods to control nematode infections in captive populations of African green monkeys (AGMs), Chlorocebus sabaeus. In faecal egg count (FEC) tests, 10 of the 11 (91%) adult male AGMs captured from the large feral population on the island of St Kitts had evidence of nematode infections, mostly Capillaria (8/11, 73%), Trichuris trichiura (7/11, 64%) and strongylid species (7/11, 64%) specifically (hookworm and Trichostrongylus, 50/50), but also Strongyloides fuelleborni (1/11, 9%). When kept in individual cages with cleaning and feeding regimens to prevent reinfections and treated concurrently with ivermectin (300 µg/kg, given subcutaneously) and albendazole (10 mg/kg, given orally) daily for 3 days, 60% (6/10) of the AGMs were negative at a follow-up FEC at 3 months and by FEC and necropsy at the end of the study 5-8 months later. One monkey appeared to have been reinfected with T. trichiura after being negative by FEC at 3 months post-treatment. Four AGMs were positive for T. trichiura at the 3 month FEC follow-up but were negative at the end of the study after one further treatment regimen. Although initially being cleared of Capillaria following treatment, three AGMs were found to be infected at the end of the study. The ivermectin and albendazole treatment regimen coupled with good husbandry practices to prevent reinfections effectively controlled nematode infections in captive AGMs.

Albendazole, administered orally at a dose rate of 25 mg/kg of body weight to presumed pregnant cows or heifers on days 21, 31, 41, 51, and 61 of gestation, did not induce toxicosis in embryos or fetuses, and all calves born were structurally normal. Albendazole administration at a rate of 25 mg/kg to cows at 7 and/or 14 days of gestation decreased the apparent conception rate (ie, embryolethality), but did not have a teratogenic effect. Apparent embryolethality was greater in cows administered 25 mg/ kg only on day 14, compared with those administered the drug only on day 7. Single dosage of 25 mg/kg given in the final 3 months of gestation did not induce abortion. There were no adverse effects of albendazole at a dosage of 10 or 15 mg/kg on developing embryos or fetuses when administered to presumed pregnant cows at various times in early gestation.

Studies were undertaken to determine the efficacy of milbemycin oxime against the enteric adult stages of Trichinella spiralis and of albendazole against the muscle stage larvae in experimentally infected dogs and cats. Specific-pathogen-free Beagle pups (n = 6) and domestic shorthair kittens (n = 6) were inoculated with 7,500 first-stage larvae of Trichinella spiralis. Physical examination (including collection of blood and fecal samples) was performed weekly. During the first week after inoculation, all animals had mild gastrointestinal tract disturbances, but stages of T. spiralis were not observed in the feces. Beginning on postinoculation day (PID) 10, 3 pups and 3 kittens were treated with milbemycin oxime (1.25 mg/kg of body weight, PO, q 12 h) for 10 days. Muscle biopsy specimens were taken from dogs and cats on PID 26 and 29, respectively. Mean numbers of larvae per gram of muscle were 30.3 in the control and 37.7 in the treated dogs. Mean numbers of larvae per gram of muscle in the control and treated cats were 318.7 and 89.3, respectively. Two dogs and 2 cats were removed from the study at that time. The remaining animals, 2 each of the control and milbemycin oxime-treated animals, were given albendazole (50 mg/kg, PO, q 12 h) for 7 days starting at PID 31 and 34 in dogs and cats, respectively. Muscle biopsy specimens were again taken at PID 46 and 49, for dogs and cats, respectively; mean numbers of larvae recovered from muscle were 0.6 for dogs and 13.5 for cats.