Combined flubendazole-nitazoxanide treatment of cystic echinococcosis: Pharmacokinetic and efficacy assessment in mice

Optimizing adjuvant inhaled chemotherapy: Synergistic enhancement in paclitaxel cytotoxicity by flubendazole nanocrystals in a cycle model approach

Lung cancer is the leading cause of cancer-related death. In addition to new innovative approaches, practical strategies that improve the efficacy of already available drugs are urgently needed. In this study, an inhalable dry powder formulation is used to repurpose flubendazole, a poorly soluble anthelmintic drug with potential against a variety of cancer lineages. Flubendazole nanocrystals were obtained through nanoprecipitation, and dry powder was produced by spray drying. Through fractional factorial design, the spray drying parameters were optimized and the impact of formulation on aerolization properties was clarified. The loading limitations were clarified through response surface methodology, and a 15% flubendazole loading was feasible through the addition of 20% L-leucine, leading to a flubendazole particle size of 388.6 nm, median mass aerodynamic diameter of 2.9 μm, 50.3% FPF, emitted dose of 83.2% and triple the initial solubility. Although the cytotoxicity of this formulation in A549 cells was limited, the formulation showed a synergistic effect when associated with paclitaxel, leading to a surprising 1000-fold reduction in the IC50. Compared to 3 cycles of paclitaxel alone, a 3-cycle model combined treatment increased the threshold of cytotoxicity by 25% for the same dose. Our study suggests, for the first time, that orally inhaled flubendazole nanocrystals show high potential as adjuvants to increase cytotoxic agents' potency and reduce adverse effects.

Status and prospect of novel treatment options toward alveolar and cystic echinococcosis

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are the two most important global parasitic infectious diseases caused by species of Echinococcus granulosus and E. multilocularis, respectively. Although numerous trials have been performed in search of novel therapeutic options to curb the neglected zoonosis, no other nonsurgical options are currently available to replace the licensed anti echinococcal drugs albendazole (ABZ) and mebendazole (MBZ). A safer and more effective treatment plan for echinococcosis is therefore urgently needed to compensate for this therapeutic shortfall. Here, we present a review of the literature for state-of-the-art valuable anti-parasitic compounds and novel strategies that have proved effective against CE and AE, which includes details about the pharmaceutical type, practical approach, experimental plan, model application and protoscolecidal effects in vivo and in vitro. The content includes the current application of traditional clinical chemicals, the preparation of new compounds with various drug loadings, repurposing findings, combined programs, the prospects for Chinese herbal medicines, non-drug administrations and the exploration of target inhibitors based on open-source information for parasitic genes. Next the conventional experimental projects and pharmacodynamic evaluation methods are systematically summarized and evaluated. The demands to optimize the construction of the echinococcosis model and improve the dynamic monitoring method in vivo are also discussed given the shortcomings of in vivo models and monitoring methods.

The combination of carvacrol and albendazole enhanced the efficacy of monotherapy in experimental alveolar echinococcosis

Alveolar echinococcosis is a helminthic zoonosis caused by the larval stage of Echinococcus multilocularis. When surgical resection of the parasite is not feasible, pharmacological treatment with albendazole is the only option. Due to the difficulties in achieving the success of treatment, it is necessary to find new drugs to improve the treatment of this disease. In the present work, the efficacy of carvacrol alone or combined with albendazole was evaluated against E. multilocularis metacestodes. The association of carvacrol with albendazole produced a greater in vitro effect than the compounds incubated separately. The most effective treatment was the combination of 10 μg/ml of carvacrol and 1 μg/ml of albendazole. In the clinical efficacy study, treatment of infected mice with carvacrol (40 mg/kg) and albendazole (25 mg/kg) reduced the weight of metacestodes by 29 % and 50 %, respectively; while the combination of drugs had an efficacy of 83 %. These results coincided with the tissue damage observed at the ultrastructural level. In conclusion, carvacrol and albendazole combination enhanced the efficacy of monotherapy. This strategy would allow to improve the efficacy of the treatment without increasing the doses of albendazole or lengthen the treatment period, reducing the occurrence of adverse effects.

Alterations in Taenia crassiceps cysticerci cytoskeleton induced by nitazoxanide and flubendazole

Cysticercosis is the presence of Taenia solium larval stage in tissues such as central nervous system, skin, muscles and eye globe. The current treatment is based on albendazole and praziquantel which already present resistance reports. Therefore, the search for alternative treatments is paramount. The aim of this study was to determine the effect of flubendazole and nitazoxanide on cytoskeleton proteins from Taenia crassiceps cysticerci, an experimental model for cysticercosis. Cysticerci were cultured in RPMI supplemented medium containing nitazoxanide and/or flubendazole. 24 h after the exposure the cysticerci were processed for scanning and transmission electron microscopy and for protein analysis of the cytoskeleton. The proteins were detected through 1D electrophoresis and identified through Western Blot. Nitazoxanide exposure increased tubulin and actin quantifications in T. crassiceps cysticerci. While flubendazole alone and the drugs combinations induced an increase in α-tubulin and actin and decreased β-tubulin quantifications in the parasite. Morphological changes such as swelling and rupture of vesicle, stiff membrane, decrease in movements were observed when the cysticerci were incubated with the different compounds. In conclusion the drugs induced significative impact in the parasite`s cytoskeleton and may be considered as alternative treatments for cysticercosis.

In vitro effects of tropisetron and granisetron against Echinococcus granulosus (s.s.) protoscoleces by involvement of calcineurin and calmodulin

Background

Cystic echinococcosis (CE) is a disease caused by the larval stage of Echinococcus granulosus sensu lato  (s.l.). The treatment of CE mainly relies on the use of benzimidazoles, which can commonly cause adverse side effects. Therefore, more efficient treatment options are needed. Drug repurposing is a useful approach for advancing drug development. We have evaluated the in vitro protoscolicidal effects of tropisetron and granisetron in E. granulosus sensu stricto (s.s.) and assessed the expression of the calcineurin (CaN) and calmodulin (CaM) genes, both of which have been linked to cellular signaling activities and thus are potentially promising targets for the development of drugs.

Methods

Protoscoleces (PSC) of E. granulosus (s.s.) (genotype G1) obtained from sheep hepatic hydatid cysts were exposed to tropisetron and granisetron at concentrations of 50, 150 and 250 µM for various periods of time up to 10 days. Cyclosporine A (CsA) and albendazole sulfoxide were used for comparison. Changes in the morphology of PSC were investigated by light microscopy and scanning electron microscopy. Gene expression was assessed using real-time PCR at the mRNA level for E. granulosus calcineurin subunit A (Eg-CaN-A), calcineurin subunit B (Eg-CaN-B) and calmodulin (Eg-CaM) after a 24-h exposure at 50 and 250 µM, respectively.

Results

At 150 and 250 µM, tropisetron had the highest protoscolicidal effect, whereas CsA was most effective at 50 µM. Granisetron, however, was less effective than tropisetron at all three concentrations. Examination of morphological alterations revealed that the rate at which PSC were killed increased with increasing rate of PSC evagination, as observed in PSC exposed to tropisetron. Gene expression analysis revealed that tropisetron at 50 μM significantly upregulated Eg-CaN-B and Eg-CaM expression while at 250 μM it significantly downregulated both Eg-CaN-B and Eg-CaM expressions; in comparison, granisetron decreased the expression of all three genes at both concentrations.

Conclusions

Tropisetron exhibited a higher efficacy than granisetron against E. granulosus (s.s.) PSC, which is probably due to the different mechanisms of action of the two drugs. The concentration-dependent effect of tropisetron on calcineurin gene expression might reflect its dual functions, which should stimulate future research into its mechanism of action and evaluation of its potential therapeutical effect in the treatment of CE.

Graphic Abstract

Efficacy of novel albendazole salt formulations against secondary cystic echinococcosis in experimentally infected mice

In this study, we evaluated the efficacy, expressed as a mean weight decrease of the whole echinococcal cyst mass, of novel benzimidazole salt formulations in a murine Echinococcus granulosus infection model. BALB/c mice were intraperitoneally infected with protoscoleces of E. granulosus (genotype G1). At 9 months post-infection, treatment with albendazole (ABZ), ricobendazole (RBZ) salt formulations, and RBZ enantiomer salts (R)-(+)-RBZ-Na and (S)-(-)-RBZ-Na formulations were initiated. Drugs were orally applied by gavage at 10 mg kg-1 body weight per day during 30 days. Experimental treatments with benzimidazole sodium salts resulted in a significant reduction of the weight of cysts compared to conventional ABZ treatment, except for the (S)-(-)-RBZ-Na enantiomer formulation. Scanning electron microscopy and histological inspection revealed that treatments impacted not only the structural integrity of the parasite tissue in the germinal layer, but also induced alterations in the laminated layer. Overall, these results demonstrate the improved efficacy of benzimidazole salt formulations compared to conventional ABZ treatment in experimental murine cystic echinococcosis.

Subcutaneous Hydatid Cyst in Laboratory Mice: Is it a Suitable Method for Evaluating Therapeutic Agents against Hydatid Cyst?

Hydatid disease is an economic and public health concern in many countries. Currently, surgery is the main treatment option for hydatid disease. In the surgical treatment of hydatidosis, the use of scolicidal agents is very important due to inactivating live protoscoleces and preventing the recurrence of infection. Therefore, it is necessary to investigate newscolicidal agents and novel medications with higher safety and efficacy. In the previous in vitro studies, the scolicidal effects of the methanolic extracts and aromatic water of Zataria multiflora (Z. multiflora) have been demonstrated. Consequently, in this study, the impact of the nanoemulsion of Z. multiflora essential oil on subcutaneous hydatid cysts was compared with albendazole (ABZ). Fifty laboratory male mice were inoculated with 300 viable protoscoleces subcutaneously on the two sides of the abdomen. Following five months of infection, the remaining infected mice (n=42) were allocated into two treatment and one control (without treatment) groups containing fourteen animals each. Group A received ABZ at the dose of 50 mg/kg for 60 days, group B received the nanoemulsions of Z. multiflora at the dose of 50 mg/kg in drinking water for 60 days, and group C was considered as the control group. All the infected mice were euthanized and necropsied two months post-intervention. Afterwards, the cysts were cautiously collected and their number, size, and weight were compared between the mice of different groups. The mean number of hydatid cysts indicated that the nanoemulsion of Z. multiflora essence had a relative superiority to ABZ. On the other hand, the therapeutic effect of ABZ was higher than the nanoemulsion of Z. multiflora essential oil in terms of the mean weight and mean size of hydatid cysts. However, no significant difference was observed between the groups (P>0.5). Overall, the number, weight, and size of cysts were not significantly different between the groups in this investigation. The lack of satisfactory therapeutic results in this study might be due to the location of hydatid cysts in the subcutaneous space.

The combination of Cytokines and albendazole therapy for prophylaxis and treatment of experimental/hydatid cyst

Albendazole is appropriate chemotherapy for treatment and prophylaxis of cystic echinococcosis (CE). The recent studies show Cytokine therapy could be useful for chronic and progressive diseases, therefore, the use of cytokine in prophylaxis and treatment of hydatidosis could be considerable. The aim of this study is to evaluate the efficacy of interleukin-12 + interferon-gamma, in combination with albendazole for prophylaxis and treatment of CE in Balb/c mice. Albendazole and cytokines were administrated for prophylaxis and treatment in CE. The efficacy of this agents were determined by measuring of size, weight, number of cysts, histology and lymphocyte response. Lymphocyte stimulation index and production of interleukin-12 and interferon-gamma were measured by MTT assay and ELISA respectively. Combination of albendazole and cytokines was very effective for prophylaxis and treatment in experimental CE.

Progress in the pharmacological treatment of human cystic and alveolar echinococcosis: Compounds and therapeutic targets

Human cystic and alveolar echinococcosis are helmintic zoonotic diseases caused by infections with the larval stages of the cestode parasites Echinococcus granulosus and E. multilocularis, respectively. Both diseases are progressive and chronic, and often fatal if left unattended for E. multilocularis. As a treatment approach, chemotherapy against these orphan and neglected diseases has been available for more than 40 years. However, drug options were limited to the benzimidazoles albendazole and mebendazole, the only chemical compounds currently licensed for treatment in humans. To compensate this therapeutic shortfall, new treatment alternatives are urgently needed, including the identification, development, and assessment of novel compound classes and drug targets. Here is presented a thorough overview of the range of compounds that have been tested against E. granulosus and E. multilocularis in recent years, including in vitro and in vivo data on their mode of action, dosage, administration regimen, therapeutic outcomes, and associated clinical symptoms. Drugs covered included albendazole, mebendazole, and other members of the benzimidazole family and their derivatives, including improved formulations and combined therapies with other biocidal agents. Chemically synthetized molecules previously known to be effective against other infectious and non-infectious conditions such as anti-virals, antibiotics, anti-parasites, anti-mycotics, and anti-neoplastics are addressed. In view of their increasing relevance, natural occurring compounds derived from plant and fungal extracts are also discussed. Special attention has been paid to the recent application of genomic science on drug discovery and clinical medicine, particularly through the identification of small inhibitor molecules tackling key metabolic enzymes or signalling pathways.

Human cystic and alveolar echinococcosis (CE and AE), caused by the larval stages of the helminths Echinococcus granulosus and E. multilocularis, respectively, are progressive and chronic diseases affecting more than 1 million people worldwide. Both are considered orphan and neglected diseases by the World Health Organization. As a treatment approach, chemotherapy is limited to the use of benzimidazoles, drugs that stop parasite growth but do not kill the parasite. To compensate this therapeutic shortfall, new treatment alternatives are urgently needed. Here, we present the state-of-the-art regarding the alternative compounds and new formulations of benzimidazoles assayed against these diseases until now. Some of these new and modified compounds, either alone or in combination, could represent a step forward in the treatment of CE and AE. Unfortunately, few compounds have reached clinical trials stage in humans and, when assayed, the design of these studies has not allowed evidence-based conclusions. Thus, there is still an urgent need for defining new compounds or improved formulations of those already assayed, and also for a careful design of clinical protocols that could lead to the draw of a broad international consensus on the use of a defined drug, or a combination of drugs, for the effective treatment of CE and AE.

Inhibition of vaccinia virus replication by nitazoxanide

Nitazoxanide (NTZ) is an FDA-approved anti-protozoal drug that inhibits several bacteria and viruses as well. However, its effect on poxviruses is unknown. Therefore, we investigated the impact of NTZ on vaccinia virus (VACV). We found that NTZ inhibits VACV production with an EC₅₀ of ~2 μM, a potency comparable to that reported for several other viruses. The inhibitory block occurs early during the viral life cycle, prior to viral DNA replication. The mechanism of viral inhibition is likely not due to activation of intracellular innate immune pathways, such as protein kinase R (PKR) or interferon signaling, contrary to what has been suggested to mediate the effects of NTZ against some other viruses. Rather, our finding that addition of exogenous palmitate partially rescues VACV production from the inhibitory effect of NTZ suggests that NTZ impedes adaptations in cellular metabolism that are needed for efficient completion of the VACV replication cycle.

Experimental cystic echinococcosis therapy: In vitro and in vivo combined 5-fluorouracil/albendazole treatment

Human cystic echinococcosis is a zoonosis caused by the larval stage of the tapeworm Echinococcus granulosus sensu lato (s. l.). Although benzimidazole compounds such as albendazole (ABZ) and mebendazole have been the cornerstone of chemotherapy for the disease, there is often no complete recovery after treatment. Hence, new strategies are required to improve treatment of human cystic echinococcosis. The goals of the current study were as follows: (i) to evaluate the in vitro efficacy of the 5-fluorouracil (5-FU) and ABZ combination against E. granulosus s. l. protoscoleces and cysts, (ii) to compare the clinical efficacy of 5-FU alone or in combination with ABZ in infected mice. The combination of 5-FU+ABZ had a stronger in vitro effect against larval stage than that did both drugs alone. Even at the lowest concentration of 5-FU+ABZ combination (1μg/ml), the reduction of the viability of protoscoleces and cysts was greater than that observed with drugs alone at 10μg/ml. The results were confirmed at the ultrastructural level by scanning electron microscopy. These data helped to justify the in vivo investigations assessing the therapeutic potential of the combination of 5-FU and ABZ suspension in CF-1 mice infected with E. granulosus sensu stricto (s. s.) metacestodes. Treatment with 5-FU (10mg/kg) or 5-FU (10mg/kg) + ABZ suspension (5mg/kg) reduced the weight of cysts recovered from mice compared with control groups. Interestingly, the effect of 5-FU given weekly for 5 consecutive weeks was comparable to that observed with ABZ suspension under a daily schedule during 30days. Co-administration of 5-FU with ABZ did not enhance the in vivo efficacy of drugs alone calculated in relation to cysts weights. However, the combination provoked greater ultrastructural alterations compared to the monotherapy. In conclusion, we demonstrated the efficacy of 5-FU either alone or co-administrated with ABZ against murine experimental cystic echinococcosis. Since 5-FU treatments did not cause toxic effect in mice, further in vivo studies will be performed by adjusting the dosage and the frequency of treatments.

In vivo evaluation of the efficacy of combined albedazole-IFN-α treatment for cystic echinococcosis in mice

Cystic echinococcosis (CE) is a serious helminthic zoonosis caused by Echinococcus granulosus metacestode worldwide. The current chemotherapy of CE is mainly based on albendazole (ABZ). However, more than 20% CE cases failed to such chemotherapy. Thus, novel and more efficient treatment options are urgently needed. This study was to evaluate the in vivo efficacy of combined ABZ-interferon (IFN)-α treatment for CE in mice. After 5 months of secondary infection with protoscoleces, mice were randomly allocated into four groups: ABZ-treated group, IFN-α-treated group, ABZ+IFN-α group, and untreated control group. Drugs in diverse treated groups were respectively administered for 2 months. Mice were then euthanized and associated indications were investigated to evaluate the therapeutic efficacy. ABZ+IFN-α induced a significant reduction of the number, size, as well as weight of cysts, compared with that in the ABZ (p < 0.05) or untreated group (p < 0.01), respectively. This effect was associated with ultrastructural modification of the cyst in the ABZ+IFN-α group. Interestingly, significant decrease of IL (interleukin)-10 in serum and in vitro production by spleen cells with ABZ+IFN-α treatment was observed in comparison with untreated control (p < 0.01). Serum IgE, IgG, and subsets were respectively decreased in ABZ+IFN-α treatment, compared with that in the control group (p < 0.01). In conclusion, our findings demonstrated that combination of ABZ with IFN-α may contribute to an efficient therapeutic regimen of human and animal CE.

Effect of nitazoxanide on albendazole pharmacokinetics in cerebrospinal fluid and plasma in rats

Background: Although albendazole is the drug-of-choice for the treatment of neurocysticercosis, its efficacy is limited due to its low bioavailability. An alternative for optimizing pharmacological treatment is through drug combinations. In vitro studies have shown that nitazoxanide and tizoxanide (the active metabolite of nitazoxanide) exhibit cysticidal activity and that the combination of tizoxanide with albendazole sulfoxide (the active metabolite of albendazole) produced an additive effect. Objectives: (1) To assess the concentration profile of tizoxanide in plasma and in cerebrospinal fluid; and (2) to evaluate the influence of nitazoxanide on the pharmacokinetics of albendazole in plasma and in cerebrospinal fluid. Methods: Two different studies were conducted. In study 1, 10 male Sprague-Dawley rats received a single oral dose of 7.5 mg/kg of nitazoxanide and serial blood and cerebrospinal fluid samples were collected over a period of 4 h. In study 2, 38 healthy male Sprague-Dawley rats were randomly divided into two groups: one of these received a single dose of albendazole (15 mg/kg) and, in the other group, albendazole (15 mg/kg) was co-administered with nitazoxanide (7.5 mg/kg). Plasma and cerebrospinal fluid samples were collected from 0 to 16 h after administration. Albendazole sulfoxide and tizoxanide levels were assayed by using HPLC or LC/MS techniques. Results: In study 1, tizoxanide reached a maximum plasma concentration of 244.42 ± 31.98 ng/mL at 0.25 h; however, in cerebrospinal fluid, this could be detected only at 0.5 h, and levels were below the quantification limit (10 ng/mL). These data indicate low permeation of tizoxanide into the blood brain barrier. In study 2, Cmax, the area under the curve, and the mean residence time of albendazole sulfoxide in plasma and cerebrospinal fluid were not affected by co-administration with nitazoxanide. Conclusion: The results of the present study indicate that in rats at the applied doses, tizoxanide does not permeate into the cerebrospinal fluid. Furthermore, nitazoxanide does not appear to alter significantly the pharmacokinetics of albendazole in plasma or in cerebrospinal fluid.