Hapten Synthesis and Monoclonal Antibody Preparation for Simultaneous Detection of Albendazole and Its Metabolites in Animal-Origin Food

Albendazole (ABZ) is one of the benzimidazole anthelmintics, and the overuse of ABZ in breeding industry can lead to drug resistance and a variety of toxic effects in humans. Since the residue markers of ABZ are the sum of ABZ and three metabolites (collectively referred to as ABZs), albendazole-sulfone (ABZSO2), albendazole-sulfoxide (ABZSO), and albendazole-2-amino-sulfone (ABZNH2SO2), an antibody able to simultaneously recognize ABZs with high affinity is in urgent need to develop immunoassay for screening purpose. In this work, an unreported hapten, 5-(propylthio)-1H-benzo[d]imidazol-2-amine, was designed and synthesized, which maximally exposed the characteristic sulfanyl group of ABZ to the animal immune system to induce expected antibody. One monoclonal antibody (Mab) that can simultaneously detect ABZs was obtained with IC50 values of 0.20, 0.26, 0.77, and 10.5 μg/L for ABZ, ABZSO2, ABZSO, and ABZNH2SO2 in ic-ELISA under optimized conditions respectively, which has been never achieved in previous reports. For insight into the recognition profiles of the Mab, we used computational chemistry method to parameterize cross-reactive molecules in aspects of conformation, electrostatic fields, and hydrophobicity, revealing that the hydrophobicity and conformation of characteristic group of molecules might be the key factors that together influence antibody recognition with analytes. Furthermore, the practicability of the developed ic-ELISA was verified by detecting ABZs in spiked milk, beef, and liver samples with recoveries of 60% to 108.8% and coefficient of variation (CV) of 1.0% to 15.9%.

Simultaneous Determination of Albendazole and Its Three Metabolites in Pig and Poultry Muscle by Ultrahigh-Performance Liquid Chromatography-Fluorescence Detection

A fast, simple and efficient ultrahigh-performance liquid chromatography-fluorescence detection (UPLC-FLD) method for the determination of residues of albendazole (ABZ) and its three metabolites, albendazole sulfone (ABZ-SO2), albendazole sulfoxide (ABZ-SO), and albendazole-2-aminosulfone (ABZ-2NH2-SO2), in pig and poultry muscle (chicken, duck and goose) was established. The samples were extracted with ethyl acetate, and the extracts were further subjected to cleanup by utilizing a series of liquid–liquid extraction (LLE) steps. Then, extracts were purified by OASIS® PRiME hydrophilic-lipophilic balance (HLB) solid-phase extraction (SPE) cartridges (60 mg/3 mL). The target compounds were separated on an ACQUITY UPLC® BEH C18 (2.1 mm × 100 mm, 1.7 μm) chromatographic column, using a mobile phase composed of 31% acetonitrile and 69% aqueous solution (containing 0.2% formic acid and 0.05% triethylamine). The limits of detection (LODs) and limits of quantification (LOQs) of the four target compounds in pig and poultry muscle were 0.2–3.8 µg/kg and 1.0–10.9 µg/kg, respectively. The recoveries were all above 80.37% when the muscle samples were spiked with the four target compounds at the LOQ, 0.5 maximum residue limit (MRL), 1.0 MRL, and 2.0 MRL levels. The intraday relative standard deviations (RSDs) were less than 5.11%, and the interday RSDs were less than 6.29%.

DEVELOPMENT OF METHODS FOR QUANTITATIVE DETERMINATION OF ALBENDAZOLE AND ITS METABOLITES IN BIOLOGICAL TISSUES USING HPLC / FLD

This manuscript presents the results of developed method is intended for clinical and pharmaceutical studies of veterinary drugs based on the active substances albendazole ([5-(propylthio)-1H-benzimidazol-2yl]carbamic acid methyl ester) and its main metabolites, albendazole sulfoxide, albendazole sulfone, and albendazole-2- aminosulfone in sheep muscles. Tissue samples were made alkaline with sodium carbonate, extracted twice with acetonitrile and degreased with hexane. The extracts are further purified using a series of liquid-liquid extraction and solid phase extraction. After concentration and drying, the dry residue was recovered in the mobile phase. Separation was performed on an inverted phase Acclaim 120 C18 column using acetonitrile and phosphate buffer as the mobile phase. The gradient mode of eluents was used during 12 min at a flow rate of 1,8 ml/min. The peak retention time of albendazole 2-aminosulfoam is 3,0 min, albendazole sulfoxide is 3,9 min, albendazole sulfone is 4,8 min, and the retention time of albendazole peak is 6,6 min. The specificity of the analytical method was checked by comparing the chromatographic separation of a sample of muscle tissue enriched with a standard solution of a mixture of albendazole and its metabolites at the level of MDR (100 μg/kg) and a sample of muscle tissue placebo. The validation parameters of the method “recovery” and “coefficient of variation” were considered in accordance with the criteria of Council Directive 2002/657/EC. The procedure of sample preparation of fortified tissues to construct calibration graphs is described in the manuscript. The mean recovery from fortified muscle tissue in the range of 50-150 μg/kg albendazole, albendazole sulfoxide, albendazole sulfone and albendazole 2-aminosulfon was 100.2; 100.9; 100.7 and 100.2%, respectively. The average coefficient of variation for each compound was ≤ 10%. The method is linear in the concentration range of 25.0 - 200.0 μg/kg of each analyte. The results obtained in the study of the linearity of this technique were used to estimate the correctness and convergence. The accuracy of the measurements was evaluated by examining the known amounts of analytes added to the control muscle tissue. Recovery data are acceptable because they are within ± 10% of the target value. The method has sufficient convergence (accuracy). The evaluation of the intermediate accuracy of albendazole and its metabolites was assessed on three different days of analysis. The limit of detection for albendasole is 0.4 μg/kg. The average CV for each compound was <10%. The procedure was confirmed and then applied to determination albendazole and its metabolites in the sheep muscle tissue obtained after feeding animals with the veterinary drug albendazole. The HPLC/FLD method can be used for withdrawal time albendazole and its metabolites.

Pharmacokinetics of Albendazole, Albendazole Sulfoxide, and Albendazole Sulfone Determined from Plasma, Blood, Dried-Blood Spots, and Mitra Samples of Hookworm-Infected Adolescents

ABSTRACT Albendazole is an effective anthelmintic intensively used for decades. However, profound pharmacokinetic (PK) characterization is missing in children, the population mostly affected by helminth infections. Blood microsampling would facilitate PK studies in pediatric populations but has not been applied to quantify albendazole’s disposition. Quantification methods were developed and validated using liquid chromatography-tandem mass spectrometry to analyze albendazole and its metabolites albendazole sulfoxide and albendazole sulfone in wet samples (plasma and blood) and blood microsamples (dried-blood spots [DBS]; Mitra). The use of DBS was limited by a matrix effect and poor recovery, but the extraction efficiency was constant throughout the concentration range. Hookworm-infected adolescents were venous and capillary blood sampled posttreatment with 400 mg albendazole and 25 mg/kg oxantel pamoate. Similar half-life (t1/2 = ∼1.5 h), time to reach the maximum concentration (tmax = ∼2 h), and maximum concentration (Cmax = 12.5 to 26.5 ng/ml) of albendazole were observed in the four matrices. The metabolites reached Cmax after ∼4 h with a t1/2 of ca. 7 to 8 h. A statistically significant difference in albendazole sulfone’s t1/2 as determined by using DBS and wet samples was detected. Cmax of albendazole sulfoxide (288 to 380 ng/ml) did not differ among the matrices, but higher Cmax of albendazole sulfone were obtained in the two microsampling devices (22 ng/ml) versus the wet matrices (14 ng/ml). In conclusion, time-concentration profiles and PK results of the four matrices were similar, and the direct comparison of the two microsampling devices indicates that Mitra extraction was more robust during validation and can be recommended for future albendazole PK studies.

In VitroandIn VivoDrug Interaction Study of Two Lead Combinations, Oxantel Pamoate plus Albendazole and Albendazole plus Mebendazole, for the Treatment of Soil-Transmitted Helminthiasis

ABSTRACTThe current treatments againstTrichuris trichiura, albendazole and mebendazole, are only poorly efficacious. Therefore, combination chemotherapy was recommended for treating soil-transmitted helminthiasis. Albendazole-mebendazole and albendazole-oxantel pamoate have shown promising results in clinical trials. However,in vitroandin vivodrug interaction studies should be performed before their simultaneous treatment can be recommended. Inhibition of human recombinant cytochromes P450 (CYPs) CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 was tested by exposure to albendazole, albendazole sulfoxide, mebendazole, and oxantel pamoate, as well as albendazole-mebendazole, albendazole sulfoxide-mebendazole, albendazole-oxantel pamoate, and albendazole sulfoxide-oxantel pamoate. A high-pressure liquid chromatography (HPLC)-UV/visible spectroscopy method was developed and validated for simultaneous quantification of albendazole sulfoxide, albendazole sulfone, mebendazole, and oxantel pamoate in plasma. Albendazole, mebendazole, oxantel pamoate, albendazole-mebendazole, and albendazole-oxantel pamoate were orally applied to rats (100 mg/kg) and pharmacokinetic parameters calculated. CYP1A2 showed a 2.6-fold increased inhibition by albendazole-oxantel pamoate (50% inhibitory concentration [IC50] = 3.1 μM) and a 3.9-fold increased inhibition by albendazole sulfoxide-mebendazole (IC50= 3.8 μM) compared to the single drugs. In rats, mebendazole's area under the concentration-time curve (AUC) and maximal plasma concentration (Cmax) were augmented 3.5- and 2.8-fold, respectively (P= 0.02 for both) when coadministered with albendazole compared to mebendazole alone. Albendazole sulfone was slightly affected by albendazole-mebendazole, displaying a 1.3-fold-elevated AUC compared to albendazole alone. Oxantel pamoate could not be quantified, translating to a bioavailability below 0.025% in rats. Elevated plasma levels of albendazole sulfoxide, albendazole sulfone, and mebendazole in coadministrations are probably not mediated by CYP-based drug-drug interaction. Even though this study indicates that it is safe to coadminister albendazole-oxantel pamoate and albendazole-mebendazole, human pharmacokinetic studies are recommended.

Anthelmintic residues in goat and sheep dairy products

A multiresidue method (LC-MS/MS) for determination of wide range of anthelmintics was developed. The method covered benzimidazoles: albendazole (and metabolites), cambendazole, fenbendazol (and metabolites), flubendazole (and metabolites), mebendazole (and metabolites), oxibendazole, thiabendazole (and metabolites), triclabendazole (and metabolites); macrocyclic lactones: abamectin, doramectin, emamectin, eprinomectin, ivermectin, moxidectin; salicylanilides: closantel, ioxynil, nitroxynil, oxyclosamide, niclosamide, rafoxanid and others: clorsulon, derquantel, imidocarb, monepantel (and metabolites), morantel, praziquantel, and pyrantel. The method was used to examine the potential presence of anthelmintics in goat and sheep milk and dairy products from the Polish market. A total of 120 samples of milk, yoghurt, cottage cheese, cream cheese, and curd were analysed. None of the samples were found positive above CCα (1-10 μg/kg) except for one cottage cheese in which traces of albendazole sulfone were detected (5.2 ug/kg) and confirmed. The results of the study showed negligible anthelmintic residues in the goat and sheep milk and dairy products and confirm their good quality.

Simultaneous Determination of Benzimidazoles and Their Metabolites in Plasma Using High-Performance Liquid Chromatography/Tandem Mass Spectrometry: Application to Pharmacokinetic Studies in Rabbits

An HPLC/MS/MS method was developed for the simultaneous determination of the following benzimidazole anthelmintics and metabolites in plasma: flubendazole, albendazole, fenbendazole, mebendazole, thiabendazole, hydrolyzed flubendazole, albendazole sulfoxide, albendazole sulfone, albendazole aminosulfone, oxfendazole, fenbendazole sulfone, aminomebendazole, hydroxymebendazole, and 5-hydroxythiabendazole. The sample preparation process involved a pH-dependent extraction of the analytes. Chromatographic separation was performed on a C18 column with a mobile phase gradient starting with methanol–water (20 + 80, v/v) containing 0.1% formic acid. The overall average recoveries of the analytes based on a matrix-matched calibration ranged from 75.0 to 120.0%, with RSD values of &lt;20.0%. The LODs ranged from 0.08 to 2.0 μg/kg and the LOQs from 0.3 to 5.0 μg/kg. The validated method was used in pharmacokinetic studies of benzimidazole compounds in rabbits, and the elimination of the metabolites was measured quantitatively.