Oxfendazole Research Articles

Preparation, characterization and application of a new stir bar sorptive extraction based on poly(vinylphthalimide-co-N,N′-methylenebisacrylamide) monolith

In this study, a new stir bar sorptive extraction (SBSE) coating based on poly(vinylphthalimide-co-N,N'-methylenebisacrylamide) monolith (SBSE-VPMB) was prepared. The influences of the contents of monomer in polymerization mixture and the percentage of porogen solvent on the extraction performance were investigated thoroughly. Several characteristic techniques, such as elemental analysis, scanning electron microscopy, mercury intrusion porosimetry and infrared spectroscopy, were used to characterize the monolithic material. The analysis of oxfendazole (OFZ) and mebendazole (MBZ) in milk and honey samples by the combination of SBSE with HPLC with diode array detection was selected as paradigms for the practical evaluation of the new coating. Under the optimized extraction conditions, the limits of detection (S/N=3) for OFZ and MBZ were 0.23-0.60 μg/L in milk and 0.24-1.08 μg/L in honey, respectively. The method also showed good linearity, repeatability, high feasibility and acceptable recoveries for real samples. At the same time, the extraction performance and the distribution coefficients (K(VPMB/W)) of OFZ and MBZ on SBSE-VPMB were compared with other SBSEs based on porous monoliths and commercial SBSE.

DETERMINATION OF ALBENDAZOLE, FENBENDAZOLE, AND THEIR METABOLITES IN MOUSE PLASMA BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY USING FLUORESCENCE AND ULTRAVIOLET DETECTION

A rapid and reliable high performance liquid chromatographic (HPLC) method has been developed and validated for the determination of albendazole (ABZ), albendazole sulfoxide (ABZSO), albendazole sulfone (ABZSO2); fenbendazole (FBZ), fenbendazole sulfoxide (FBZSO), and fenbendazole sulfone (FBZSO2) in mouse plasma. The mouse plasma was made alkaline with potassium carbonate and extracted with ethylacetate. The extracts were evaporated, reconstituted in mobile phase, and analyzed by HPLC. The chromatography was carried out on a reversed-phase column using acetonitrile-methanol-buffer as the mobile phase. The fenbendazole and its metabolites were detected by using UV detector set at the wavelength of 290 nm. The albendazole and its metabolites were detected by a fluorescence detector with excitation and emission wavelengths of 290 and 330 nm, respectively. The average recoveries of ABZ, ABZSO, and ABZSO2 from fortified control plasma samples were 95, 82, and 92%, respectively. Similarly, the average recoveries of FBZ, FBZSO, and FBZSO2 were 64, 90, and 94%, respectively. The average CVs were ≤15% for all of the compounds. The method was applied to incurred mouse plasma samples to determine ABZ, FBZ, and their metabolites.

Immunohistochemical analyses at the late stage of tumor promotion by oxfendazole in a rat hepatocarcinogenesis model

The present study was performed to characterize immunohistochemically the expression levels of molecules related to not only xenobiotic and antioxidant functions but also cell proliferation and apoptosis in neoplastic lesions induced by the benzimidazole anthelmintic, oxfendazole (OX), at the late stage of its tumor promotion in a rat hepatocarcinogenesis model. Male F344 rats were initiated with an intraperitoneal injection of 200mg/kg N-diethylnitrosamine, and 2weeks later they were fed a diet containing 0% (basal diet) or 0.05% OX for 26weeks. All animals were subjected to a two-thirds partial hepatectomy at week 3 and killed at week 28. Histopathologically, OX increased the incidence and multiplicity of altered foci (4.0- and 3.6-fold, respectively) and hepatocellular adenomas (HCAs) (3.0- and 5.5-fold, respectively). OX treatment induced 5.2- and 5.6-fold increases in the number of proliferating cell nuclear antigen (PCNA)-positive cells and single-stranded DNA (ssDNA)-positive cells in HCAs compared with the surrounding tissue, respectively. Staining for the cell cycle regulators P21 and C/EBPα and the AhR-regulated CYP1A1 molecules decreased but increased reactivity of the Nrf2-regulated, detoxifing/antioxidant molecules aldo-keto reductase 7 (AKR7) and glutathione peroxidase 2 (GPX2) were also seen in HCAs compared with the surrounding hepatocytes. These results suggest that dysregulation of cell proliferation and apoptosis and escape from oxidative stress elicited by OX treatment play an important role in OX-induced hepatocarcinogenesis in rats.

Preliminary studies on the effect of fenbendazole and oxfendazole on Taenia saginata cysticerci in calves.

Summary Oxfendazole given orally to calves in doses of 50 mg./kg. or 100 mg./kg. body weight and fenbendazole at 100 mg./kg. or 4 × 50 mg./kg. had no lethal effect on 10-week-old cysticerci of Taenia saginata. Zusammenfassung Orientierende Untersuchungen uber die Wirkung von Fenbendazol und Oxfendazol auf Cysticercus bovis beim Kalb Fenbendazol in Dosierungen von 100 mg/kg und 4 × 50 mg/kg sowie Oxfendazol in Dosierungen von 50 mg/kg und 100 mg/kg erwiesen sich als unwirksam gegen 10 Wochen alte Rinderfinnen.

Evaluation of Oxfendazole, Praziquantel and Albendazole against Cystic Echinococcosis: A Randomized Clinical Trial in Naturally Infected Sheep

BackgroundCystic Echinococosis (CE) is a zoonotic disease caused by larval stage Echinococcus granulosus. We determined the effects of high dose of Oxfendazole (OXF), combination Oxfendazole/Praziquantel (PZQ), and combination Albendazole (ABZ)/Praziquantel against CE in sheep.Methodology/Principal FindingsA randomized placebo-controlled trial was carried out on 118 randomly selected ewes. They were randomly assigned to one of the following groups: 1) placebo; 2) OXF 60 mg/Kg of body weight (BW) weekly for four weeks; 3) ABZ 30 mg/Kg BW + PZQ 40 mg/Kg BW weekly for 6 weeks, and 4) OXF 30 mg/Kg BW+ PZQ 40 mg/Kg BW biweekly for 3 administrations (6 weeks). Percent protoscolex (PSC) viability was evaluated using a 0.1% aqueous eosin vital stain for each cyst. “Noninfective” sheep were those that had no viable PSCs; “low-medium infective” were those that had 1% to 60% PSC viability; and “high infective” were those with more than 60% PSC viability. We evaluated 92 of the 118 sheep. ABZ/PZQ led the lowest PSC viability for lung cysts (12.7%), while OXF/PZQ did so for liver cysts (13.5%). The percentage of either “noninfective” or “low-medium infective” sheep was 90%, 93.8% and 88.9% for OXF, ABZ/PZQ and OXF/PZQ group as compared to 50% “noninfective” or “low-medium infective” for placebo. After performing all necropsies, CE prevalence in the flock of sheep was 95.7% (88/92) with a total number of 1094 cysts (12.4 cysts/animal). On average, the two-drug-combination groups resulted pulmonary cysts that were 6 mm smaller and hepatic cysts that were 4.2 mm smaller than placebo (p<0.05).Conclusions/SignificanceWe demonstrate that Oxfendazole at 60 mg, combination Oxfendazole/Praziquantel and combination Albendazole/Praziquantel are successful schemas that can be added to control measures in animals and merits further study for the treatment of animal CE. Further investigations on different schedules of monotherapy or combined chemotherapy are needed, as well as studies to evaluate the safety and efficacy of Oxfendazole in humans.

Changes to oxfendazole chiral kinetics and anthelmintic efficacy induced by piperonyl butoxide in horses

The study of novel pharmacological strategies to control parasitism in horses is required since many parasite species have developed resistance to anthelmintic drugs. To evaluate the effects of piperonyl butoxide (PB) (a metabolic inhibitor) on the plasma availability and enantiomeric behaviour of oxfendazole (OFZ) given orally to horses, and to compare the clinical efficacy of OFZ given either alone or co-administered with PB in naturally parasitised horses. Fifteen naturally parasitised crossbred male ponies were allocated into 3 groups (n = 5) and treated orally as follows: Group I (control) received distilled water as placebo; Group II was dosed with OFZ (10 mg/kg bwt); and Group III was treated with OFZ (10 mg/kg bwt) co-administered with PB (63 mg/kg bwt). Jugular blood samples were obtained over 120 h post treatment. Three weeks after treatments, all experimental horses were subjected to euthanasia. The observed maximum plasma concentration (Cmax) and area under the concentration vs. time curve (AUC) values for OFZ increased 3- and 5-fold, respectively, in the presence of PB. The plasma concentration profiles of fenbendazole (FBZ), a metabolite generated from OFZ, were significantly lower after the treatment with OFZ alone (AUC = 0.8 microg x h/ml) compared to those obtained after the OFZ + PB treatment (AUC = 2.7 microg x h/ml). The enhanced pharmacokinetic profiles correlated with increased anthelmintic efficacy. The combination OFZ + PB showed 100% efficacy against mature nematode parasites. The efficacy against cyathostome L3 larvae increased from 94% (Group II) to 98.7% (Group III). Consistently, the number of L4 larvae recovered from OFZ + PB treated horses (Group III) (n = 146) was significantly lower (P<0.05) than that recovered from Group II (n = 1397). The use of PB as a metabolic inhibitor may be useful to enhance OFZ activity against mature and migrating larvae of different parasite species in horses. Metabolic inhibitors may be used to enhance the activity of benzimidazole anthelmintics and extend the effective lifespan of benzimidazole drugs in the face of increasing resistance.

Antioxidant enzymatically modified isoquercitrin or melatonin supplementation reduces oxidative stress-mediated hepatocellular tumor promotion of oxfendazole in rats

To clarify whether enzymatically modified isoquercitrin (EMIQ) or melatonin (MLT) supplementation reduces oxidative stress-mediated hepatocellular tumor-promoting effect of oxfendazole (OX), a benzimidazole anthelmintic, male rats were administered a single intraperitoneal injection of N-diethylnitrosamine (DEN) and were fed a diet containing OX (500 ppm) for 10 weeks with or without EMIQ (2,000 ppm) or MLT (100 ppm) in the drinking water after DEN initiation. One week after the commencement of the administration of OX, rats were subjected to two-thirds of partial hepatectomy. The number of GST-P-positive foci promoted by OX was significantly inhibited by the combined antioxidant EMIQ or MLT administration, and the area of GST-P-positive foci was inhibited by the administration of MLT. Real-time RT-PCR analysis revealed decreases in mRNA expression levels of cytochrome P450, family 2, subfamily b, polypeptide 2 (Cyp2b2) and malic enzyme 1 (Me1) in the DEN-OX-EMIQ and DEN-OX-MLT groups and decreases in mRNA expression levels of Cyp1a1 and aldo-keto reductase family 7, member A3 (Akr7a3) in the DEN-OX-MLT group compared to those in the DEN-OX group. In in vitro ROS production assay, inhibited production of NADPH-dependent ROS was observed by the treatment with EMIQ or MLT. These results suggest that coadministration of EMIQ or MLT suppresses the hepatocellular tumor-promoting activity of OX in rats through the decrease in ROS production by the activation of CYPs.

Comparative assessment of albendazole and triclabendazole ovicidal activity on Fasciola hepatica eggs

The benzimidazole compounds albendazole (ABZ) and triclabendazole (TCBZ) are both effective against Fasciola hepatica, although ABZ is only effective against adult flukes. Additionally, ABZ is a broad-spectrum nematodicidal compound with well-known ovicidal activity. However, no data on the ovicidal effect of TCBZ against F. hepatica eggs are available. The work reported here evaluated the comparative ovicidal effect of ABZ, TCBZ and their sulphoxide metabolites on F. hepatica eggs recovered from bile of sheep artificially infected with either a TCBZ-susceptible (Cullompton) or a TCBZ-resistant (Sligo) isolate of F. hepatica. Additionally, the effects of different non-flukicidal methylcarbamate benzimidazole compounds on the hatching of F. hepatica eggs were evaluated. Eggs (500 eggs/mL, n = 4) were incubated for 12 h either with TCBZ, TCBZ sulphoxide (TCBZ.SO), ABZ (5, 10 and 20 nmol/mL) or without drug (untreated control) (Experiment 1). Additionally, the effect of TCBZ and TCBZ.SO (5 nmol/mL) on egg hatchability was examined after a long (15 days) drug exposure (Experiment 2). Furthermore, the ovicidal effect of ABZ and ABZ.SO at different concentrations (5, 1, 0.5, 0.1and 0.05 nmol/mL) (Experiment 3), and the effect of fenbendazole (FBZ), oxfendazole (OFZ), mebendazole (MBZ), flubendazole (FLBZ) (5 nmol/mL) and reduced-FLBZ (R-FLBZ) (2 μg/mL) on fluke eggs, were evaluated after a 12-h exposure (Experiment 4). Egg hatch was assessed by direct microscopic observation after incubation at 25 °C for 15 days. TCBZ and TCBZ.SO did not affect egg hatch after a 12-h incubation. A similar result was obtained after a much longer drug exposure (15 days) (Experiment 1 and 2). However, a significant ( P < 0.05) inhibition of egg hatch was observed in ABZ- and ABZ.SO-incubated eggs (Experiments 1 and 3). Additionally, the non-flukicidal compounds (Experiment 4) affected egg hatchability, particularly FLBZ and R-FLBZ. In conclusion, ABZ and ABZ.SO had a clear inhibitory effect on egg development of F. hepatica. However, the most extensively used flukicidal compound, TCBZ, and its main sulphoxide metabolite, did not affect egg hatch, even in TCBZ-susceptible flukes.

Evaluation of Nitazoxanide and Oxfendazole Efficacy against Cystic Echinococcosis in Naturally Infected Sheep

Cystic echinococosis (CE) is a public health problem caused by Echinococcus granulosus. We aimed to determine the efficacy of nitazoxanide (NTZ) and oxfendazole (OXF) against CE in naturally infected sheep. A total of 151 ewes were assigned to the following groups: 15 mg/kg of NTZ weekly for five weeks (NTZ5); two rounds of 15 mg/ kg of NTZ a day for five days (NTZ5x2) two weeks apart; 30 mg/kg of OXF a week for 11 weeks (OXF11); 30 mg/kg of OXF plus 15 mg/kg of NTZ a week for 11 weeks (OXF/NTZ); and the control group. OXF11 and OXF/NTZ decreased the number of fertile cysts, increased the number of degenerated cysts, and were more efficacious (49.6-61.2%) against lung cysts and liver cysts (91.8-100%) than any other treatment group. OXF might be an additional strategy for control programs and an optional treatment of human CE after it is licensed.

Taenia solium porcine cysticercosis: Viability of cysticerci and persistency of antibodies and cysticercal antigens after treatment with oxfendazole

The aim of this study was to assess the effect of treating Taenia solium infected pigs with oxfendazole (OFZ) on viability and clearance of cysticerci and the corresponding persistence of specific antibody isotypes (IgG total, IgG1, IgG2 and IgA) and circulating cysticercal antigen (CCA). Antibody isotypes and CCA responses were measured by antibody-ELISA (Ab-ELISA) and antigen ELISA (Ag-ELISA), respectively. Correlations were made between antibodies, CCA and the total number of cysticerci enumerated at necropsy. Forty pigs with cysticercosis were randomly allocated into two groups: Treatment group ( n = 20) was treated with OFZ at 30 mg/kg orally while the treatment control group ( n = 20) was not treated. Five uninfected pigs served as negative controls. Pigs were killed at 1, 4, 8 and 26 weeks post-treatment (wkpt). Overall, the mean total cyst count in treated pigs was 2904 ± 5397 (mean ± S.D.) while in the controls it was 6235 ± 6705. Mean cyst viability was 5 ± 11% (mean ± S.D.) and 97 ± 4% in treated and control pigs, respectively. Results showed that OFZ killed muscular cysticerci over a period of 4 weeks but failed to kill cerebral cysticerci. Antibodies, CCA responses and clearance of dead cysts from the meat, depended on the cyst intensity of individual pigs at time of treatment since both antibody and CCA correlated with intensity of cysticerci at necropsy ( r = 0.441, P = 0.005; r = 0.654, P < 0.001), respectively. IgG1 responses were the best indicator of treatment efficacy because they were predominant in both infected treated and control pigs and disappeared early after treatment. Both Ab/Ag-ELISA failed to detect cysts in the brain. Though dead cysticerci took some time (26 wkpt) to clear from the meat, treatment of porcine cysticercosis with OFZ should, in combination with other intervention measures be considered as an important, cost-effective measure in the control of taeniosis/cysticercosis.

Involvement of oxidative stress in hepatocellular tumor-promoting activity of oxfendazole in rats

The tumor-promoting effects of oxfendazole (OX), a benzimidazole anthelmintic, were investigated using a medium-term rat hepatocarcinogenesis model. Six-week-old male F344 rats received an intraperitoneal injection of N-diethylnitrosamine (DEN) and were given a powdered diet containing 0 or 500 ppm OX for 6 weeks from 2 weeks after DEN treatment. All animals were subjected to two-thirds partial hepatectomy 1 week after OX treatment. The numbers and areas of glutathione S-transferase placental form (GST-P)-positive foci were significantly increased in the livers of rats treated with OX, with concomitantly increased cell proliferation, compared with those in the livers of the DEN alone group. Quantitative real-time RT-PCR analysis revealed that OX induced not only mRNA expression of phase I enzymes Cyp1a1, Cyp1a2, but also Nrf2-regulated phase II enzymes such as Gpx2, Nqo1, Yc2, Akr7a3 and Gstm1, presumably due to an adaptive response against OX-induced oxidative stress. Reactive oxygen species production increased in microsomes isolated from the livers of OX-treated rats. Furthermore, OX enhanced oxidative DNA damage (as assessed by 8-hydroxydeoxyguanosine; 8-OHdG) and lipid peroxidation (as assessed by thiobarbituric acid-reactive substances; TBARS). These results suggest that administration of OX at a high dose and for a long term enhances oxidative stress responses, which may contribute to its tumor-promoting potential in rats.

Comparative plasma disposition of fenbendazole, oxfendazole and albendazole in dogs

The plasma disposition of fenbendazole (FBZ), oxfendazole (OFZ) and albendazole (ABZ); and the enantiospecific disposition of OFZ, and ABZSO produced were investigated following an oral administration (50 mg/kg) in dogs. Blood samples were collected from 1 to 120 h post-administration. The plasma samples were analysed by high performance liquid chromatography (HPLC). The plasma concentration of FBZ, OFZ, ABZ and their metabolites were significantly different from each other and depended on the drug administered. The sulphone metabolite (FBZSO 2) of FBZ was not detected in any plasma samples and the parent molecule ABZ did not reach quantifiable concentrations following FBZ and ABZ administration, respectively. OFZ and its sulphone metabolite attained a significantly higher plasma concentration and remained much longer in plasma compared with FBZ and ABZ and their respective metabolites. The maximum plasma concentrations ( C max), area under the concentration time curve (AUC) and mean residence time (MRT) of parent OFZ were more than 30, 68 and 2 times those of FBZ, respectively. The same parameters for ABZSO were also significantly greater than those of FBZSO. The ratio for total AUCs of both the parent drug and the metabolites were 1:42:7 for following FBZ, OFZ and ABZ administration, respectively. The enantiomers were never in racemic proportions and (+) enantiomers of both OFZ and ABZSO were predominant in plasma. The AUC of (+) enantiomers of OFZ and ABZSO was, respectively more than three and seven times larger than that of (−) enantiomers of both molecules. It is concluded that the plasma concentration of OFZ was substantially greater compared with FBZ and ABZ. The data on the pharmacokinetic profile of OFZ presented here may contribute to evaluate its potential as an anthelmintic drug for parasite control in dogs.

Gene expression analyses of the liver in rats treated with oxfendazole

The effect of oxfendazole (OX), a benzimidazole anthelmintic, on hepatic gene expression was investigated in the liver of rats as a preliminary study to elucidate the possible mechanism of its non-genotoxic hepatocarcinogenesis. The liver from a male F344/N rat given a diet containing 500 ppm of OX for 3 weeks was examined by global gene expression analysis in comparison with an untreated rat. Microarray analysis revealed that phase I and phase II detoxifying enzymes were up-regulated in an OX-treated rat. In addition to these genes, the expressions of several upregulated genes related to xenobiotic metabolism and oxidative stress [e.g. Cyp1a1; NAD(P)H dehydrogenase, quinone 1 (Nqo1); glutathione peroxidase 2 (Gpx2); glutathione S-transferase Yc2 subunit (Yc2)], were confirmed by real-time reverse transcription polymerase chain reaction (RT-PCR). Furthermore, rats were administered 500 or 1,000 ppm of OX for 9 weeks, and the effect of OX on oxidative stress responses was evaluated by real-time RT-PCR along with conventional toxicological assays, including lipid peroxidation (thiobarbituric acid-reactive substance; TBARS). A longer treatment period and/or a higher dose of OX tended to increase the gene expressions of not only phase I (Cyp1a1 and Cyp1a2) but also phase II (Nqo1, Gpx2, Yc2, and Akr7a3) drug metabolizing enzymes. Toxicological parameters, such as TBARS, serum aspartate aminotransferase (AST), and serum alkaline phosphatase (ALP), showed slight but significant increases after treatment with OX for 9 weeks. These results indicate that OX elicits adaptive responses against oxidative stress in the liver and suggest that the imbalance in redox status might be one of the factors triggering the initial step of OX-induced non-genotoxic carcinogenesis in the liver of rats.

Oxfendazole Resistance in Gastrointestinal Nematodes of Beetal Goats at Livestock Farms of Punjab (Pakistan)

This study was carried out to screen goat farms for anthelmintic resistance (AR) against oxfendazole (OXF) and to determine contributory factors for its development. For this purpose, Beetal goat farms (n = 18) were randomly selected, with natural mixed gastrointestinal nematodosis infection. In vivo (faecal egg count reduction test) and in vitro (egg hatch assay) tests were used to ascertain the presence of AR while a scorecard was used to determine the role of possible contributory factors for oxfendazole resistance. For in vivo test, the experimental animals were divided into two groups of 10 animals each; one group received OXF treatment, while the other served as control. Pre- and post-treatment coproculture was performed to identify the species and genera of nematodes. Egg hatch assay (EHA) was used to confirm the results of FECRT. Fecal egg count reduction test (FECRT) revealed the development of resistance on six farms and post-treatment larval cultures indicated Haemonchus contortus, Trichostrongylus colubriformis, Cooperia curticei, Teladorsagia circumcincta and Oesophagostomum spp. as dominant species with resistance. Furthermore, EHA confirmed the results of FECRT. Among the presumptive factors for AR, the highest composite score was for rotation of anthelmintics followed by treatment frequency, dose rate and nature of medication. The scorecard for the development of AR, used in this study, may be helpful for the assessment of contributory factors of AR.

Effects of formulation concentration on intravenous pharmacokinetics, chirality and in vitro solubility of oxfendazole and its metabolites in sheep

This study compared pharmacokinetic (PK) profiles in sheep dosed intravenously with three different concentrations of oxfendazole (OFZ). An in vitro plasma OFZ solubility study provided additional information on plasma saturation. For the PK study, 18 adult, parasite-free, female Suffolk cross sheep, allocated into three groups (n = 6), were treated intravenously, at a dose rate of 5 mg/kg bodyweight, with aqueous formulations containing at 4, 8 or 16% OFZ. Plasma drug concentrations were measured, for up to 72 h post-treatment, by a validated high performance liquid chromatography method with UV detection. OFZ and fenbendazole sulphone (FBZSO2) were the main metabolites detected in all three experimental groups. In animals given the 4% formulation, OFZ depleted according to a biexponential concentration vs. time curve. In contrast, those given 8 or 16% preparations produced atypical curves fitted by monoexponential equations. No statistically significant differences in area under concentration-time curves (AUC) were observed, but concentration-dependent differences in distribution and mean residence time (MRT) were evident. Compared with 4% OFZ, animals treated with 8 and 16% formulations had slower half-lives of metabolite formation, and lower AUC's, suggesting that OFZ sulphonation may have been modified. In vitro there was evidence of plasma saturation associated with 8 and 16% OFZ preparations. It is concluded that differences in PK profiles were related to OFZ solubility and/or tissue drug precipitation.

TRANSPORT OF ANTHELMINTIC BENZIMIDAZOLE DRUGS BY BREAST CANCER RESISTANCE PROTEIN (BCRP/ABCG2)

Methylcarbamate benzimidazoles [albendazole (ABZ), fenbendazole (FBZ), and their respective sulfoxide derivatives, albendazole sulfoxide (ABZSO) and oxfendazole (OXF)] are therapeutically important anthelmintic agents with low bioavailability. We studied their in vitro interaction with the apical ATP-binding cassette (ABC) drug efflux transporters, breast cancer resistance protein (BCRP/ABCG2), P-glycoprotein (ABCB1), and MRP2 (ABCC2) using MDCKII cells transduced with human MDR1, MRP2, and BCRP, and murine Bcrp1 cDNAs. These ABC drug efflux transporters extrude a wide range of xenotoxins from cells in intestine, liver, and other organs, thus affecting the bioavailability of many compounds. In transport experiments, ABZSO and OXF were transported efficiently by murine Bcrp1 and moderately by human BCRP, but not by MDR1 or MRP2. ABZ and FBZ were not found to be Bcrp1, MRP2, or P-glycoprotein substrates in vitro. OXF was found to be a good BCRP/Bcrp1 inhibitor, with somewhat higher potency in the MDCKII-BCRP cell line. The latter results were confirmed by flow cytometry experiments demonstrating inhibition by OXF of murine Bcrp1- and human BCRP-mediated mitoxantrone transport. Further studies of interactions between OXF and known BCRP/Bcrp1 substrates will be of interest. The use of efficacious BCRP/Bcrp1 inhibitors might increase the extent and duration of systemic exposure to ABZSO and OXF, with possible therapeutically beneficial effects in extra-intestinal infections.

Comparison of milk residue profiles after oral and subcutaneous administration of benzimidazole anthelmintics to dairy cows

The current experimental work reports on the comparison of the milk residue profile of the benzimidazole (BZD) anthelmintics after their administration by the oral and subcutaneous (SC) routes to dairy cows. The cows were distributed in four groups and treated as follows—Group 1: oxfendazole (OFZ) by oral route (5 mg kg −1); Group 2: albendazole (ABZ) by oral route (5 mg kg −1); Group 3: albendazole sulphoxide (ABZSO) by SC administration (3 mg kg −1); Group 4: OFZ by SC route (3 mg kg −1). After drug administrations milk samples were collected and frozen at −20 °C until analyzed by liquid chromatography (LC). A complete validation of the analytical methodology was accomplished. Regression curves were linear over the concentrations examined and the correlation coefficients ( r) ranged between 0.994 and 0.999. The mean extraction recovery range between 77 and 97%. Residual concentrations of OFZ, fenbendazole sulphone (FBZSO 2) and FBZ were recovered in milk after OFZ oral administration. OFZ reached the highest concentration in milk (0.39 ± 0.10 μg ml −1) at 12 h post-treatment, being detected up to 72 h post-treatment. In contrast, FBZ was not detected in cow milk and FBZSO 2 was the main analyte recovered from the milk with the maximum milk residues (0.042 ± 0.003 μg ml −1) achieved at after 36 h following the SC injection of OFZ. ABZSO and ABZSO 2 were the metabolites recovered in milk following oral (ABZ) and SC (ABZSO) treatments in dairy cows. ABZSO 2 was the analyte recovered at the highest residual concentration (0.86 ± 0.33 μg ml −1) at 12 h after oral administration of ABZ. However, ABZSO was the main compound measured in cow milk following its SC injection (0.18 μg ml −1) at 12 h post-treatment. Overall, the total milk residue levels (sum of parent drug and metabolites) were higher after oral compared to parenteral treatments in dairy cows. These results reported here are discussed according to the acceptable maximum residue limits (MRLs) established for BZD compounds in cow milk.

Possible mechanisms underlying the testicular toxicity of oxfendazole in rats.

To clarify the mechanisms underlying the testicular toxicity of oxfendazole (OX), adult Wistar rats were orally administered a dose of 100 mg/kg/day for 3, 7, or 14 days. Assays of sex-related hormones showed a significant decrease in only the estradiol serum level at days 3 and 7, as compared with the control group. Histopathologically, marked degeneration of meiotic spermatocytes was observed in stage XIV-I seminiferous tubules from day 3 onwards, and these spermatocytes gave positive results on terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL). Abnormalities of spermiogenesis such as megakaryospermatids and binucleated spermatids were also observed in the testes of OX-treated rats. Under the electron microscope, lipid accumulation and dilatation of the endoplasmic reticulum were frequently found in the cytoplasm of the Sertoli cells on day 3. These results strongly suggest that OX induces both apoptosis of meiotic spermatocytes, most probably due to disruption of the microtubules, and degeneration of the Sertoli cells, characterized by distended endoplasmic reticulum and prominent cytosolic lipid accumulation.

Quantitative chromatographic determination of several benzimidazole anthelmintic molecules in parasite material

A specific, precise and accurate high-performance liquid chromatographic (HPLC) analytical method has been developed for the quantitative determination of different benzimidazole (BZD) anthelmintics in parasite material ( Moniezia benedeni). Mebendazole (MBZ), oxibendazole (OBZ), flubendazole (FLBZ), albendazole (ABZ) ricobendazole (RBZ), albendazole sulphone (ABZSO 2), fenbendazole (FBZ), oxfendazole (OFZ) and fenbendazole sulphone (FBZSO 2) were measured simultaneously in M. benedeni, a sheep and cattle cestode parasite used as a model of the biological matrix. The recovery, linearity, precision, accuracy, limits of detection and quantification of the method were determined. Drug extraction from the parasite’s tissue homogenate was performed using methanol (liquid phase extraction), and after solvent evaporation, the residual material was cleaned up by solid phase extraction prior to analysis by reversed-phase HPLC. The resolution of all the BZD molecules assayed was obtained on a C 18 reversed-phase (5 μm, 250 mm×4.6 mm) column using acetonitrile and ammonium acetate as the mobile phase and ultraviolet (UV) detection at 292 nm. Regression analyses for all the BZD compounds assayed were linear at concentrations ranging from 1.61 to 64.21 nmol/100 mg protein (triplicate determinations) showing correlation coefficients greater than 0.9922. The developed method is efficient for the simultaneous determination of several benzimidazole anthelmintic molecules in parasite material and useful for the ex vivo and in vivo characterisation of the kinetics of drug uptake/diffusion in target parasites, which seems to be relevant to optimise parasite control both in human and veterinary medicine.

Dexamethasone decreases plasma levels of the prochiral fenbendazole and its chiral and achiral metabolites in sheep

1. The effect of co-administration of either short- or long-acting formulations of DXM on hepatic function and the plasma pharmacokinetic behaviour of prochiral fenbendazole (FBZ) and its metabolites was evaluated in sheep. 2. Neither DXM treatment markedly affected any of the biochemical markers of hepatic function tested. In contrast, both formulations significantly modified the plasma pharmacokinetic behaviour of FBZ and its metabolites. 3. Plasma FBZ concentrations and the associated area under the time-concentration curves were significantly lower, although the plasma detection period was longer (72 versus 48 h) in the DXM pretreated animals compared with those given FBZ alone. 4. DXM also appeared to alter the pattern of FBZ absorption, possibly through effects on abomasal pH. The shape of the plasma concentration-time curves for oxfendazole (OFZ) and fenbendazole sulphone (FBZSO 2) were similar to FBZ, raising the possibility that DXM treatment may have altered the liver biotransformation of the parent drug. 5. The concentrations of the (+) chiral metabolite of OFZ were significantly lower in DXM pretreated animals compared with those given FBZ alone. The trend was similar for the (−) antipode, although the differences between DXM pretreated and non-pretreated animals were not statistically significant.