LC-MS/MS method for simultaneous determination of diethylcarbamazine, albendazole and albendazole metabolites in human plasma: Application to a clinical pharmacokinetic study

Dual-emissive Eu(III)-functionalized metal-organic frameworks for visual, rapid, and intelligent sensing of albendazole and albendazole sulfoxide in animal-origin food

Albendazole (ABZ), a benzimidazole-based anthelmintic, is widely used to treat helminth infections. The extensive and improper use of ABZ may cause drug residues in animal-origin food and anthelmintics resistance, which potentially threaten human health. Meanwhile, albendazole sulfoxide (ABZSO), a metabolite of ABZ, also exhibits toxic effects. Therefore, the detection of ABZ and ABZSO in animal-derived food is significantly necessary. Herein, a dual-emission europium fluorescent sensor (EuUHC-30) was rationally designed and constructed. EuUHC-30 exhibits high selectivity and sensitivity towards ABZ and ABZSO with a detection limit of 0.10 and 0.13 μM, respectively. Furthermore, EuUHC-30 was successfully applied for quantification of ABZ and ABZSO in milk and pig kidney, which were verified by HPLC analysis. Moreover, a smartphone-assisted EuUHC-30 fluorescent paper sensor was fabricated for the practical determination of ABZ and ABZSO in real food. Overall, this work provides a visual, rapid, and intelligent method for the detection of ABZ and ABZSO in animal-origin food.

Pharmacokinetics of Moxidectin combined with Albendazole or Albendazole plus Diethylcarbamazine for Bancroftian Filariasis

Moxidectin (MOX) is a milbemycin endectocide recently approved by the U.S. FDA for the treatment of onchocerciasis in persons at least 12 years of age. MOX has been shown to have a good safety profile in recent clinical trials. The efficacy of MOX for the treatment of lymphatic filariasis (LF) and its potential use in mass drug administration protocols for the elimination of LF is currently under evaluation. In the context of a clinical trial, we investigated the pharmacokinetics and drug interactions of a combination of MOX plus albendazole (ALB) with or without diethylcarbamazine (DEC) compared to ivermectin (IVM) plus ALB with or without DEC in the following four different treatment arms: (I) IVM (0.2mg/kg) plus DEC (6 mg/kg) and ALB (400mg); (II) IVM plus ALB; (III) MOX (8 mg) plus DEC and ALB; and (IV) MOX plus ALB. Drug concentrations were determined using validated liquid chromatography-mass spectrometric methods. Pharmacokinetic parameters were determined using standard non-compartmental analysis methods. Statistical analysis was performed using JMP software. Fifty-eight of 164 study participants (53 men and five women) were included with ages ranging from 18 to 63 yrs (mean = 37). MOX apparent oral clearance (Cl/F) ranged from 0.7 to 10.8 L/hr with Cmax values ranging from 20.8 to 314.5 ng/mL. The mean (range) area under the curve (AUC)0-∞ for MOX, 3405 ng*hr/mL (742-11376), and IVM 1906 ng*hr/mL (692-5900), varied over a ~15.3 and ~8.5-fold range, respectively. The geometric mean ratio for Cmax, AUC0-t, and AUC0-∞ were within the no-drug interaction range of 80-125% for all drugs. This indicates that the addition of MOX to ALB alone or ALB plus DEC for LF therapy did not alter the drug exposure of co-administered drugs compared to IVM combinations. Clinical Trial Registration: NCT04410406, https://clinicaltrials.gov/.

Population pharmacokinetic model of ivermectin in mass drug administration against lymphatic filariasis

BACKGROUND

Ivermectin (IVM) is a broad-spectrum anthelmintic drug used to treat diseases caused by filarial worms, such as onchocerciasis and lymphatic filariasis (LF). IVM is part of a triple-drug therapy used by the Mass Drug Administration (MDA) as a preventive strategy to eradicate LF in sub-Saharan Africa. The drug shows high variability in drug exposure in previous pharmacokinetic studies. This study aims to build a population pharmacokinetic (PopPK) model to identify and quantify the possible sources of the variability of IVM exposure after a single-oral dose in LF-infected subjects and healthy individuals.

METHODOLOGY / PRINCIPAL FINDINGS

In this analysis, 724 samples were collected from treatment-naïve Wuchereria bancrofti-infected (n = 32) and uninfected (n = 24) adults living in Côte d'Ivoire who had received one dose of IVM as a part of triple-drug therapy. PopPK analysis was conducted using Phoenix NLME 8.3 software. The Monte Carlo simulation based on the final model was performed to simulate drug exposure among different dosing groups (200 μg/kg, 18 mg, and 36 mg). A two-compartment model with zero-order dose input into the absorption compartment with a lag time function followed by first-order absorption and linear elimination best described the IVM's pharmacokinetic (PK) parameters. The final model identifies that the PK parameters of IVM are not affected by LF infection. Sex was a significant covariate on the peripheral volume of distribution (Vp/F, 53% lower in men than in women). IVM drug exposure shows linear pharmacokinetic behavior among the simulated dosing groups with similar drug exposure based on sex.

CONCLUSION/SIGNIFICANCE

We have developed a PopPk model to describe and identify possible sources of the variability of IVM exposure. To our knowledge, this is the first PopPK study of IVM in patients with LF.

TRIAL REGISTRATION

NCT02845713; NCT03664063.

Novel albendazole-glucan particles for enhancing intestinal absorption and improving hepatic targeting

Background

Glucan particles (GPs) are derived from the Saccharomyces cerevisiae cell wall. The hollow particles composed of β-1,3-D-glucan have been extensively studied in terms of immune regulation and macrophage-targeted drug delivery. Albendazole (ABZ) is a benzimidazole drug with good anti-parasitic activity and is the drug recommended by the World Health Organization for the first-line treatment of hydatid disease.

Methods

A dynamic light scatterometer, scanning electron microscope, and transmission electron microscope were used to characterize the ABZ-GPs. High-performance liquid chromatography (HPLC), laser scanning confocal microscope (LSCM) and an in vivo small animal imaging system were used to evaluate theability of ABZ-GPs to be recognized by macrophages, whether ABZ-GPs are more readily absorbed and eliminated in the blood than the original ABZ drug in rats, and the ability of ABZ-GPs to target the mouse liver.

Results

The ABZ-GPs were successfully constructed to achieve fluorescence, magnetic resonance imagining, and laser confocal microscopy imaging. The glucan shell effectively protects ABZ from enzymatic degradation and from being pumped out in the gastrointestinal tract. The analysis of ABZ and its major metabolite albendazole sulfoxide in the rat plasma and mouse liver showed that compared to the ABZ suspension group, the degradation of ABZ-GPSs in the blood was low, and the targeting of ABZ-GPSs in the liver was significantly enhanced.

Conclusions

In the oral treatment of hepatic hydatid disease, GPs can be used as carriers to achieve the targeted transport of ABZ, which in turn can be used for the targeted therapy of liver echinococcosis. Thus, ABZ-GPs may be a promising form of targeted therapy.

Factors associated with variation in single-dose albendazole pharmacokinetics: A systematic review and modelling analysis

BACKGROUND

Albendazole is an orally administered anti-parasitic medication with widespread usage in a variety of both programmatic and clinical contexts. Previous work has shown that the drug's pharmacologically active metabolite, albendazole sulfoxide, is characterised by substantial inter-individual pharmacokinetic variation. This variation might have implications for the efficacy of albendazole treatment, but current understanding of the factors associated with this variation remains incomplete.

METHODOLOGY/PRINCIPAL FINDINGS

We carried out a systematic review to identify references containing temporally disaggregated data on the plasma concentration of albendazole and/or (its pharmacologically-active metabolite) albendazole sulfoxide following a single oral dose. These data were then integrated into a mathematical modelling framework to infer albendazole sulfoxide pharmacokinetic parameters and relate them to characteristics of the groups being treated. These characteristics included age, weight, sex, dosage, infection status, and whether patients had received a fatty meal prior to treatment or other drugs alongside albendazole. Our results highlight a number of factors systematically associated with albendazole sulfoxide pharmacokinetic variation including age, existing parasitic infection and receipt of a fatty meal. Age was significantly associated with variation in albendazole sulfoxide systemic availability and peak plasma concentration achieved; as well as the clearance rate (related to the half-life) after adjusting for variation in dosage due to differences in body weight between children and adults. Receipt of a fatty meal prior to treatment was associated with increased albendazole sulfoxide systemic availability (and by extension, peak plasma concentration and total albendazole sulfoxide exposure following the dose). Parasitic infection (particularly echinococcosis) was associated with altered pharmacokinetic parameters, with infected populations displaying distinct characteristics to uninfected ones.

CONCLUSIONS/SIGNIFICANCE

These results highlight the extensive inter-individual variation that characterises albendazole sulfoxide pharmacokinetics and provide insight into some of the factors associated with this variation.

Assessing the efficacy of albendazole against hookworm in Vietnam using quantitative PCR and sodium nitrate flotation

Preventive chemotherapy (PC), consisting of the regular distribution of anthelmintics to populations or groups of populations at risk, is the primary tool used to control soil-transmitted helminth (STH) infections. This strategy, whilst cost-effective, raises the concern of potential emergence of drug resistance. The efficacy of anthelmintics against STH infections is measured using cure rate (CR) and egg reduction rate (ERR), using microscopy-based techniques such as the Kato-Katz thick smear. However, Kato-Katz has low sensitivity, especially for low-intensity infections, and requires fresh samples that need to be processed quickly. Realtime quantitative PCR (qPCR), which is more sensitive, is emerging as a "gold standard" for STH diagnostics given its higher sensitivity (important in low prevalence settings) and ability to differentiate hookworm species, while sodium nitrate flotation (SNF) may provide a low-cost more sensitive and practical alternative to Kato-Katz in the field. In this study, we examined the efficacy of a locally manufactured brand of albendazole 400 mg ("Alzental") against hookworm in Đắk Lắk province, Vietnam, using both qPCR and SNF. For qPCR, formulae to convert qPCR cycle threshold (Ct) values into eggs per gram of faeces (EPG) were utilised to determine efficacy calculations, and these values directly compared with efficacy values generated using SNF. Factors associated with CR and ERR were examined, and Alzental tablet quality was assessed by comparing with an Australian TGA-approved equivalent "Eskazole" tablet. We observed a CR and ERR of 64.9% and 87.5% respectively using qPCR, and 68.4% and 67.6% respectively using SNF. The tablet composition of Alzental was comparable to Eskazole in terms of active albendazole drug concentration with no evidence of impurities. This study demonstrates that the efficacy of Alzental against hookworm is within the range of previously reported studies for albendazole 400 mg. The study also demonstrates the value of qPCR and SNF as alternatives to standard Kato-Katz methodology for assessment of anthelmintic efficacy.

Population pharmacokinetics of diethylcarbamazine in patients with lymphatic filariasis and healthy individuals

Diethylcarbamazine (DEC) is a drug of choice to treat lymphatic filariasis (LF) either used alone or in combination as mass drug administration (MDA) preventive strategies. The objective of this study was to develop a population pharmacokinetic model for DEC in subjects infected with lymphatic filariasis (LF) compared to healthy individuals, and to evaluate the effect of covariates on the volume of distribution (V/F) and oral clearance (CL/F) of DEC. This was an open-label cohort study of treatment naïve Wuchereria bancrofti-infected (n=32) and uninfected (n=24) adults residing in the Agboville district of Côte d'Ivoire. The population pharmacokinetic model for DEC was built using Phoenix NLME 8.0 software. The covariates included in the model building process were age, gender, bodyweight, infection status, creatinine clearance (CrCl), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. A total of 56 adults were enrolled in the study and a total of 728 samples were obtained over 168 hours. A one-compartment linear pharmacokinetic model with first-order absorption with an absorption lag-time (Tlag) best described the data. After determining the pharmacokinetics (PK) parameters of DEC, body weight and gender were found to be the significant covariates for DEC V/F. The final population pharmacokinetic model adequately described the pharmacokinetics of DEC in the studied population. Model-based simulation indicated that the body weight significantly impacted the exposure in both the male and female population. This analysis may further support the drug-drug interaction model development of DEC with different co-administered drugs/agents in disease control programs.

Plasmodium falciparum phenotypic and genotypic resistance profile during the emergence of Piperaquine resistance in Northeastern Thailand

Malaria remains a public health problem in Thailand, especially along its borders where highly mobile populations can contribute to persistent transmission. This study aimed to determine resistant genotypes and phenotypes of 112 Plasmodium falciparum isolates from patients along the Thai-Cambodia border during 2013-2015. The majority of parasites harbored a pfmdr1-Y184F mutation. A single pfmdr1 copy number had CVIET haplotype of amino acids 72-76 of pfcrt and no pfcytb mutations. All isolates had a single pfk13 point mutation (R539T, R539I, or C580Y), and increased % survival in the ring-stage survival assay (except for R539I). Multiple copies of pfpm2 and pfcrt-F145I were detected in 2014 (12.8%) and increased to 30.4% in 2015. Parasites containing either multiple pfpm2 copies with and without pfcrt-F145I or a single pfpm2 copy with pfcrt-F145I exhibited elevated IC₉₀ values of piperaquine. Collectively, the emergence of these resistance patterns in Thailand near Cambodia border mirrored the reports of dihydroartemisinin-piperaquine treatment failures in the adjacent province of Cambodia, Oddar Meanchey, suggesting a migration of parasites across the border. As malaria elimination efforts ramp up in Southeast Asia, host nations militaries and other groups in border regions need to coordinate the proposed interventions.

New and sensitive HPLC-UV method for concomitant quantification of a combination of antifilariasis drugs in rat plasma and organs after simultaneous oral administration

A combination treatment comprising ivermectin (IVM), albendazole (ABZ) and doxycycline (DOX) is often prescribed for lymphatic filariasis patients. Nevertheless, there has not been an analytical method established and documented to determine these compounds simultaneously. Herein, we report a new high-performance liquid chromatographic method coupled with a UV detector (HPLC-UV) to quantify these drugs in plasma and organs. This developed analytical method was validated according to the International Conference on Harmonization (ICH) and US Food and Drug Administration (FDA) guidelines. The validated method was successfully employed to analyze IVM, ABZ along with its metabolites (albendazole sulfoxide (ABZ-OX) and albendazole sulfone (ABZ-ON)), and DOX in the plasma and organs of Wistar rats after simultaneous oral administration. An Xselect CSH™ C₁₈ HPLC column was utilized as a stationary phase, with a mobile phase consisting of 0.1% v/v trifluoracetic acid in water and acetonitrile with a run time of 20 min. The calibration curves in biological samples were found to be linear across the concentration range of 0.01-5 μg mL^-1 for IVM, ABZ and ABZ metabolites, and 0.025-10 μg mL^-1 for DOX with an R value ≥0.998 in each case. The validated method was found to be selective, precise and accurate. Finally, the method developed in this study was deployed to assess the pharmacokinetic profiles and biodistribution of the combination of drugs after oral administration to Wistar rats. The validated HPLC-UV method in this study provides an extensive range of prospective applications for pharmacokinetic-based studies, therapeutic drug monitoring and toxicology.

A new approach for microextraction of trace albendazole sulfoxide drug from the samples of human plasma and urine, and water by the molecularly imprinted polymer nanoparticles combined with HPLC

In this research study, a method of dispersive-micro-solid phase extraction (D-µ-SPE) combined with molecularly imprinted polymer nanoparticles (MIP-NPs) with HPLC-UV was developed for the fast and selective detection of the trace amount of albendazole sulfoxide (ABZSO) in the biological samples. To investigate the effective factors on ABZSO microextraction by the method, central composite design (CCD) was utilized, and the optimum conditions for ABZSO microextraction were sample pH of 8.0, MIP-mass of 15 mg, sonication time of 12 min, and eluent (methanol) volume of 0.25 mL. Under the obtained optimal extraction conditions, the value for the limit of detection (LOD) and limit of quantification (LOQ) was respectively showed to be 0.074 and 0.246 ng mL^-1. In addition, the calculated peak areas exhibited a linear relationship with the ABZSO concentration ranging from 0.4 to 4200 ng mL^-1. The analyses of the samples including human plasma and urine, and water were successfully performed by the usage of the D-µ-SPE method, which was a simple and sensitive technique and a suitable alternative for the analysis of ABZSO. In the analysis of ABZSO in various samples, the recoveries at various levels of ABZSO concentrations (50, 300, and 500 ng mL^-1) were in the range of 95.7-103.0 %, and the relative standard deviations (RSDs; n = 3) varied from 2.2 to 4.4%.

Diethylcarbamazine activates TRP channels including TRP-2 in filaria, Brugia malayi

Diethylcarbamazine is an important classic drug used for prevention and treatment of lymphatic filariasis and loiasis, diseases caused by filarial nematodes. Despite many studies, its site of action has not been established. Until now, the consensus has been that diethylcarbamazine works by activating host immune systems, not by a direct action on the parasites. Here we show that low concentrations of diethylcarbamazine have direct and rapid (<30 s) temporary spastic paralyzing effects on the parasites that lasts around 4 h, which is produced by diethylcarbamazine opening TRP channels in muscle of Brugia malayi involving TRP-2 (TRPC-like channel subunits). GON-2 and CED-11, TRPM-like channel subunits, also contributed to diethylcarbamazine responses. Opening of these TRP channels produces contraction and subsequent activation of calcium-dependent SLO-1K channels. Recovery from the temporary paralysis is consistent with inactivation of TRP channels. Our observations elucidate mechanisms for the rapid onset and short-lasting therapeutic actions of diethylcarbamazine.

Determination of 19 anthelmintics in environmental water and sediment using an optimized PLE and SPE method coupled with UHPLC-MS/MS

A sensitive quantification method using pressurized liquid extraction (PLE) and solid phase extraction (SPE) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for determination of 19 anthelmintic drugs (ADs) belonging to seven structural groups (Benzimidazoles, Diphenylsulfides, Imidazothiazoles, Hexahydropyrazines, Macrocylic lactones, Salicylanilides, Tetrahydropyrimidines) in environmental water and sediment samples. Eleven SPE cartridges, sample pH, elution solvents were tested to determine the optimal conditions for extraction. Among these investigated SPE types, the best recoveries for 19 target ADs were obtained from Oasis HLB cartridge with 37-102%, 45-103%, 37-88%, 28-82% and 31-90% for spiked river water, tap water, rainwater, wastewater, and sediment respectively (with RSD < 15%), except for closantel. The 19 ADs were separated within 10 min by a BEH C18 column and monitored in both positive and negative ions modes with switching electrospray ionization source. The cross-talk interferences were solved by identification of secondary mass spectrum of substances through MRM-IDA-EPI scanning using Qtrap. These interference peaks could be efficiently eliminated by setting MRM segments or using Qtrap to obtain tertiary fragmented information. The developed methods were satisfactory in terms of linearity, accuracy, and precision, and used eight isotopically labeled compounds as internal standards to correct matrix effects. Method quantification limit (MQL) for 19 ADs was below 1.1 ng/L, 0.4 ng/L, 5.4 ng/L and 2.3 ng/g for river water, tap water, wastewater, and sediment, respectively. The validated method was successfully used to investigate the occurrence of anthelmintics in water and sediment samples from Chengdu, China. All ADs were detected in environment with the concentrations at ng/L level.

Development and application of a urine drug concentration method for the evaluation of oral absorption of ibandronate in clinical patients

Aim: A urine drug concentration method was developed for the evaluation of oral ibandronte absorption based on the fact that ibandronate is excreted unchanged by the kidneys. Methodology: Ibandronate was isolated from the urine matrix by coprecipitated with 2.5 M CaCl₂ and 1 M K₂HPO₄ in basic conditions. After a liquid-liquid extraction, the analytes were derivatized with trimethylsilydiazomethane prior to detection. Results: The calibration curves exhibited excellent linearity (r > 0.99) between 1 and 250 ng/ml in human urine. Ibandronate was recovered >86.5% with the inter- and intraday relative standard deviations less than 15%. Conclusion: The method is selective, accurate, practical and was successfully applied to study the influence of vitamin D₃ on the absorption of ibandronate.

Rapid screening of nine unradiolabeled candidate compounds as PET brain imaging agents using cassette-wave microdosing and LC-MS/MS

The R&D of PET imaging agents is a complex system engineering, simplifying screening steps and increasing screening efficiency have become popular issues. The purpose of this study is to develop a new screening procedure using cassette-wave microdosing and LC-MS/MS to enhance the screening throughput of unradiolabeled candidate compounds as PET imaging agents. Nine compounds were divided into 3 sets and made into 3 cassettes. Fifteen rats were randomly divided into 3 groups, and every animal received three intravenous bolus injections at three different time points; the doses were at microdose levels. This dosing approach takes advantage of temporal and spatial differences and is likened to an input wave; therefore, this approach was named cassette-wave microdosing. The samples of different brain regions such as the hypothalamus, striatum, hippocampus, cortex, cerebellum and the remainder of the brain were detected by LC-MS/MS analysis. The research potential of the compounds as PET imaging agents is evaluated in terms of brain biodistribution data. The screening method is rapid, highly efficient, reliable and reduces animal usage. Additionally, it can shorten the evaluation process of radiopharmaceuticals and enhance the screening throughput of PET radiopharmaceuticals without the use of radioactive agents.

Pharmacokinetics, safety, and efficacy of a single co-administered dose of diethylcarbamazine, albendazole and ivermectin in adults with and without Wuchereria bancrofti infection in Côte d'Ivoire

Background

A single co-administered dose of ivermectin (IVM) plus diethylcarbamazine (DEC) plus albendazole (ALB), or triple-drug therapy, was recently found to be more effective for clearing microfilariae (Mf) than standard DEC plus ALB currently used for mass drug administration programs for lymphatic filariasis (LF) outside of sub-Saharan Africa. Triple-drug therapy has not been previously tested in LF-uninfected individuals from Africa. This study evaluated the pharmacokinetics (PK), safety, and efficacy of triple-drug therapy in people with and without Wuchereria bancrofti infection in West Africa.

Methods

In this open-label cohort study, treatment-naïve microfilaremic (>50 mf/mL, n = 32) and uninfected (circulating filarial antigen negative, n = 24) adults residing in Agboville district, Côte d’Ivoire, were treated with a single dose of IVM plus DEC plus ALB, and evaluated for adverse events (AEs) until 7 days post treatment. Drug levels were assessed by liquid chromatography and mass spectrometry. Persons responsible for assessing AEs were blinded to participants’ infection status.

Findings

There was no difference in AUC_0-inf or C_max between LF-infected and uninfected participants (P>0.05 for all comparisons). All subjects experienced mild AEs; 28% and 25% of infected and uninfected participants experienced grade 2 AEs, respectively. There were no severe or serious adverse events. Only fever (16 of 32 versus 4 of 24, P<0.001) and scrotal pain/swelling in males (6 of 20 versus 0 of 12, P = 0.025) were more frequent in infected than uninfected participants. All LF positive participants were amicrofilaremic at 7 days post-treatment and 27 of 31 (87%) remained amicrofilaremic 12 months after treatment.

Conclusions

Moderate to heavy W. bancrofti infection did not affect PK parameters for IVM, DEC or ALB following a single co-administered dose of these drugs compared to uninfected individuals. The drugs were well tolerated. This study confirmed the efficacy of the triple-drug therapy for clearing W. bancrofti Mf and has added important information to support the use of this regimen in LF elimination programs in areas of Africa without co-endemic onchocerciasis or loiasis.

Trial registration

ClinicalTrials.gov NCT02845713.

Lymphatic filariasis is a mosquito-borne infection that causes disability in the form of lymphedema, hydroceles, and elephantiasis. It has been targeted for global elimination based on mass drug administration in the total population at risk including many people uninfected with LF. Recently, a single co-administered dose of IVM + DEC + ALB has been shown to be much more effective than the standard treatment with DEC + ALB for sustained clearance of Mf for 3 years based on studies in Papua New Guinea. This study confirms the efficacy and safety of triple-drug therapy for clearing of Wuchereria bancrofti Mf in an African population. The presence of LF did not affect drug levels and the medicines were well tolerated, with 28% and 25% rate of moderate AEs in infected and uninfected individuals respectively, and no severe or serious AEs, supporting the use of triple-drug therapy for mass drug administration. This study shows for the first time that triple-drug therapy also has a potent macrofilaricidal effect, as determined by the reduction in circulating filarial antigen and inactivation of worm nests one year following treatment.

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

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 (t _1/2 = ∼1.5 h), time to reach the maximum concentration (t _max = ∼2 h), and maximum concentration (C _max = 12.5 to 26.5 ng/ml) of albendazole were observed in the four matrices. The metabolites reached C _max after ∼4 h with a t _1/2 of ca. 7 to 8 h. A statistically significant difference in albendazole sulfone's t _1/2 as determined by using DBS and wet samples was detected. C _max of albendazole sulfoxide (288 to 380 ng/ml) did not differ among the matrices, but higher C _max 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.

A sensitive and selective LC-MS/MS method for quantitation of ivermectin in human, mouse and monkey plasma: clinical validation

Aim: A sensitive and selective LC-MS/MS method was validated for quantitation of ivermectin (IVM) in plasma. Method: The IVM was extracted from plasma using solid-phase extraction with C-18 cartridges. Separation of analytes was achieved on an ACE C18 column with isocratic elution using 0.1% acetic acid and methanol: acetonitrile (1:1, v/v) as mobile phase. The IVM was quantitated using electrospray ionization operating in negative multiple reaction monitoring mode. Results: The MS/MS response was linear over the concentration range from 0.1-1000 ng/ml. The method for human plasma was validated as per US FDA guidelines. The LC-MS/MS method is sensitive, reproducible, has easy sample preparation and is suitable for IVM quantitation in clinical samples.

Case Report: Ivermectin and Albendazole Plasma Concentrations in a Patient with Disseminated Strongyloidiasis on Extracorporeal Membrane Oxygenation and Continuous Renal Replacement Therapy

Disseminated strongyloidiasis is often fatal, despite treatment with oral albendazole and parenteral ivermectin (IVM). Here, we report elevated plasma IVM and albendazole sulfoxide concentrations in the context of extracorporeal membrane oxygenation and continuous renal replacement therapy in a patient with disseminated strongyloidiasis treated with subcutaneous IVM and nasogastric albenzadole. Despite elevated drug plasma concentrations, live filariform larvae were detected in endotracheal aspirates after 2 weeks of treatment.