Effect of Fascioliasis on the pharmacokinetic parameters of triclabendazole in human subjects

Fosfatriclaben, a prodrug of triclabendazole: Preparation, stability, and fasciolicidal activity of three new intramuscular formulations

In this study, we present the preparation, stability, and in vivo fasciolicidal activity of three new intramuscular formulations in sheep of a prodrug based on triclabendazole, named fosfatriclaben. The new formulations were ready-to-use aqueous solutions with volumes recommended for intramuscular administration in sheep. The use of poloxamers (P-407 and P-188) and polysorbates (PS-20 and PS-80) in the new formulations improved the aqueous solubility of fosfatriclaben by 8-fold at pH 7.4. High-performance liquid chromatography with UV detection was used to evaluate the stability of fosfatriclaben in the three formulations. High recovery (> 90%) of fosfatriclaben was found for all formulations after exposure at 57 ± 2 °C for 50 h. The three intramuscular formulations showed high fasciolicidal activity at a dose of 6 mg/kg, which was equivalent to the triclabendazole content. The fasciolicidal activity of fosfatriclaben was similar to commercial oral (Fasimec®) and intramuscular (Endovet®) triclabendazole formulations at a dose of 12 mg/kg. In the in vivo experiments, all formulations administered intramuscularly reduced egg excretion by 100%, and formulations F1, F2, and F3 presented fasciolicidal activities of 100%, 100%, and 99.6%, respectively.

Repositioning of the Anthelmintic Drugs Bithionol and Triclabendazole as Transthyretin Amyloidogenesis Inhibitors

Transthyretin (TTR) is a causative protein of TTR amyloidosis (ATTR amyloidosis), a general term for diseases characterized by deposition of TTR amyloid fibrils in specific organs. ATTR amyloidosis can be ameliorated by stabilization of the TTR tetramer through the binding of small molecules. Here, we show that the clinical anthelmintic drugs bithionol (42) and triclabendazole (43) potently inhibit aggregation of the amyloidogenic variant V30M-TTR. A competitive binding assay using a fluorescence probe showed that the binding affinity of 42 with V30M-TTR was significantly higher than that of the first-in-class drug tafamidis (1), and the binding affinity of 43 was similar to that of 1. The crystallographic and thermodynamic analysis revealed that 42 efficiently occupied the halogen-binding grooves of TTR, resulting in the favorable binding entropy. Multifaceted in vitro studies of anthelmintic drugs have the potential to reposition these drugs as ATTR amyloidosis inhibitors.

Repurposing of the Fasciolicide Triclabendazole to Treat Infections Caused by Staphylococcus spp. and Vancomycin-Resistant Enterococci

One approach to combat the increasing incidence of multidrug-resistant (MDR) bacterial pathogens involves repurposing existing compounds with known safety and development pathways as new antibacterial classes with potentially novel mechanisms of action. Here, triclabendazole (TCBZ), a drug originally developed to treat Fasciola hepatica (liver fluke) in sheep and cattle, and later in humans, was evaluated as an antibacterial alone or in combination with sub-inhibitory concentrations of polymyxin B (PMB) against clinical isolates and reference strains of key Gram-positive and Gram-negative bacteria. We show for the first time that in vitro, TCBZ selectively kills methicillin-sensitive and methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius at a minimum inhibitory concentration (MIC) range of 2–4 µg/mL, and vancomycin-resistant enterococci at a MIC range of 4–8 µg/mL. TCBZ also inhibited key Gram-negative bacteria in the presence of sub-inhibitory concentrations of PMB, returning MIC₉₀ values of 1 µg/mL for Escherichia coli, 8 µg/mL for Klebsiella pneumoniae, 2 µg/mL for Acinetobacter baumannii and 4 µg/mL for Pseudomonasaeruginosa. Interestingly, TCBZ was found to be bacteriostatic against intracellular S. aureus but bactericidal against intracellular S. pseudintermedius. Additionally, TCBZ’s favourable pharmacokinetic (PK) and pharmacodynamic (PD) profile was further explored by in vivo safety and efficacy studies using a bioluminescent mouse model of S. aureus sepsis. We show that repeated four-hourly oral treatment of mice with 50 mg/kg TCBZ after systemic S. aureus challenge resulted in a significant reduction in S. aureus populations in the blood to 18 h post-infection (compared to untreated mice) but did not clear the bacterial infection from the bloodstream, consistent with in vivo bacteriostatic activity. These results indicate that additional pharmaceutical development of TCBZ may enhance its PK/PD, allowing it to be an appropriate candidate for the treatment of serious MDR bacterial pathogens.

Triclabendazole for the treatment of human fascioliasis and the threat of treatment failures

INTRODUCTION

The only drug effective against the infection caused by Fasciola hepatica or F. gigantica is triclabendazole (TCBZ), recommended by the WHO and recently approved by the FDA. Here, we describe the evolution of TCBZ regimens and the emergence of TCBZ failure to Fasciola infection.

AREAS COVERED

The present review focuses on the evidence of TCBZ for the treatment of fascioliasis. For acute fascioliasis, there is a lack of studies to measure the presence of eggs of Fasciola in stool samples on the follow-up after initial TCBZ treatment. For chronic fascioliasis, WHO recommends a single oral dose of TCBZ 10 mg/kg whereas CDC recommends two doses of TCBZ 10 mg/kg 12 h apart. Incremental number of treatment failures have been documented worldwide. There are currently no therapeutic alternatives for the treatment of fascioliasis in humans.

EXPERT OPINION

Most cases of human fascioliasis are successfully treated with TCBZ, but some continue excreting eggs in the stools despite 1-2 standard of care regimens of TCBZ. A precise regimen is unclear for those patients who fail the initial treatment with TCBZ. Further clinical trials are needed to address the possible TCBZ emerging resistance.

Triclabendazole in the treatment of human fascioliasis: a review

Fascioliasis occurs on all inhabited continents. It is caused by Fasciola hepatica and Fasciola gigantica, trematode parasites with complex life cycles, and primarily affects domestic livestock. Humans become infected after ingestion of contaminated food (typically wild aquatic vegetables) or water. Fascioliasis may be difficult to diagnose as many symptoms are non-specific (e.g. fever, abdominal pain and anorexia). Treatment options are limited, with older effective therapies such as emetine and bithionol no longer used due to safety issues and unavailability, and most common anthelminthics having poor efficacy. Clinical trials conducted over a 25-year period, together with numerous case reports, demonstrated that triclabendazole has high efficacy in the treatment of human fascioliasis in adults and children and in all stages and forms of infection. Triclabendazole was approved for human use in Egypt in 1997 and in France in 2002 and a donation program for the treatment of fascioliasis in endemic countries was subsequently established by the manufacturer and administered by the World Health Organization. Here the published data on triclabendazole in the treatment of human fascioliasis are reviewed, with a focus on more recent data, in light of the 2019 US Food and Drug Administration approval of the drug for use in human infections.

Proniosomal Microcarriers: Impact of Constituents on the Physicochemical Properties of Proniosomes as a New Approach to Enhance Inhalation Efficiency of Dry Powder Inhalers

Proniosomes are free-flowing systems with coating carriers, which developed as a method for improving the drug flow and pulmonary delivery. Extensive research on proniosomes was done to enhance the dry powder inhalers (DPI)'s inhalation performance. This research aimed at studying the impact of lactose-mannitol mixture additives on the proniosome's physicochemical properties as a method for improving the inhalation efficiency of DPI. Vismodegib has been employed as a compound model. Box-Behnken design has been employed to prepare different proniosomes formulae by incorporating various (A) span 60 concentrations, (B) lactose concentrations and (C) mannitol: total carrier mixture. The measured responses were vesicle size (R₁), %release (R₂), Carr's index (R₃) and %recovery (R₄). The results displayed that R₁ and R₄ were significantly antagonistic to C and significantly synergistic to both A and B while R₂ and R₃ were significantly synergistic to C and significantly antagonistic to both A and B. The optimal formula was selected for its aerodynamic behaviour, cytotoxic activity and bioavailability assessment. The optimal formula resulted in better Vismodegib lung deposition, cytotoxic activity and relative bioavailability. This novel formula could be a promising carrier for sustained delivery of drugs via the pulmonary route.

Systemic and Target-Site Pharmacokinetics of Antiparasitic Agents

About one-sixth of the world's population is affected by a neglected tropical disease as defined by the World Health Organization and Center for Disease Control. Parasitic diseases comprise most of the neglected tropical disease list and they are causing enormous amounts of disability, morbidity, mortality, and healthcare costs worldwide. The burden of disease of the top five parasitic diseases has been estimated to amount to a total 23 million disability-adjusted life-years. Despite the massive health and economic impact, most drugs currently used for the treatment of parasitic diseases have been developed decades ago and insufficient novel drugs are being developed. The current review provides a compilation of the systemic and target-site pharmacokinetics of established antiparasitic drugs. Knowledge of the pharmacokinetic profile of drugs allows for the examination and possibly optimization of existing dosing schemes. Many symptoms of parasitic diseases are caused by parasites residing in different host tissues. Penetration of the antiparasitic drug into these tissues, the target site of infection, is a prerequisite for a successful treatment of the disease. Therefore, for the examination and improvement of established dosing regimens, not only the plasma but also the tissue pharmacokinetics of the drug have to be considered. For the current paper, almost 7000 scientific articles were identified and screened from which 429 were reviewed in detail and 100 were included in this paper. Systemic pharmacokinetics are available for most antiparasitic drugs but in many cases, not for all the relevant patient populations and only for single- or multiple-dose administration. Systemic pharmacokinetic data in patients with organ impairment and target-site pharmacokinetic data for relevant tissues and body fluids are mostly lacking. To improve the treatment of patients with parasitic diseases, research in these areas is urgently needed.

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.

Efficacy and tolerability of two single-day regimens of triclabendazole for fascioliasis in Peruvian children

INTRODUCTION

The therapeutic scheme of triclabendazole (TCBZ), the recommended anthelmintic against Fasciola hepatica , involves 10mg/kg of body weight administered in a single dose; however, clinical trials in children are scarce. We evaluated the efficacy and tolerability of 2 schemes of TCBZ.

METHODS

Eighty-four Peruvian children with F. hepatica eggs in their stools were allocated into 2 groups: 44 received 2 dosages of 7.5mg/kg each with a 12-h interval (Group I), and 40 received a single 10-mg/kg dose (Group II). Evaluation of efficacy was based on the presence of eggs in stools, and tolerability was based on the presence of symptoms and signs post-treatment.

RESULTS

A parasitological cure was obtained in 100% of individuals from Group I and 95% of individuals from Group II. The most common adverse event was biliary colic.

CONCLUSIONS

The tested scheme was efficacious and tolerable, and it might be an optimal scheme in the region. To the best of our knowledge, this represents the largest series of children treated with TCBZ in a non-hospital setting.

Triclabendazole sulfoxide causes stage-dependent embryolethality in zebrafish and mouse in vitro

Background

Fascioliasis and paragonimiasis are widespread foodborne trematode diseases, affecting millions of people in more than 75 countries. The treatment of choice for these parasitic diseases is based on triclabendazole, a benzimidazole derivative which has been suggested as a promising drug to treat pregnant women and children. However, at the moment, this drug is not approved for human use in most countries. Its potential adverse effects on embryonic development have been scarcely studied, and it has not been assigned a pregnancy category by the FDA. Thus, to help in the process of risk-benefit decision making upon triclabendazole treatment during pregnancy, a better characterization of its risks during gestation is needed.

Methodology

The zebrafish embryo test, a preimplantation and a postimplantation rodent whole embryo culture were used to investigate the potential embryotoxicity/teratogenicity of triclabendazole and its first metabolite triclabendazole sulfoxide. Albendazole and albendazole sulfoxide were included as positive controls.

Principal Findings

Triclabendazole was between 10 and 250 times less potent than albendazole in inducing dysmorphogenic effects in zebrafish or postimplantation rodent embryos, respectively. However, during the preimplantation period, both compounds, triclabendazole and triclabendazole sulfoxide, induced a dose-dependent embryolethal effect after only 24 h of exposure in rodent embryos and zebrafish (lowest observed adverse effect concentrations = 10 μM).

Conclusions/Significance

In humans, after ingestion of the recommended doses of triclabendazole to treat fascioliasis and paragonimiasis (10 mg/kg), the main compound found in plasma is triclabendazole sulfoxide (maximum concentration 38.6 μM), while triclabendazole concentrations are approximately 30 times lower (1.16 μM). From our results it can be concluded that triclabendazole, at concentrations of the same order of magnitude as the clinically relevant ones, does not entail teratogenic potential in vitro during the organogenesis period, but its first metabolite triclabendazole sulfoxide has a high embryotoxic capacity in vitro during the preimplantation stage.

The anthelmintic triclabendazole and its metabolites inhibit the membrane transporter ABCG2/BCRP

ABCG2/BCRP is an ATP-binding cassette transporter that extrudes compounds from cells in the intestine, liver, kidney, and other organs, such as the mammary gland, affecting pharmacokinetics and milk secretion of antibiotics, anticancer drugs, and other compounds and mediating drug-drug interactions. In addition, ABCG2 expression in cancer cells may directly cause resistance by active efflux of anticancer drugs. The development of ABCG2 modulators is critical in order to improve drug pharmacokinetic properties, reduce milk secretion of xenotoxins, and/or increase the effective intracellular concentrations of substrates. Our purpose was to determine whether the anthelmintic triclabendazole (TCBZ) and its main plasma metabolites triclabendazole sulfoxide (TCBZSO) and triclabendazole sulfone (TCBZSO(2)) inhibit ABCG2 activity. ATPase assays using human ABCG2-enriched membranes demonstrated a clear ABCG2 inhibition exerted by these compounds. Mitoxantrone accumulation assays using murine Abcg2- and human ABCG2-transduced MDCK-II cells confirmed that TCBZSO and TCBZSO(2) are ABCG2 inhibitors, reaching inhibitory potencies between 40 and 55% for a concentration range from 5 to 25 μM. Transepithelial transport assays of ABCG2 substrates in the presence of both TCBZ metabolites at 15 μM showed very efficient inhibition of the Abcg2/ABCG2-mediated transport of the antibacterial agents nitrofurantoin and danofloxacin. TCBZSO administration also inhibited nitrofurantoin Abcg2-mediated secretion into milk by more than 2-fold and increased plasma levels of the sulfonamide sulfasalazine by more than 1.5-fold in mice. These results support the potential role of TCBZSO and TCBZSO(2) as ABCG2 inhibitors to participate in drug interactions and modulate ABCG2-mediated pharmacokinetic processes.

Interaction of anthelmintic drugs with P-glycoprotein in recombinant LLC-PK1-mdr1a cells

Given the widespread use of formulations combining anthelmintics which are possible P-glycoprotein interfering agents, the understanding of drug interactions with efflux ABC transporters is of concern for improving anthelmintic control. We determined the ability of 14 anthelmintics from different classes to interact with abcb1a (mdr1a, P-glycoprotein, Pgp) by following the intracellular accumulation of rhodamine 123 (Rho 123), a fluorescent Pgp substrate, in LLC-PK1 cells overexpressing Pgp. The cytotoxicity of the compounds that are able to interfere with Pgp activity was evaluated in cells overexpressing Pgp and compared with parental cells using the MTS viability assay. Among all the anthelmintics used, ivermectin (IVM), triclabendazole (TCZ), triclabendazole sulfoxide (TCZ-SO), closantel (CLOS) and rafoxanide (RAF) increased the intracellular Rho 123 in Pgp overexpressing cells, while triclabendazole sulfone, albendazole, mebendazole, oxfendazole, thiabendazole, nitroxynil, levamisole, praziquantel and clorsulon failed to have any effect. The concentration needed to reach the maximal Rho 123 accumulation (E(max)) was obtained with 10 microM for IVM, 80 microM for CLOS, 40 microM for TCZ and TCZ-SO, and 80 microM for RAF. We showed that for these five drugs parental cell line was more sensitive to drug toxicity compared with Pgp recombinant cell line. Such in vitro approach constitutes a powerful tool to predict Pgp-drug interactions when formulations combining several anthelmintics are administered and may contribute to the required optimization of efficacy of anthelmintics.

Triclabendazole progress report, 2005–2009: an advancement of learning?

Triclabendazole (TCBZ) remains the drug of choice for treating infections of the liver fluke,Fasciola hepaticain livestock and has become the main drug used to treat human cases of the disease as well. Cases of resistance in livestock continue to be reported, suggesting that the problem is increasing. In order to address the problem, there is a need for better understanding of drug action. A ‘state-of-play’ review on different aspects of TCBZ activity was published by the present author in 2005. The main purpose of the current review is to assess what progress has been made in the past four years towards understanding the main aspects of drug activity, including drug pharmacokinetics and pharmacodynamics and an understanding of the mechanism(s) of resistance. Also, what advances have been made in identifying alternative compounds and using drug combinations to enhance TCBZ activity. Stemming from a number ofin vivostudies, it has become evident that fluke isolates of differing sensitivity to TCBZ differ in some of their biological parameters, and information on this interesting phenomenon will be presented. An update on the use of TCBZ for human fascioliasis is also given. The review will indicate what progress has been made, but will also highlight areas that remain inadequately understood and require greater research focus.

Update on hepatobiliary flukes: fascioliasis, opisthorchiasis and clonorchiasis

PURPOSE OF REVIEW

Hepatobiliary flukes--Fasciola, Opisthorchis, Clonorchis- are a major public health problem in east Asia, east Europe, Africa and Latin America. The present review focuses on current knowledge of clinical, diagnostic and treatment aspects caused by hepatobiliary flukes that can be applied to current protocols in endemic areas.

RECENT FINDINGS

Specific risk factors and geographic areas for these flukes have been heavily reported recently, with millions of people infected worldwide. Human cases in nonendemic areas, related to immigration and the international food trade (i.e. raw vegetables and fish), have also been reported. Diagnostic imaging changes include track-like lesions that are a characteristic feature of acute fascioliasis on computed tomography scanning of the liver. Newly available diagnostic serological tests may detect early infection and, therefore, help reduce severe clinical complications such as recurrent cholangitis, cholecystitis, hepatic tumours, cysts, calcification, cholelithiasis, pancreatitis, most importantly, cholangiocarcinoma related to Opisthorchis viverrini and possibly Clonorchis sinensis, and liver fibrosis associated with Fasciola hepatica infections. Highly effective antiparasitic treatment is available for all flukes.

SUMMARY

There is a better understanding of risk factors, clinical manifestations and complications, novel diagnosis tests and effective treatment, which together should help reduce the morbidity and mortality of these infections.