Albendazole kinetics in patients with echinococcosis: delayed absorption and impaired elimination in cholestasis

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.

Pulmonary Echinococcosis or Lung Hydatidosis: A Narrative Review

Background: Lung hydatidosis is a zoonosis related to infection by the Echinococcus tapeworm species. Lung involvement in this condition is second only to the liver echinococcosis. Diagnosis ordinarily results from an accidental finding in a direct chest radiograph evaluation because of the delayed growth of the cysts. Moreover, a consistent treatment regimen or approach may not be feasible because of the variability of pulmonary echinococcosis. In this review, we expect to sum up the main features of lung hydatidosis with a perspective on medical and surgical treatment. Methods: Cochrane Library and PubMed were the databases used to perform a narrative literature review. Search terms included "pulmonary echinococcosis" and "lung hydatidosis." The MeSH terms were "lung" [All Fields] AND {"echinococcosis" [MeSH Terms] OR ("hydatidosis" [All Fields] OR "pulmonary" [All Fields] AND "echinococcosis" [All Fields] OR "hydatidosis." A search period from September 1980 to May 2020 was chosen to compare studies from different decades, given the changes in pulmonary echinococcosis management. Results: A uniform treatment regimen or approach may not be feasible because of the variability of pulmonary echinococcosis. No clinical trials have analyzed and compared all the diverse treatment approaches. Cyst size, characteristics, position in the lung and clinical presentation, and the availability of medical/surgical expertise and equipment are the mainstays of echinococcosis management. When feasible, surgery is as yet the principal therapeutic choice to eliminate the cysts; anti-parasitic drugs may minimize complications during high-risk surgery or be used as definitive therapy in some instances with contraindications to surgery. Conclusions: Lung hydatidosis management must become less heterogeneous. We support treatment directed to the subject established on the clinical scenario, host factors, and surgical risk. Strict cooperation in this process between infectious disease specialists and surgeons may optimize best practices to help create shared practical guidelines to simplify clinicians' decision-making. Furthermore, we need a consensus for lung hydatidosis treatment and inserting this disease to global surgery agenda will have a positive impact on acquiring high-quality data that enables us to create an evidence-based guideline for this disease.

Metformin Suppresses Development of the Echinococcus multilocularis Larval Stage by Targeting the TOR Pathway

Alveolar echinococcosis (AE) is a severe disease caused by the larval stage of the tapeworm Echinococcus multilocularis Current chemotherapeutic treatment options based on benzimidazoles are of limited effectiveness, which underlines the need to find new antiechinococcosis drugs. Metformin is an antihyperglycemic and antiproliferative agent that shows activity against the related parasite Echinococcus granulosus Hence, we assessed the in vitro and in vivo effects of the drug on E. multilocularis Metformin exerted significant dose-dependent killing effects on in vitro cultured parasite stem cells and protoscoleces and significantly reduced the dedifferentiation of protoscoleces into metacestodes. Likewise, oral administration of metformin (50 mg/kg of body weight/day for 8 weeks) was effective in achieving a significant reduction of parasite weight in a secondary murine AE model. Our results revealed mitochondrial membrane depolarization, activation of Em-AMPK, suppression of Em-TOR, and overexpression of Em-Atg8 in the germinal layer of metformin-treated metacestode vesicles. The opposite effects on the level of active Em-TOR in response to exogenous insulin and rapamycin suggest that Em-TOR is part of the parasite's insulin signaling pathway. Finally, the presence of the key lysosomal pathway components, through which metformin reportedly acts, was confirmed in the parasite by in silico assays. Taken together, these results introduce metformin as a promising candidate for AE treatment. Although our study highlights the importance of those direct mechanisms by which metformin reduces parasite viability, it does not necessarily preclude any additional systemic effects of the drug that might reduce parasite growth in vivo.

Lack of Clinical Pharmacokinetic Studies to Optimize the Treatment of Neglected Tropical Diseases: A Systematic Review

INTRODUCTION

Neglected tropical diseases (NTDs) affect more than one billion people, mainly living in developing countries. For most of these NTDs, treatment is suboptimal. To optimize treatment regimens, clinical pharmacokinetic studies are required where they have not been previously conducted to enable the use of pharmacometric modeling and simulation techniques in their application, which can provide substantial advantages.

OBJECTIVES

Our aim was to provide a systematic overview and summary of all clinical pharmacokinetic studies in NTDs and to assess the use of pharmacometrics in these studies, as well as to identify which of the NTDs or which treatments have not been sufficiently studied.

METHODS

PubMed was systematically searched for all clinical trials and case reports until the end of 2015 that described the pharmacokinetics of a drug in the context of treating any of the NTDs in patients or healthy volunteers.

RESULTS

Eighty-two pharmacokinetic studies were identified. Most studies included small patient numbers (only five studies included >50 subjects) and only nine (11 %) studies included pediatric patients. A large part of the studies was not very recent; 56 % of studies were published before 2000. Most studies applied non-compartmental analysis methods for pharmacokinetic analysis (62 %). Twelve studies used population-based compartmental analysis (15 %) and eight (10 %) additionally performed simulations or extrapolation. For ten out of the 17 NTDs, none or only very few pharmacokinetic studies could be identified.

CONCLUSIONS

For most NTDs, adequate pharmacokinetic studies are lacking and population-based modeling and simulation techniques have not generally been applied. Pharmacokinetic clinical trials that enable population pharmacokinetic modeling are needed to make better use of the available data. Simulation-based studies should be employed to enable the design of improved dosing regimens and more optimally use the limited resources to effectively provide therapy in this neglected area.

Novel albendazole-chitosan nanoparticles for intestinal absorption enhancement and hepatic targeting improvement in rats

To improve the treatment of helminthiasis, filariasis, and colorectal cancer, albendazole-associated chitosan nanoparticles (ABZ-CS-NPs) were prepared using the emulsion crosslinking volatile technique with contained sodium tripolyphosphate as the crosslinking agent and Poloxamer 188 as the auxiliary solvent. The structural characteristics of the NPs were determined using X-ray diffraction to analyze the interaction between CS and the drug. The NPs were then evaluated in terms of their physicochemical characteristics, drug release behavior, in vivo pharmacokinetic parameters, and biodistribution in animal studies. ABZ-loaded NPs with a uniformly spherical particle sizes (157.8 ± 2.82 nm) showed efficient drug loading, encapsulated efficiency, and high physical stability. The drug release from ABZ-CS-NPs was extended over several periods. Kinetic models were then fitted to determine the release mechanisms. ABZ and its metabolite albendazole sulfoxide (ABZSX) were analyzed in rats with mebendazole as the internal standard using reversed-phase high-performance liquid chromatography. Compared with the ABZ suspension groups, the relative bioavailability values of ABZ and ABZSX were 146.05 and 222.15%, respectively. In addition, the plasma concentration versus time curve is consistent with that of the two compartment models in the plasma concentration versus time curve. The results indicate that the ABZ-loaded NPs are promising novel ABZ candidates for passive diffusion in the treatment of hydatid cysts in the liver via oral administration.

Anthelminthic treatment: an adjuvant therapeutic strategy against Echinococcus granulosus

The main goal of the paper is to clarify anthelminthic treatment as an alternative hydatic cyst therapy, its indications and contraindications. Chemotherapy constitutes a non-invasive treatment and is less limited by the patient's status than surgery or PAIR. Many investigators have employed benzoimidazole carbonates for the management of human hydatid disease. Both, albendazole and mebendazole have, a favourable effect in patients suffering from multiorgan and multicystic disease, in inoperable primary liver or lung echinococcosis, and they can also prevent secondary echinococcosis. Chemotherapy is contraindicated for large cysts that are at risk to rupture and for inactive or calcified cysts. The main adverse events are related to changes in liver enzyme levels. The best efficacy is observed with liver, lung, and peritoneal cysts. Certain various factors influence the therapeutic results of medical treatment. The vast majority of the recurring cysts show good susceptibility to re-treatment.

Enantioselective renal excretion of albendazole metabolites in patients with neurocysticercosis

The present study investigates the urinary excretion of the enantiomers of (+)- and (-)-albendazole sulfoxide (ASOX) and albendazole sulfone (ASON) in 12 patients with neurocysticercosis treated with albendazole for 8 days (7.5 mg/kg/12 h). Serial blood samples (0-12 h) and urine (three periods of 8 h) were collected after administration of the last dose of albendazole. Plasma and urine (+)-ASOX, (-)-ASOX, and ASON metabolites were determined by HPLC using a chiral phase column (Chiralpak AD) with fluorescence detection. The pharmacokinetic parameters (P < 0.05) for (+)-ASOX, (-)-ASOX, and ASON metabolites are reported as means (95% CI); amount excreted (Ae) = 3.19 (1.53-4.85) vs. 0.72 (0.41-1.04) vs. 0.08 (0.03-0.13) mg; plasma concentration-time area under the curve, AUC(0-24) = 3.56 (0.93-6.18) vs. 0.60 (0.12-1.08) vs. 0.38 (0.20-0.55) microg x h/ml, and renal clearance Cl(R) = 1.20 (0.66-1.73) vs. 2.72 (0.39-5.05) vs. 0.25 (0.13-0.37) l/h. Sulfone formation capacity, expressed as the Ae ratio ASON/ASOX + ASON, was 2.21 (1.43-2.99). These data point to enantioselectivity in the renal excretion of ASOX as a complementary mechanism to the metabolism responsible for the plasma accumulation of (+)-ASOX. The results also suggest that the metabolite ASON is partially eliminated as a reaction product of the subsequent metabolism.

Enantioselective distribution of albendazole metabolites in cerebrospinal fluid of patients with neurocysticercosis

AIMS

Albendazole (ABZ) is effective in the treatment of neurocysticercosis. ABZ undergoes extensive metabolism to (+) and (-)-albendazole sulphoxide (ASOX), which are further metabolized to albendazole sulphone (ASON). We have investigated the distribution of (+)-ASOX (-)-ASOX, and ASON in cerebrospinal fluid (CSF) of patients with neurocysticercosis.

METHODS

Twelve patients with a diagnosis of active brain parenchymal neurocysticercosis treated with albendazole for 8 days (15 mg kg(-1) day(-1)) were investigated. On day 8, serial blood samples were collected during the dose interval (0-12 h) and one CSF sample was taken from each patient by lumbar puncture at different time points up to 12 h after the last albendazole dose. Albendazole metabolites were determined in CSF and plasma samples by h.p.l.c. using a Chiralpak AD column and fluorescence detection. Population curves for CSF albendazole metabolite concentration vs time were constructed.

RESULTS

The mean plasma/CSF ratios were 2.6 (95% CI: 1.9, 3.3) for (+)-ASOX and 2.7 (95% CI: 1.8, 3.7) for (-)-ASOX, with the two-tailed P value of 0.9873 being non-significant. These data indicate that the transport of ASOX through the blood-brain barrier is not enantioselective, but rather depends on passive diffusion. The present results suggest the accumulation of the (+)-ASOX metabolite in the CSF of patients with neurocysticercosis. The CSF AUC(+)/AUC(-) ratio was 3.4 for patients receiving albendazole every 12 h. The elimination half-life of both ASOX enantiomers in CSF was 2.5 h. ASOX was the predominant metabolite in the CSF compared with ASON; the CSF AUC(ASOX)/AUC(ASON) ratio was approximately 20 and the elimination half-life of ASON in CSF was 2.6 h.

CONCLUSIONS

We have demonstrated accumulation of the (+)-ASOX metabolite in CSF, which was about three times greater than the (-) antipode. ASOX concentrations were approximately 20 times higher than those observed for the ASON metabolite.

Hydatid lung disease (echinococcosis/hydatidosis)

Two Echinococcus species may exhibit medical relevance as causative agents of pulmonary forms of echinococcosis. Most importantly, infections with Echinococcus granulosus result in "cystic hydatid disease" or "cystic echinococcosis," which affects the lungs in a considerable ratio of cases. Echinococcus multilocularis, which causes "alveolar echinococcosis," affects the lungs relatively rarely and then usually upon metastasizing from primary hepatic lesions. Cystic echinococcus and alveolar echinococcus differ pathologically and clinically so greatly that they are considered separately in this article, although alveolar echinococcus is covered minimally because of its minor importance regarding lung infections.

Enantioselective kinetic disposition of albendazole sulfoxide in patients with neurocysticercosis

The enantioselectivity of the kinetic disposition of albendazole sulfoxide (ASOX) was investigated in 18 patients with neurocysticercosis treated with a multiple dose regimen of albendazole for 8 days (5 mg/kg every 8 h). Serial blood samples were collected on the eighth day of treatment during the last dose interval, with prorogation up to 12 h. Albendazole sulfone (ASON) and enantiomers of ASOX were analyzed in plasma samples by HPLC using a Chiralpak AD column and detection by fluorescence. The pharmacokinetic parameters showing statistically significant differences between the (+) ASOX and (-) ASOX enantiomers are presented as respective means (95% CI) as follows: maximum plasma concentration, Cmax = 301.6 (179.7-423.5) vs 54.9 (21.9-87.9) ng.ml-1; elimination half-life, t1/2 = 5.2 (4.1-6.3) vs 3.3 (2.8-3.8) h, area under the plasma concentration-time curve, AUCss0-8 = 1719.2 (978.6-2459.8) vs 261.4 (102.9-419.8) ng.h.ml-1 and apparent clearance, Cl/fm = 5.8 (3.8-7.8) vs 54.0 (35.2-72.7) l.h-1.kg-1. The mean value of 9.2 (7.6-10.9) for the AUC0-8(+)-ASOX/AUC0-8(-)-ASOX ratio demonstrated plasma accumulation of the (+) enantiomer. Sulfone formation capacity, expressed by the AUCss0-8 ratio ASON/ASOX + ASON, was 8.0 (7.0-8.9). The present data indicate enantioselectivity in the kinetic disposition of ASOX in patients with neurocysticercosis.

Therapy for neurocysticercosis: pharmacokinetic interaction of albendazole sulfoxide with dexamethasone

Albendazole is considered the drug of choice for neurocysticercosis. It is frequently used in combination with dexamethasone to prevent the acute inflammatory reaction due to cysticercal death. It has been reported that dexamethasone increases the plasma level of albendazole sulfoxide, the active metabolite of albendazole. The pharmacokinetic interaction of albendazole sulfoxide with dexamethasone, associated or not with cimetidine, was investigated in 24 patients with active intraparenchymal brain cysticercosis. Eight of these patients received albendazole alone, eight received it in combination with dexamethasone, and eight received it in combination with both dexamethasone and cimetidine. The pharmacokinetic parameters maximum plasma concentration, time to maximum plasma concentration, absorption half-life, and absorption rate constant did not differ between groups, suggesting that the formation of albendazole sulfoxide was not altered by the administration of dexamethasone, combined or not with cimetidine. There were significant differences, however, in the parameters plasma concentration-time curve, oral clearance, elimination half-life, and elimination rate constant, suggesting that dexamethasone, combined or not with cimetidine, decreases the rate of elimination of albendazole sulfoxide.

Cestodes. Echinococcus

This article deals with cystic echinococcosis (CE) and alveolar echinococcosis in humans caused by the cestode parasites Echinococcus granulosus and Echinococcus multilocularis. The life cycles of these parasites and their epidemiologic aspects are briefly discussed, and a detailed review is presented on clinical aspects of the diseases, including diagnosis and therapy. Considerable progress has been made in chemotherapy but the results are not yet satisfactory. A new alternative for treatment of CE is puncture of cysts, aspiration of fluid, injection of ethanol, and reaspiration of fluid (PAIR).

Development of an injectable formulation of albendazole and in vivo evaluation of its efficacy against Echinococcus multilocularis metacestode

The loading of poly (D, L-lactide) nanoparticles with ABZ has led us to evaluate the potential of this new colloidal drug delivery system against E. multilocularis, using a murine model of hepatic alveolar echinococcosis. ABZ-loaded nanoparticles had a monodisperse size distribution between 100 and 150 nm. The efficiency of drug loading to nanoparticles was over 97%. In vitro, at an ABZ concentration of 1.0 microgram ml-1, the formulation had no toxicity for peritoneal macrophages harvested from uninfected mice. In vivo, the ABZ-loaded nanoparticles exhibited no signs of toxicity at any of the doses tested. Intravenous injections of 6 mg kg-1 of bound ABZ to infected mice had an equivalent antiparasitic effect on the metacestode growth to that of a treatment with 1500 mg kg-1 of orally administered free ABZ. The parasite hepatic superficial size as well as the peritoneal metastatic burden was significantly reduced by these 2 courses of treatment, as compared to those of untreated mice. Our results should encourage further study in order to explain the absence of dose-dependent efficacy of ABZ-loaded nanoparticles demonstrated in the present study.