Determination of albendazole and its main metabolites in ovine plasma by liquid chromatography with dialysis as an integrated sample preparation technique

An Electrochemical Sensor for the Detection of Albendazole Using Glassy Carbon Electrode Modified with Platinum-Palladium Nanocomposites

An electroanalytical electrode for the detection of albendazole (ABZ) active ingredient in pharmaceutical dosage form and in contaminated animal-derived products was developed using a glassy carbon electrode modified with platinum-palladium nanoparticles. The electro-catalytic performance of the bimetallic-modified glassy carbon electrode was compared with its bare counterpart. Under optimized conditions, the modified electrode revealed two well-resolved anodic peak currents at 1.10 and 1.23 V using differential pulse voltammetry. Pure ABZ, as well as ABZ in spiked foods (milk and chicken), were detected with little interference from the food matrix. This electrode demonstrated high sensitivity and applicability, with a lower limit of detection of 0.08 µmol L^-1 in aqueous solution and 10 µmol L^-1 in the contaminated ground chicken and 100 µmol L^-1 in the contaminated milk sample. The fabricated sensor is low in cost and appropriate for the estimation of albendazole in tablet dosage forms and biological samples, and so can act as a quality control tool in the pharmaceutical and food industry.

Liquid chromatography--tandem mass spectrometry method for simultaneous determination of albendazole and albendazole sulfoxide in human plasma for bioequivalence studies

An improved high performance liquid chromatography--tandem mass spectrometry (LC–MS/MS) method has been developed for sensitive and rapid determination of albendazole (ABZ) and its active metabolite, albendazole sulfoxide (ABZSO), in the positive ionization mode. The method utilized solid phase extraction (SPE) for sample preparation of the analytes and their deuterated internal standards (ISs) from 100 µL human plasma. The chromatography was carried out on Hypurity C₁₈ column using acetonitrile-2.0 mM ammonium acetate, pH 5.0 (80:20, v/v) as the mobile phase. The assay exhibited a linear response over the concentration range of 0.200–50.0 ng/mL for ABZ and 3.00–600 ng/mL for ABZSO. The recoveries of the analytes and ISs ranged from 86.03%–89.66% and 89.85%–98.94%, respectively. Matrix effect, expressed as IS-normalized matrix factors, ranged from 0.985 to 1.042 for the both analytes. The method was successfully applied for two separate studies in healthy subjects using single dose of 400 mg conventional tablets and 400 mg chewable ABZ tablets, respectively.

Comparative plasma disposition kinetics of albendazole and its new benzimidazol prodrug in dog

The comparative pharmacokinetic behavior of albendazole (ABZ) and its new benzimidazol prodrug [1-tert-butyloxycarbonyl-5-propylthio-1-H-benzimidazol-2ylcarbamate of methyl] (ABZBoc), following their oral administration (10mg/kg) to healthy dogs was explored. Blood samples were obtained serially over a 24h period after treatment, then the plasma was analyzed by high-performance liquid chromatography (HPLC) to search the albendazole metabolites (ABZSO and ABZSO2). However, the albendazole parent drug was not detectable at any time after both treatments (ABZ and ABZBoc). By albendazole metabolites (ABZSO and ABZSO2) were the analytes recovered in the plasma after oral administration of ABZ and ABZBoc. Furthermore, some amounts of ABZBoc were also available in the plasma samples treated with this new produg. The plasma profile of each analyte followed a similar pattern after both treatments, the active metabolite (ABZSO) was the major analyte recovered in plasma (between 1 and 24h post-treatment). The pharmacokinetic parameters of both groups were calculated (Cmax, Tmax, t1/2, AUC0-›∞), and analyzed using the Student's t-test, P<0.05. Thus,the pharmacokinetic analysis indicated four statistically significant changes in the pharmacokinetic parameters defined above of the albendazole metabolites (ABZSO, ABZSO2) between the group treated with albendazole (group A) and that treated with ABZBoc prodrug (group B). Hence, the levels of the various pharmacokinetics parameters were low in the group treated with prodrug, as well they did not reach equivalent concentrations to that of albendazole. These differences between albendazole and its new prodrug may be explained by the fact that ABZBoc prodrug was not effectively reduced in the intestine of dogs.

Study on the interaction between albendazole and eosin Y by fluorescence, resonance Rayleigh scattering and frequency doubling scattering spectra and their analytical applications

In pH 3.25-3.35 Britton-Robinson (BR) buffer solution, albendazole (ABZ) could react with eosin Y (EY) to form a 1:1 ion-association complex, which not only results in the quenching of fluorescence, but also resulted in the great enhancement of resonance Rayleigh scattering (RRS) and frequency doubling scattering (FDS). Furthermore, a new RRS spectrum will appear, and the maximum RRS wavelength was located at about 356nm. The detection limit for ABZ were 21.51ng mL(-)(1) for the fluorophotometry, 6.93ng mL(-)(1) for the RRS method and 12.89ng mL(-)(1) for the FDS method. Among them, the RRS method had the highest sensitivity. The experimental conditions were optimized and effects of coexisting substances were evaluated. Meanwhile, the influences of coexisting substances were tested. The methods have been successfully applied to the determination of ABZ in capsules and human urine samples. The composition and structure of the ion-association complex and the reaction mechanism were discussed.

Review of methodology for the determination of benzimidazole residues in biological matrices

Benzimidazoles are anthelmintic agents widely used in the treatment of parasitic infections in a range of species and as fungicidal agents in the control of spoilage of crops during storage and transport. In this paper, the more important benzimidazoles are introduced and their pharmacological effects and physiochemical properties discussed. The metabolism of these drugs is described relating to the occurrence and persistence of residues in biological matrices, providing information for selection of suitable matrices and target residues for testing. Methods for determination of benzimidazoles are reviewed for a range of biological matrices. The importance of selecting suitable extraction and clean-up procedures is discussed, along with the difficulties encountered in adapting single residue methods to multi-residue methods. The importance of suitable detection systems for determination of benzimidazoles, namely, screening, HPLC, GC and confirmatory methods is described in detail. The future for benzimidazole residue analysis is discussed, focusing on selection of appropriate residues for screening methods and protocols for confirmation of benzimidazole residues.

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-SO2) and 12 ng/mL for albendazole 2-aminosulphone (ABZ-SO2NH2) has been developed. Analytes were extracted from alkalinized samples with ethyl acetate. Separation was carried out on a C18 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-SO2 and 85.3+/-0.7% for ABZ-SO2NH2, 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.

Simultaneous determination of albendazole and its major active metabolite in human plasma using a sensitive and specific liquid chromatographic–tandem mass spectrometric method

A method for the simultaneous determination of albendazole (ABZ) and its major active metabolite albendazole sulfoxide (ABZ-SO) was developed and validated. The analytes were extracted from plasma samples by liquid-liquid extraction and analyzed using liquid chromatography-tandem mass spectrometry with an electrospray ionization interface. Estazolam was used as the internal standard. The assay was linear in the concentration range 0.4-200 ng/ml for ABZ and 4.0-2000 ng/ml for ABZ-SO. The intra- and inter-run precision (R.S.D.), calculated from quality control (QC) samples was less than 7.1 and 9.4% for ABZ and ABZ-SO, respectively. The accuracy as determined from QC samples was within +/- 3% for the analytes. Recoveries of ABZ and ABZ-SO were greater than 77 and 53%, respectively, over the calibration curve range. The method developed was successfully applied to pharmacokinetic studies of ABZ and ABZ-SO after an oral dose of 400 mg albendazole to healthy volunteers.

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-SO2) and albendazole 2-aminosulphone (ABZ-SO2NH2) in sheep blood plasma has been developed. Plasma samples were extracted with ethyl acetate under alkaline conditions. Separation was achieved on a C18 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-SO2 and 4 ng/ml for ABZ-SO2NH2. 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-SO2 and 89.1 +/- 0.6% for ABZ-SO2NH2. The method was successfully applied to quantitatively determine the three albendazole metabolites in plasma samples collected from sheep that had been orally administered albendazole.

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 microm, reverse phase, Discovery RPamide C16 column with UV detection at 290 nm. The calibration graphs were linear in the range of 0.05- 1 microg/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.

Determination of albendazole and its major metabolites in the muscle tissues of Atlantic salmon, tilapia, and rainbow trout by high performance liquid chromatography with fluorometric detection

A liquid chromatographic procedure for the determination of albendazole ([5-(propylthio)-1H-benzimidazol-2yl]carbamic acid methyl ester) and its major metabolites, albendazole sulfoxide, albendazole sulfone, and albendazole-2- aminosulfone in rainbow trout, tilapia, and salmon muscle with adhering skin tissue is described. The muscle tissue samples are made alkaline with potassium carbonate and extracted with ethyl acetate. The extracts are further subjected to cleanup by utilizing a number of liquid-liquid extraction steps. After solvent evaporation, the residue is reconstituted in mobile phase and chromatographed. The chromatography is carried out on a reversed phase Luna C(18) column, using acetonitrile/methanol/buffer as a mobile phase and a fluorescence detector. The average recoveries from the fortified muscle tissue of the three fish species for albendazole (25-100 ppb), albendazole sulfoxide (15.5-62 ppb), albendazole sulfone (1-10 ppb), and albendazole-2- aminosulfone (10-100 ppb) were 94, 77, 82, and 67%, respectively. The average CV for each compound was < or =10%. The procedure was validated and then applied to the determination of albendazole and its three major metabolites in the muscle tissue of the three fish species obtained after orally dosing with albendazole.

Simultaneous liquid chromatography-tandem mass spectrometric determination of albendazole sulfoxide and albendazole sulfone in plasma

This paper describes a simple, fast, sensitive and reliable method for the simultaneous determination of albendazole sulfoxide (ASOX) and albendazole sulfone (ASON), the two most important metabolites of the drug albendazole (ABZ), in plasma samples using liquid chromatography and tandem mass spectrometry. After liquid-liquid extraction with dichloromethane, the two albendazole metabolites and the internal standard phenacetin were resolved in a CN column using the mobile phase methanol-water (4:6, v/v) acidified with 1% acetic acid. Detection by electrospray mass spectrometry was carried out in the positive ion mode. The method was linear up to 2500 and 250 ng/ml for ASOX and ASON, respectively, with mean recoveries of more than 85%. The precision and accuracy data, based on within- and between-day variations over 5 days, were lower than 15%. The quantitation limits of 0.5 and 5.0 ng/ml for ASON and ASOX are low enough for the method to be suitable for pharmacokinetic studies. Pharmacokinetic data obtained with the proposed method following oral administration of ABZ to a patient with neurocysticercosis are also reported.

HPLC assay for albendazole and metabolites in human plasma for clinical pharmacokinetic studies

A sensitive and selective HPLC chromatography method using UV detection (295 nm) was developed for the determination of albendazole, albendazole sulfoxide (ABZSO), and albendazole sulfone (ABZSO2) in human plasma. Albendazole, ABZSO, ABZSO2, and the internal standard, oxibendazole, were extracted from human plasma by loading onto a conditioned C(18) SPE cartridge, rinsing with 15% methanol, and eluting with 90% methanol. Samples were evaporated under a stream of nitrogen, reconstituted with mobile phase, 1.25% triethylamine in water-methanol-acetonitrile (72:15:13, v/v/v) (pH* 3.1), and injected onto a Waters muBondapak Phenyl 3.9 x 300 mm HPLC column. Mobile phase flow rate was 1.0 ml/min. The retention times of albendazole, ABZSO, ABZSO2, and the internal standard were approximately 24.4, 7.9, 13.4, and 11.3 min, respectively. Total run time was 30 min. The assay was linear for concentration ranges in human plasma of 20-600 ng/ml for albendazole, 20-1000 ng/ml for ABZSO, and 20-300 ng/ml for ABZSO2. The analysis of quality control samples demonstrated excellent precision. Coefficients of variation for albendazole (20, 400, 600 ng/ml) were 6.7, 8.1 and 7.0%; ABZSO (20, 400, 800 ng/ml) were 6.0, 8.5 and 5.9%; ABZSO2 (20, 150, 300 ng/ml) were 3.1, 3.9 and 2.3%, respectively. The method appears to be robust and has been applied to a pharmacokinetic study of albendazole in healthy volunteers.

Strategy for the development of automated methods involving dialysis and trace enrichment as on-line sample preparation for the determination of basic drugs in plasma by liquid chromatography

Among the sample preparation techniques, dialysis followed by clean-up and enrichment of the dialysate on a pre-column has proved to be a useful approach for the LC determination of drugs in plasma. By use of sample processors, like the ASTED system, such bioanalytical methods can be fully automated, the dialysis and trace enrichment steps being directly coupled to LC. In order to facilitate the development of such automated methods, a strategy based on a decision tree has been elaborated. After the selection of appropriate conditions for the LC analysis, the decision tree provides information about suggested starting conditions and guidelines for the optimisation of the most important parameters likely to influence analyte recovery and method selectivity. The plasma samples are dialysed on a cellulose acetate membrane in the static-pulsed mode and the dialysate is enriched on a trace enrichment pre-column packed with octadecyl silica or with a strong cation-exchange material. This decision tree is until now restricted to the analysis of basic drugs in plasma. In order to demonstrate the applicability of this method development strategy, an automated procedure based on the coupling of dialysis with trace enrichment has been developed for the LC determination of antifungal agents (clotrimazole, econazole and miconazole) in plasma.

Development and validation of an automated method for the liquid chromatographic determination of sotalol in plasma using dialysis and trace enrichment on a cation-exchange pre-column as on-line sample preparation

A fully automated method for the determination of sotalol in human plasma was developed, involving dialysis through a cellulose acetate membrane, clean-up and enrichment of the dialysate on a strong cation-exchange pre-column and subsequent liquid chromatographic (LC) analysis with UV detection. All sample handling operations were carried out by means of an ASTED system. Before starting dialysis, the trace enrichment column (TEC) was conditioned. The plasma sample, to which the internal standard (atenolol) was automatically added, was then loaded in the donor channel and was kept static while the dialysis liquid, consisting of 0.017 M acetic acid, was passed through the acceptor channel in successive pulses. After each pulse, the dialysate was dispensed onto the TEC. When dialysis was discontinued, the analytes were eluted from the TEC by the LC mobile phase by rotation of a switching valve and transferred to the analytical column packed with octyl silica. The LC mobile phase was a mixture of methanol and pH 7.0 phosphate buffer containing 1-octanesulfonate at a concentration of 7.5 x 10(-4) M (19:81; v/v). The UV detection was performed at 230 nm. The influence of several parameters of the dialysis and trace enrichment processes on analyte recovery and method selectivity was investigated. The method was then validated. The mean absolute recovery for sotalol was about 60%. The limit of quantitation was 25 ng/ml and R.S.D. for repeatability and intermediate precision obtained at a concentration level of 50 ng/ml were 4.3 and 5.8%, respectively.

Advances in sample preparation in electromigration, chromatographic and mass spectrometric separation methods

The quality of sample preparation is a key factor in determining the success of analysis. While analysis of pharmaceutically important compounds in biological matrixes has driven forward the development of sample clean-up procedures in last 20 years, today's chemists face an additional challenge: sample preparation and analysis of complex biochemical samples for characterization of genotypic or phenotypic information contained in DNA and proteins. This review focuses on various sample pretreatment methods designed to meet the requirements for the analysis of biopolymers and small drugs in complex matrices. We discuss the advances in development of solid-phase extraction (SPE) sorbents, on-line SPE, membrane-based sample preparation, and sample clean-up of biopolymers prior to their analysis by mass spectrometry.