Albendazole Sulphoxide Research Articles

Determination of albendazole metabolites by direct injection of bovine plasma and multidimensional achiral–chiral high performance liquid chromatography

The development and validation of a fully automated achiral–chiral high performance liquid chromatography (HPLC) method for the simultaneous determination of albendazole metabolites: enantiomers of albendazole sulphoxide (ABZ-SO), albendazole sulphone (ABZ-SO 2) and albendazole 2-aminosulphone (ABZ-SO 2NH 2) in bovine plasma are described. This method involves an octyl restricted access media bovine serum albumin column (C 8-RAM-BSA) (50 mm × 4.6 mm I.D.) for sample clean-up, followed by enantioselective analysis on a column containing an amylose tris(3,5-dimethylphenylcarbamate) stationary phase (150 mm × 4.6 mm I.D.). The chromatographic separations of all target compounds were performed at 30 °C using a mobile phase composed of phosphate buffer (10 mmol L −1; pH 7.5):acetonitrile (60:40, v/v), flow rate of 0.5 mL min −1 and fluorescence detection at 290 nm and 320 nm, excitation and emission, respectively. The influence of different organic modifiers and chiral selector of the stationary phase on enantioseparation of ABZ-SO was investigated. The method developed was fully validated. The calibration curves were linear in the concentration range of 40.00–1280 ng mL −1 for each albendazole sulphoxide enantiomer, 10.0–320 ng mL −1 for albendazole sulphone and 20.0–320 ng mL −1 for albendazole 2-aminosulphone. The inter- and intra-day precision ranged from 0.760% to 7.79% relative standard deviation (R.S.D.), and the accuracy ranged 101% from 114% of the nominal values while the transfer efficiency was in the range of 84.4–103%. The method showed good linearity, precision, accuracy, sensitivity and selectivity allowing it to be appropriate for further pharmacokinetics and metabolism studies of albendazole.

Kinetic disposition of albendazole in goats subclinically infected with gastrointestinal nematodes vis-à-vis naive animals following oral and intraruminal administration

The influence of subclinical nematodosis on the kinetic disposition of albendazole was evaluated in goats following oral and intraruminal administration. The disposition curves of its metabolites indicated increased uptake of the drug in parasitized goats following intraruminal compared to oral dosing (P < 0.05). The midpoint for the pharmacologically active metabolite, albendazole sulphoxide, in the circulatory compartment was around 0.6 mug ml- 1 both in parasitized and naïve goats. The period of exposure to this concentration was around 14 h (oral route), 18 h (intraruminal route) and 16 h (oral route), 17 h (intraruminal route) in parasitized and naïve goats, respectively. As the duration of exposure of parasites to the toxic concentration of the anthelmintically active metabolite was prolonged, it could be assumed that intraruminal delivery of the drug would improve the efficacy of albendazole in parasitized goats.

&lt;i&gt;In vitro&lt;/i&gt; Evaluation of Benzimidazole Carbamates on Cystic Larvae of Three Cestode Parasite Models

Benzimidazole carbamates are broad-spectrum anthelmintics which have limited solubility and hence poor absorption following oral administration. Consequently, their use is limited almost entirely to the treatment of intestinal helminthiasis. This study was designed to compare two different preparations (polyvinylpyrrolidone-drug solutions and dimethylsulfoxide-drug suspensions) of mebendazole, albendazole and ricobendazole (albendazole sulphoxide) by analyzing their i n vitro efficacy on Echinococcus granulosus, Mesocestoides corti and Taenia crassiceps parasite models at concentrations of 5, 25, 50 and 100 μg/ml. The effects of the two drug preparations were evaluated on days 2, 4, 7 and 11 post inoculation. The in vitro effects of the two preparations on the assayed cystic larvae showed that polyvinylpyrrolidone-drug solutions were more efficacious than dimethylsulfoxide-drug suspensions in the order of mebendazole >albendazole >ricobendazole. Moreover, the three parasite models complement one another. Keywords : In vitro efficacy, Echinococcus granulosus, Mesocestoides corti, Taenia crassiceps, benzimidazole carbamates, cysts viability The East and Central African Journal of Pharmaceutical Sciences Vol. 9 (2) 2006: pp. 31-39

Anthelmintic resistance in cattle nematodes in northwestern São Paulo State, Brazil

The present study was carried out in the northwestern region of São Paulo State, Brazil, to determine the anthelmintic resistance status in cattle naturally infected with gastrointestinal nematodes. The anthelmintics tested were levamisole phosphate (Ripercol ®, Fort Dodge), albendazole sulphoxide (Ricobendazole, Fort Dodge), ivermectin (Ivomec ®, Merial) and moxidectin (Cydectin ®, Fort Dodge), administered at the doses recommended by the manufacturers. From April 2002 to May 2004, 25 cattle farms were evaluated. On each farm, steers were divided into treatment and control (not treated) groups based on fecal egg counts (FEC). Between 7 and 10 days after the anthelmintics administration, fecal samples were collected from each animal for post-treatment FEC. Fecal cultures from each group were also prepared for larval identification. After treatment, mean FEC reduction (FECR) in treatment groups (compared with control groups) was assessed on each farm. FECR was lower than 90% on 23 farms after ivermectin treatment. On 19 farms, FECR of 100% was recorded following moxidectin treatment; on the remaining 6, FECR ranged from 90% to 97.2%. After albendazole treatment, FECR was higher than 90% on 20 farms and ranged from 47.4% to 84.6% on other 5. After levamisole treatment, FECR was higher than 90% on 23 farms and equal to 47.4% and 73.7% on other 2 farms. Results indicated the presence of resistant Cooperia spp. and Haemonchus spp., especially to ivermectin; on some farms, resistance to albendazole and levamisole was also observed.

Efficacy of nitazoxanide, tizoxanide and tizoxanide/albendazole sulphoxide combination against Taenia crassiceps cysts

Neurocysticercosis is a common parasitic disease in the CNS in humans caused by the metacestode Taenia solium, with high incidence in developing countries. Albendazole is the drug of choice. However, a wide interindividual variability in the response has been reported. In order to evaluate alternative treatment options, the in vitro efficacy of nitazoxanide, its main metabolite tizoxanide as well as the tizoxanide and albendazole sulphoxide combination was tested against Taenia crassiceps cysts. T. crassiceps cysts were incubated in culture medium containing different concentrations of nitazoxanide, tizoxanide and albendazole sulphoxide (0.037-0.42 microg/mL). The effect of the tizoxanide and albendazole sulphoxide combination was evaluated in a fixed-concentration ratio (1:1). Isobolographic analyses were used to define the kind of interaction between drugs. Morphological and ultrastructural alterations over the parasite tissue were observed by light and transmission electron microscopy. Nitazoxanide and tizoxanide exhibited cestocidal activity which was time-concentration-dependent. The EC(50) values were 0.15, 0.12 and 0.080 microg/mL for nitazoxanide, tizoxanide and albendazole sulphoxide, respectively. No statistical differences between EC(50) values were found, indicating that nitazoxanide and tizoxanide are equally potent as albendazole sulphoxide. The effect of the tizoxanide and albendazole sulphoxide combination was faster than that observed with each drug alone. Isobolographic analysis showed that the effect of the combination was additive. Nitazoxanide and tizoxanide had an effect on the germinal layer, where lipid droplets were found. Nitazoxanide and tizoxanide produced less damage than albendazole sulphoxide on the germinal layer. After the tizoxanide and albendazole sulphoxide combination, a high accumulation of lipid droplets within the germinal layer of the parasite was found. Our results suggest that nitazoxanide in combination with albendazole could be useful for treatment of cysticercosis infections. Additional in vivo studies are required to confirm this hypothesis.

Non-disjunction events induced by albendazole in human cells

Albendazole (ABZ), a benzimidazole carbamate used for the treatment of several human helminthiases has high affinity for tubulin, which results in an inhibition of microtubule polymerization, blocking several vital processes in the parasites, such as motility and nutrient uptake. The ability of ABZ to act as mitotic spindle poison leads to a potential risk for aneuploidy induction in exposed human beings. ABZ, as well as albendazole sulphoxide (ABZSO), its main metabolite, induce micronuclei in human cells in a dose-dependent manner. Despite recognition that ABZ and ABZSO increase micronucleus frequency, their potential as inducers of non-disjunction in human cells, an event considered more frequent than chromosome loss, and one of the main mechanisms involved in aneuploidy induction, has not been evaluated. In the present work, we investigated the ability of ABZ and ABZSO to induce non-disjunction in cultured human lymphocytes. Non-disjunction was scored by chromosome-specific FISH using a classical or alpha satellite probe for chromosomes 1 and 7, respectively. Significant increase in non-disjunction events that involved either chromosome were observed in cells treated with ABZ or ABZSO. Both ABZ and ABZSO induced non-disjunction at lower concentrations than those at which MN were observed.

Plasma Disposition and Faecal Excretion of Netobimin Metabolites and Enantiospecific Disposition of Albendazole Sulphoxide Produced in Ewes

Netobimin (NTB) was administered orally to ewes at 20 mg/kg bodyweight. Blood and faecal samples were collected from 1 to 120 h post-treatment and analysed by high-performance liquid chromatography (HPLC). Using a chiral phase-based HPLC, plasma disposition of albendazole sulphoxide (ABZSO) enantiomers produced was also determined. Neither NTB nor albendazole (ABZ) was present and only ABZSO and albendazole sulphone (ABZSO(2)) metabolites were detected in the plasma samples. Maximum plasma concentrations (C(max)) of ABZSO (4.1 +/- 0.7 microg/ml) and ABZSO(2) (1.1 +/- 0.4 microg/ml) were detected at (t(max)) 14.7 and 23.8 h, respectively following oral administration of netobimin. The area under the curve (AUC) of ABZSO (103.8 +/- 22.8 (microg h)/ml) was significantly higher than that ABZSO(2)(26.3 +/- 10.1 (microg h)/ml) (p < 0.01). (-)-ABZSO and (+)-ABZSO enantiomers were never in racemate proportions in plasma. The AUC of (+)-ABZSO (87.8 +/- 20.3 (microg h)/ml) was almost 6 times larger than that of (-)-ABZSO (15.5 +/- 5.1 (microg h)/ml) (p < 0.001). Netobimin was not detected, and ABZ was predominant and its AUC was significantly higher than that of ABZSO and ABZSO(2), following NTB administration in faecal samples (p > 0.01). Unlike in the plasma samples, the proportions of the enantiomers of ABZSO were close to racemic and the ratio of the faecal AUC of (-)-ABZSO (172.22 +/- 57.6 (microg h)/g) and (+)-ABZSO (187.19 +/- 63.4 (microg h)/g) was 0.92. It is concluded that NTB is completely converted to ABZ by the gastrointestinal flora and absorbed ABZ is completely metabolized to its sulphoxide and sulphone metabolites by first-pass effects. The specific behaviour of the two enantiomers probably reflects different enantioselectivity of the enzymatic systems of the liver that are responsible for sulphoxidation and sulphonation of ABZ.

A dual anthelmintic treatment strategic scheme for the control of fasciolosis in dairy sheep farms

A clinical longitudinal field trial was conducted on a dairy sheep farm in southern Italy to assess the effectiveness of a novel anthelmintic treatment strategic scheme against Fasciola hepatica. The scheme utilizes a dual anthelmintic treatment (DAT), i.e., the use of either one of two different anthelmintics on the flock, albendazole sulphoxide (SO) at 1-month intervals and rafoxanide at 2-month intervals, administered to the lactating and non-lactating animals, respectively. The DAT strategic scheme lasted 3 years. In Year 1 and Year 2, shotgun monthly DATs for 5 consecutive months (July, August, September, October, and November) were performed on the flock. In Year 3 there was only one monthly DAT, in July. Overall, the DAT scheme reduced the prevalence of F. hepatica infection by 94.4% (from an average prevalence of 71.1% during the pre-DAT period to an average prevalence of 4.0% during Year 3), and the eggs/gram of faeces (EPG) from 29.3 to 1.3. In conclusion, the DAT strategic scheme reported in the present study successfully reduced both the prevalence and EPGs of F. hepatica to a level at which there were no longer any clinical symptoms of the disease. This scheme did not influence the albendazole SO efficacy against GI nematodes and might be used for the treatment of fasciolosis in dairy sheep farms.

Evaluation of the efficacy of albendazole sulphoxide and praziquantel in combination on Taenia crassiceps cysts: in vitro studies

Praziquantel and albendazole are currently used for chemotherapeutic treatment of neurocysticercosis. Albendazole has been found to be more effective than praziquantel; however, it is well known that not all patients will show a complete resolution of cysts. Searching for more effective treatments, this study was designed to evaluate the effect of the combination of praziquantel and albendazole sulphoxide in a Taenia crassiceps in vitro model as well as the kind of interaction between both drugs. In order to determine the concentration that produced 50% effect (EC50), T. crassiceps cysts were incubated in culture medium containing praziquantel (0.005-0.04 microg/mL), albendazole sulphoxide (0.021-0.16 microg/mL) or the combination of praziquantel and albendazole sulphoxide in a fixed-dose ratio (1:1). The experimental concentration (EC50Exp) of the combination was determined from the concentration-response curve constructed from the combined drug treatment. Isobolographic analyses were used to define the nature of the interaction between praziquantel and albendazole sulphoxide. Morphological and ultrastuctural alterations after different treatments over the parasite tissue were observed by light and transmission electron microscopy. The changes in ultrastructure were more marked with the praziquantel and albendazole sulphoxide combination. Also the cysticidal effect of the combination was observed earlier than that of each drug alone. When isobolographic analysis was employed, we found that the experimental EC50 value (0.042 microg/mL) was not significantly different from the theoretical EC50 value (0.035 microg/mL), which indicates an additive interaction between praziquantel and albendazole sulphoxide. Our study suggests that the combination of praziquantel and albendazole sulphoxide could potentially improve the current neurocysticercosis treatment.

Assessments of pharmacokinetic drug interactions and tolerability of albendazole, praziquantel and ivermectin combinations

The pharmacokinetic interactions and tolerability of albendazole, praziquantel and ivermectin combinations were assessed in 23 healthy Thai volunteers (12 males and 11 females). The study was an open, randomised, three-way crossover design in which each subject attended the study on three separate occasions (Phases I, II and III), of 4 d or 8 d each, with at least 1 or 2 weeks (but not longer than 2 months) between each phase. All subjects received the three study drug regimens as follows: regimen I, oral praziquantel (40 mg/kg body weight); regimen II, oral ivermectin (200 microg/kg body weight) given concurrently with an oral dose of albendazole (400 mg); and regimen III, oral ivermectin given concurrently with albendazole and praziquantel. All treatment regimens showed acceptable tolerability profiles. The incidence of overall drug-related adverse events was significantly higher following regimens I (12/23) and III (7/23) compared with that following regimen II (0/23). Six statistically significant changes in the pharmacokinetic parameters of albendazole sulphoxide (Cmax, AUC0-infinity, Vz/F, CL/F), praziquantel (Vz/F) and ivermectin (AUC0-infinity) were observed when the three drugs were given concurrently. However, based on US Food and Drug Administration criteria, these changes were not considered of clinical relevance.

Liver microsomal biotransformation of albendazole in deer, cattle, sheep and pig and some related wild breeds

Albendazole (ABZ) biotransformation was studied in vitro in liver microsomes of adult noncastrated male farm animals (ram, buck, bull and boar), castrated adult males (wether, billy and hog), and free living males (fallow buck, red deer stag, mouflon ram, roe buck and wild boar). Liver microsomal fractions were incubated with either ABZ or racemic albendazole sulphoxide (ABZSO). ABZ was extensively metabolized to the (+) and (-) enantiomers of ABZSO, whereas ABZSO underwent a slow oxidation to albendazole sulphone (ABZSO2) in all species. In all species both ABZSO enantiomers were detected. The chiral ratio, (+)-ABZSO/(-)-ABZSO, was greater than one in farm animals, mouflon and wild boar, and less than one in three species of deer. For total ABZ sulphoxidation, deer like species had lower values compared to the other species. Mouflon ram and ram had lower total sulphoxidation rates compared to wethers, as well as ABZ suphoxidation towards (+)-ABZSO. No significant difference occurred comparing ABZSO formation in mouflon ram and ram, but ABZSO2 formation rate in mouflon ram was higher than in rams and wethers. Roe deer stag, fallow buck and red deer stag did not differ in both total-ABZSO and (-)-ABZSO synthesis rates and roe deer stag and fallow buck did not differ in synthesis rates of (+)-ABZSO and ABZSO2. The bull differed from other species in all metabolites studied, except for red deer stag and boar in (-)-ABZSO synthesis rate. The extent of ABZSO sulphonation to ABZSO2 in bull microsomes was more than twice that of other species.

Plasma disposition and faecal excretion of oxfendazole, fenbendazole and albendazole following oral administration to donkeys

Fenbendazole (FBZ), oxfendazole (fenbendazole sulphoxide, FBZSO), and albendazole (ABZ) were administered orally to donkeys at 10 mg/kg bodyweight. Blood and faecal samples were collected from 1 to 120 h post-treatment. The plasma and faecal samples were analysed by high performance liquid chromatography (HPLC). The parent molecule and its sulphoxide and sulphone (FBZSO 2) metabolites did not reach detectable concentrations in any plasma samples following FBZ administration. ABZ was also not detected in any plasma samples, but its sulphoxide and sulphone metabolites were detected, demonstrating that ABZ was completely metabolised by first-pass mechanisms in donkeys. Maximum plasma concentrations ( C max) of FBZSO (0.49 μg/mL) and FBZSO 2 (0.60 μg/mL) were detected at ( t max) 5.67 and 8.00 h, respectively, following administration of FBZSO. The area under the curve (AUC) of the sulphone metabolite (10.33 μg h/mL) was significantly higher than that of the parent drug FBZSO (5.17 μg h/mL). C max of albendazole sulphoxide (ABZSO) (0.08 g/mL) and albendazole sulphone (ABZSO 2) (0.04 μg/mL) were obtained at 5.71 and 8.00 h, respectively, following ABZ administration. The AUC of the sulphoxide metabolite (0.84 μg h/mL) of ABZ was significantly higher than that of the sulphone metabolite (0.50 μg h/mL). The highest dry-faecal concentrations of parent molecules were detected at 32, 34 and 30 h for FBZSO, FBZ and ABZ, respectively. The sulphide metabolite was significantly higher than the parent molecule after FBZSO administration. The parent molecule was predominant in the faecal samples following FBZ administration. After ABZ administration, the parent molecule was significantly metabolised, probably by gastrointestinal microflora, to its sulphoxide metabolite (ABZSO) that showed a similar excretion profile to the parent molecule in the faecal samples. The AUC of the parent FBZ was significantly higher than that of FBZSO and ABZ in faeces. It is concluded that the plasma concentration of FBZSO was significantly higher than that of FBZ and ABZ. Although ABZ is not licensed for use in Equidae, its metabolites presented a greater plasma kinetic profile than FBZ which is licensed for use in horses. A higher metabolic capacity, first-pass effects and lower absorption of benzimidazoles in donkeys decrease bioavailability and efficacy compared to ruminants.

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.

Liver hydatid disease: Morphological changes of protoscoleces after albendazole therapy

Postoperative recurrence of the liver hydatid disease befalls approximately 10-30% of patients. Preoperative or postoperative therapy with albendazole in single therapeutic protocol (800 mg/d, within 28 days) indicated the need to evaluate the hydatid cyst liquid protoscoleces viability. Morphological changes of protoscoleces following the treatment with drugs are not well known. To estimate the viability of protoscoleces after preoperative or postoperative albendazole therapy, and their ability for cystic metamorphosis. A prospective, randomized clinical trial included 30 patients with liver hydatid disease, treated with albendazole and surgically (I group), and 30 patients in the control group treated only surgically (II group). The concentration of albendazole and its active metabolite albendazole sulphoxide in the cysts contents were determined using HPLC. Estimation of protoscoleces viability was based on the established micromorphologic criteria, and compared between the patients treated with albendazole, and the patients treated only surgically. Biological assessment of the viability was performed on protoscoleces with uncertain signs of the disturbed viability (unchanged structure, evaginated, without movements) using intraperitoneal injection of 1 ml of protoscoleces prepared suspension to AO type of rats. The concentration of albendazole in cysts' contents ranged from 0 to 64.9 microg/ml, and of its active metabolite from 0.5 to 40.8 microg/ml. The presence of fully viabile protoscoleces in the albendazol treated patients was significantly lower than in the control group. A significant difference was noticed in the presence of disintegrated protoscoleces without movements in the albendazol treated group, compared to the control group. Biological assessment of the viability showed incapability of these protoscoleces for cystic metamorphoses. Low viability of parasites due to medicamentous therapy is very useful and important to surgeons, because the fertility of cysts is lower, and the risk of the disease recurrence is reduced.

Multi-residue method for the determination of benzimidazoles in bovine liver

A method has been developed to analyse for 12 benzimidazole drug residues in bovine liver. Liver samples were extracted with ethyl acetate, sample extracts were defatted with hexane and cleaned-up by automated SPE on C 18 solid phase extraction cartridges. Aliquots of the extracts were analysed by LC with UV detection (298 nm). The method was validated in bovine liver, according to the criteria defined in Commission Decision 2002/657/EC. The decision limit (CC α) was between MRL + 12% and MRL + 25% and the detection capability (CC β) was between MRL + 25% and MRL + 45% for the range of benzimidazoles investigated. The results of the inter-assay study, which was performed by fortifying bovine liver samples ( n = 6) in three separate assays, show the mean recovery to be between 60% and 100% for albendazole sulphoxide, albendazole sulphone, thiabendazole, oxfendazole/fenbendazole sulphoxide, hydroxy-mebendazole, fenbendazole sulphone, oxibendazole, mebendazole and flubendazole. Lower mean recovery was obtained for amino-flubendazole and albendazole (approximately 50%) and amino-albendazole sulphone (approximately 25%). The precision of the method, expressed as R.S.D. values for the within-laboratory repeatability, was generally below 25%.

Implications of fungicidal effects of benzimidazole compounds on Duddingtonia flagrans in integrated nematode parasite management in livestock.

An in vitro trial with carbendazim fungicide on the growth profile of the predatory fungus Duddingtonia flagrans was undertaken and in vivo trials in sheep and buffaloes, fed on chlamydospores of D. flagrans and administered albendazole anthelmintic, were conducted. Although no growth inhibition was detected at a carbendazim concentration of 0.05 ppm, growth inhibition was recorded of 50% and above at concentrations of 0.25 and 1.00 ppm (p < 0.001) and of around 90% at concentrations of 2.00 to 5.00 ppm (p <0.0001). Scanty recovery of the fungus was made from faecal culture 48 h following a single dose of albendazole both in sheep and buffaloes. However, profuse fungal recovery was made from 96 h post dosing onwards. When the drug was used as an intraruminal slow-release capsule, no faecal fungal recovery could be made from day 3 after administration of the capsule, when the albendazole sulphoxide concentration was around 1.0 microg/ml. However, profuse and scanty fungal recovery could be made on days 1 and 2, respectively, after administration of the capsule, when the plasma albendazole sulphoxide concentration was around 0.4 and 0.9 microg/ml, respectively. The implications for use of a combination of anthelmintics and biological control in sustainable parasite control programmes are discussed.

Quantitative determination of albendazole metabolites in sheep spermatozoa and seminal plasma by liquid chromatographic analysis with fluorescence detection

A new analytical method for the simultaneous quantitative determination of albendazole metabolites in sheep spermatozoa and seminal plasma at levels down to 46.5 ng/mL for albendazole sulphoxide (ABZ-SO), 7.5 ng/mL for albendazole sulphone (ABZ-SO 2) and 12 ng/mL for albendazole 2-aminosulphone (ABZ-SO 2NH 2) has been developed. Analytes were extracted from alkalinized samples with ethyl acetate. Separation was carried out on a C 18 column in the presence of tetra -n-butylammonium (TBA) hydrogen sulphate and octanesulphonate sodium (OCT), as ion-pair agents. Fluorometric detection was performed with excitation and emission wavelengths set at 290 and 320 nm, respectively. Accuracy data showed overall recoveries (±S.E.M.) of 83.1±1.2% for ABZ-SO, 98.8±0.6% for ABZ-SO 2 and 85.3±0.7% for ABZ-SO 2NH 2, in spermatozoa. Respective values in seminal plasma were 88.0±0.9%, 97.7±0.5% and 93.2±1.7%. Precision data suggested coefficient of variation (CV%) values lower than 5.9% for spermatozoa and 3.8% for seminal plasma. The method was successfully applied for the determination of the three albendazole metabolites in semen samples collected from rams that had been orally administered albendazole.

Reversed-phase liquid chromatographic method with fluorescence detection for the simultaneous determination of albendazole sulphoxide, albendazole sulphone and albendazole 2-aminosulphone in sheep plasma

A rapid and sensitive HPLC method for the simultaneous quantification of albendazole sulphoxide (ABZ-SO), albendazole sulphone (ABZ-SO 2) and albendazole 2-aminosulphone (ABZ-SO 2NH 2) in sheep blood plasma has been developed. Plasma samples were extracted with ethyl acetate under alkaline conditions. Separation was achieved on a C 18 reversed-phase analytical column, in the presence of positively- (tetra- n-butylammonium hydrogen sulphate) and negatively-charged (octanesulphonate sodium) pairing ions, while detection was performed fluorometrically. Excitation and emission wavelengths were 290 and 320 nm, respectively. Limits of quantification were defined at 39 ng/ml for ABZ-SO, 4.95 ng/ml for ABZ-SO 2 and 4 ng/ml for ABZ-SO 2NH 2. Accuracy data, in terms of recovery efficiency showed overall values (±S.E.M.) of 85.6±1.0% for ABZ-SO, 100.0±1.0% for ABZ-SO 2 and 89.1±0.6% for ABZ-SO 2NH 2. The method was successfully applied to quantitatively determine the three albendazole metabolites in plasma samples collected from sheep that had been orally administered albendazole.

Comparative efficacy of six anthelmintics for the control of gastrointestinal nematodes in sheep in Matanzas, Cuba

The efficacy of injectable levamisol, a mixture of levamisol and niclosamide, oral ivermectin, injectable ivermectin, oral albendazole and albendazole sulphoxide was evaluated in two farms with the dose recommended by the manufacturer. In the LABIOFAM farm 72 commercial sheep (uncontrolled crossbred Suffolk and Pelibuey) and in the Dos Mercedes farm 77 pure Pelibuey sheep were used. The selection of the animals was made according to their weight and an initial faecal egg count (FEC) superior to 100 eggs per gram (EPG). Animals were randomly divided into seven groups: LV (injectable levamisol), NC (tetramisol and niclosamida), LB (injectable ivermectin), IO (oral ivermectin), AZ (albendazol), LZ (albendazole sulphoxide) and C untreated control group. The FEC was carried out 14 and 4 days before, and the day of, drenching to assess the level of parasitic infection. A faecal egg count reduction test (FECRT) was performed at the 11th day to all groups. Three days after drenching two animals per group were slaughtered to determine the worm burden in each group. The results obtained showed evidences of Haemonchus spp. in LABIOFAM and Trichostrongylus spp. in Dos Mercedes for LV and NC, respectively. These results were reinforced with the predominance of each genus when helminthological necropsies were carried out. The efficacy of the other products (LB, LZ, AZ and IO) did not differ among them at the 11th day after drenching. These results indicate that the imidazotiazole group has showed a low level of anthelmintic resistance reached a questionable efficacy, but the rest of the products seem to be effective against gastrointestinal parasitism in sheep.

Albendazole sulphoxide concentrations in plasma of endemic normals from a lymphatic filariasis endemic region using liquid chromatography

A simple and sensitive reversed-phase isocratic HPLC method for the determination of albendazole and its metabolites has been developed. The mobile phase consisting of acetonitrile–water–perchloric acid (70%) (30:110:0.06 (v/v/v)) was pumped at a flow rate of 0.80 ml/min on a 5 μm, reverse phase, Discovery ® RPamide C16 column with UV detection at 290 nm. The calibration graphs were linear in the range of 0.05–1 μg/ml for albendazole, albendazole sulphoxide and albendazole sulphone. The limit of quantification was 50 ng/ml for albendazole, 25 ng/ml for albendazole sulphoxide and 30 ng/ml for albendazole sulphone. The within-day and day-to-day coefficient of variation averaged 4.98 and 6.95% for albendazole, 3.83 and 6.83% for albendazole sulphoxide and 3.44 and 5.51% for albendazole sulphone, respectively. The mean extraction recoveries of albendazole, albendazole sulphoxide and albendazole sulphone were 79.25, 93.03 and 88.78%, respectively. The method was applied to determine the plasma levels of albendazole sulphoxide in endemic normals administered with albendazole during pharmacokinetic studies.