Failure of buparvaquone (Butalex) in the treatment of canine visceral leishmaniosis

Oral administration of buparvaquone nanostructured lipid carrier enables in vivo activity against Leishmania infantum

Leishmaniasis, a neglected tropical disease, is prevalent in 98 countries with the occurrence of 1.3 million new cases annually. The conventional therapy for visceral leishmaniasis requires hospitalization due to the severe adverse effects of the drugs, which are administered parenterally. Buparvaquone (BPQ) showed in vitro activity against leishmania parasites; nevertheless, it has failed in vivo tests due to its low aqueous solubility. Though, lipid nanoparticles can overcome this holdback. In this study we tested the hypothesis whether BPQ-NLC shows in vivo activity against L. infantum. Two optimized formulations were prepared (V1: 173.9 ± 1.6 nm, 0.5 mg of BPQ/mL; V2: 232.4 ± 1.6 nm, 1.3 mg of BPQ/mL), both showed increased solubility up to 73.00-fold, and dissolution up to 83.29%, while for the free drug it was only 2.89%. Cytotoxicity test showed their biocompatibility (CC50 >554.4 µM). Besides, the V1 dose of 0.3 mg/kg/day for 10 days reduced the parasite burden in 83.4% ±18.2% (p <0.05) in the liver. BPQ-NLC showed similar leishmanicidal activity compared to miltefosine. Therefore, BPQ-NLC is a promising addition to the limited therapeutic arsenal suitable for leishmaniasis oral administration treatment.

Orally Bioavailable and Effective Buparvaquone Lipid-Based Nanomedicines for Visceral Leishmaniasis

Nanoenabled lipid-based drug delivery systems offer a platform to overcome challenges encountered with current failed leads in the treatment of parasitic and infectious diseases. When prepared with FDA or EMA approved excipients, they can be readily translated without the need for further toxicological studies, while they remain affordable and amenable to scale-up. Buparvaquone (BPQ), a hydroxynapthoquinone with in vitro activity in the nanomolar range, failed to clinically translate as a viable treatment for visceral leishmaniasis due to its poor oral bioavailability limited by its poor aqueous solubility (BCS Class II drug). Here we describe a self-nanoemulsifying system (SNEDDS) with high loading and thermal stability up to 6 months in tropical conditions and the ability to enhance the solubilization capacity of BPQ in gastrointestinal media as demonstrated by flow-through cell and dynamic in vitro lipolysis studies. BPQ SNEDDS demonstrated an enhanced oral bioavailability compared to aqueous BPQ dispersions (probe-sonicated), resulting in an increased plasma AUC_0-24 by 55% that is 4-fold higher than any previous reported values for BPQ formulations. BPQ SNEDDS can be adsorbed on low molecular glycol chitosan polymers forming solid dispersions that when compressed into tablets allow the complete dissolution of BPQ in gastrointestinal media. BPQ SNEDDS and BPQ solid SNEDDS demonstrated potent in vitro efficacy in the nanomolar range (<37 nM) and were able to near completely inhibit parasite replication in the spleen while also demonstrating 48 ± 48 and 56 ± 23% inhibition of the parasite replication in the liver, respectively, compared to oral miltefosine after daily administration over 10 days. The proposed platform technology can be used to elicit a range of cost-effective and orally bioavailable noninvasive formulations for a range of antiparasitic and infectious disease drugs that are needed for closing the global health innovation gap.

Nanoliposomal Buparvaquone Immunomodulates Leishmania infantum-Infected Macrophages and Is Highly Effective in a Murine Model

Visceral leishmaniasis is a fatal parasitic neglected disease affecting 1.5 million people worldwide. Based on a drug repositioning approach, the aim of this work was to investigate the in vitro immunomodulatory potential of buparvaquone (BPQ) and to establish a safe regimen to evaluate the in vivo efficacy of BPQ entrapped by negatively charged nanoliposomes (BPQ-LP) in Leishmania infantum-infected hamsters. Small-angle X-ray scattering, dynamic light scattering, and the ζ-potential were applied in order to study the influence of BPQ on the liposome structure. Our data revealed that BPQ was located in the polar-apolar interface, snorkeling the polar region, and protected against aggregation inside the lipophilic region. The presence of BPQ also decreased the Z-average hydrodynamic diameter and increased the surface charge. Compared to intravenous and intramuscular administration, a subcutaneous route was a more effective route for BPQ-LP; at 0.4 mg/kg, BPQ-LP reduced infection in the spleen and liver by 98 and 96%, respectively. Treatment for 5 days resulted in limited efficacy, but 10 days of treatment resulted in an efficacy similar to that of a 15-day regimen. The nanoliposomal drug was highly effective, with a mean 50% effective dose of 0.25 mg/kg, reducing the parasite load in bone marrow by 80%, as detected using quantitative PCR analysis. In addition, flow cytometry studies showed that BPQ upregulated cytokines as tumor necrosis factor, monocyte chemoattractant protein 1, interleukin-10 (IL-10), and IL-6 in Leishmania-infected macrophages, eliminating the parasites via a nitric oxide-independent mechanism. This new formulation proved to be a safe and effective treatment for murine leishmaniasis that could be a useful candidate against visceral leishmaniasis.

Current status on prevention and treatment of canine leishmaniasis

Canine leishmaniasis (CanL) is a parasite-borne disease mainly induced by Leishmania infantum in the Old World and Leishmania chagasi (infantum) in the New World. CanL is a zoonosis transmitted by the bite of infected Phlebotominae flies that act as vectors. CanL is a very serious disease that usually produces death when remains untreated and can be a focus of transmission to other dogs or humans. Infected dogs and other domestic and wild animals act as reservoirs and are a real threat to uninfected/healthy dogs and humans in endemic areas where the sand flies are present. Prevention of new infections in dogs can help to stop the current increase of the disease in humans, reinforcing the concept of "One Health" approach. The management of CanL is being performed using prophylactic measures in healthy dogs - insecticides impregnated in collars or immunostimulants applied by spot-on devices - and chemotherapy in animals that suffer from the disease. Antimonials as first-line monotherapy have proven efficacy in reducing most of the clinical signs of CanL, but they need to be administered during several days, and no complete parasite clearance is achieved, favouring the presence of relapses among treated dogs. Therefore, new drugs, such as miltefosine, or combinations of this drug or antimonials with allopurinol are in the pipeline of clinical treatment of CanL. Recently, there has been an emergence of protective - prophylactic - and curative - autogenous vaccines - immunotherapy tools to face CanL, whose results are still under study. This review highlights the current use of preventive and eradicative weapons to fight against this disease, which is a scourge for dogs and a continuous threat to human beings.

In-vitro sensitivity of Pakistani Leishmania tropica field isolate against buparvaquone in comparison to standard anti-leishmanial drugs

In this study, in vitro anti-leishmanial activity of buparvaquone was evaluated against promastigotes and intracellular amastigotes of Pakistani Leishmania tropica isolate KWH23 in relation to the current standard chemotherapy for leishmaniasis (sodium stibogluconate, sodium stibogluconate, amphotericin B and miltefosine). For buparvaquone, mean % inhibition in intracellular amastigotes at four different concentrations (1.35 µM, 0.51 µM, 0.17 µM and 0.057 µM) was 78%, 44%, 20% and 14% respectively, whereas, against promastigotes it was 89%, 77%, 45% and 35% respectively. IC50 values calculated to estimate the anti-leishmanial activity of buparvaquone against intra-cellular amastigotes and promastigotes was 0.53 µM (95% C.I. = 0.32-0.89) and 0.15 µM (95% C.I. = 0.01-1.84) respectively. Amphotericin B was the most potent in-vitro drug tested, with an IC50 of 0.075 µM (95% C.I. = 0.006-0.907) against promastigotes, and 0.065 µM (95% C.I. = 0.048-0.089) against intra-cellular amastigotes. Amphotericin B was more cytotoxic against THP1 cells, with an IC50 of 0.15 µM (95% C.I. = 0.01-0.95) and an apparent in-vitro therapeutic index of 2.0, than was buparvaquone, with an IC50 of 12.03 µM (95% C.I. = 5.36-26.96) against THP1 cells and a therapeutic index of 80.2. The study proposes that buparvaquone may be further investigated as a candidate drug for treatment of cutaneous leishmaniasis.

Effectiveness of liposomal buparvaquone in an experimental hamster model of Leishmania (L.) infantum chagasi

The objective of this study was to develop a novel liposomal formulation, containing phosphatidylserine (PS), of buparvaquone (BPQ) and to evaluate its in vivo effectiveness in Leishmania (L.) infantum chagasi-infected hamsters. The activity of BPQ was evaluated against both the promastigote forms of different Leishmania species and the intracellular amastigotes of L. (L.) infantum chagasi. Buparvaquone was entrapped in PS-liposomes (BPQ-PS-LP), and the drug was quantified by ultra-high-performance liquid chromatography. The treatment was quantified by detecting the RNA of the living amastigotes in the spleen and the liver by real-time PCR. In vitro assays with L. (L.) infantum chagasi intracellular amastigotes were performed in peritoneal macrophages for the evaluation of the 50% inhibitory concentration (IC(50)). BPQ-PS-LP at 0.33 mg/kg/day for eight consecutive days reduced the number of amastigotes by 89.4% (P<0.05) in the spleen and by 67.2% (P>0.05) in the liver, compared to 84.3% (P<0.05) and 99.7% (P<0.05), respectively, following Glucantime® treatment at 50 mg/kg/day. Free BPQ at 20 mg/kg/day failed to treat the hamsters when compared to the untreated group. BPQ was significantly (P<0.05) selective against L. (L.) infantum chagasi intracellular amastigotes, with an IC(50) value of 1.5 μM; no in vitro mammalian cytotoxicity could be detected. Other cutaneous species were also susceptible to BPQ, with IC(50) values in the range 1-4 μM. BPQ-PS-LP caused a significant reduction in the parasite burden at a 60-fold lower dose than did the free BPQ. These results show the potential of PS-liposome formulations for the successful targeted delivery of BPQ in visceral leishmaniasis.

Topical buparvaquone formulations for the treatment of cutaneous leishmaniasis

As the part of a study to develop buparvaquone (BPQ) formulations for the treatment of cutaneous leishmaniasis, the topical delivery of BPQ and one of its prodrugs from a range of formulations was evaluated. In previous studies, BPQ and its prodrugs were shown to be potent antileishmanials in-vitro, with ED50 values in the nanomolar range. 3-Phosphono-oxymethyl-buparvaquone (3-POM-BPQ) was the most potent antileishmanial and was chosen, together with the parent drug, for further investigation. The ability of the parent and prodrug formulations to cross human and murine skin was tested in-vitro using the Franz diffusion cells. Formulations intended for topical application containing either BPQ or 3-POM-BPQ were developed using excipients that were either acceptable for topical use (GRAS or FDA inactive ingredients) or currently going through the regulatory process. BPQ was shown to penetrate both human epidermal membranes and full thickness BALB/c skin from a range of formulations (gels, emulsions). Similarly, 3-POM-BPQ penetrated full-thickness BALB/c skin from several gel formulations. In-vitro binding studies showed that BPQ bound melanin in a dose-dependent manner and preferably bound to delipidized skin over untreated BALB/c skin (on a weight to weight basis). The results confirm that BPQ and its prodrug 3-POM-BPQ can penetrate the skin from several formulations, making them potentially interesting candidates for further investigation of topical formulations using in-vivo models of cutaneous leishmaniasis.

Development and validation of RP-HPLC-UV method for simultaneous determination of buparvaquone, atenolol, propranolol, quinidine and verapamil: A tool for the standardization of rat in situ intestinal permeability studies

A simple, sensitive and specific reversed phase high performance liquid chromatographic (RP-HPLC) method with UV detection at 251 nm was developed for simultaneous quantitation of buparvaquone (BPQ), atenolol, propranolol, quinidine and verapamil. The method was applicable in rat in situ intestinal permeability study to assess intestinal permeability of BPQ, a promising lead compound for Leishmania donovani infections. The method was validated on a C-4 column with mobile phase comprising ammonium acetate buffer (0.02 M, pH 3.5) and acetonitrile in the ratio of 30:70 (v/v) at a flow rate of 1.0 ml/min. The retention times for atenolol, quinidine, propranolol, verapamil and BPQ were 4.30, 5.96, 6.55, 7.98 and 8.54 min, respectively. The calibration curves were linear (correlation coefficient > or =0.996) in the selected range of each analyte. The method is specific and sensitive with limit of quantitation of 15 microg/ml for atenolol, 0.8 microg/ml for quinidine, 5 microg/ml for propranolol, 10 microg/ml for verapamil and 200 ng/ml for BPQ. The validated method was found to be accurate and precise in the working calibration range. Stability studies were carried out at different storage conditions and all the analytes were found to be stable. This method is simple, reliable and can be routinely used for accurate permeability characterization.

Treatment of canine Old World visceral leishmaniasis: a systematic review

Canine visceral leishmaniasis is a systemic disease caused by Leishmania infantum. The aim of this systematic review was to identify and evaluate the evidence of efficacy of interventions for treatment or prevention of canine visceral leishmaniasis, and to propose recommendations for or against their use. Forty-seven articles describing clinical trials published between 1980 and 2004 fulfilled selection criteria. The evaluation of clinical trials provided good evidence for recommending the use of meglumine antimoniate at a minimum dosage of 100 mg kg(-1) daily for at least 3-4 weeks, combined with allopurinol in order to obtain a good clinical efficacy and a reduced relapse rate. The evaluation of the articles also provided fair evidence for recommending the use of pentamidine (4 mg kg(-1) twice weekly) and aminosidine (5 mg kg(-1) twice daily) for 3-4 weeks. There was insufficient evidence for recommending the use of allopurinol alone, amphotericin B, buparvaquone, ketoconazole, enrofloxacin, and the combinations of metronidazole with spiramicyn or metronidazole with enrofloxacin. Fair evidence against the use of aminosidine at high dosages (20-80 mg kg(-1) per day) was proposed due to its side effects. Evaluation of articles on repellent measures against sand fly vectors of leishmaniasis provided good evidence for recommending deltamethrin collars and fair evidence for recommending spot-on permethrin.

Clinical and serological follow-up in dogs with visceral leishmaniosis treated with allopurinol and sodium stibogluconate

Seven dogs with parasitologically proven clinical visceral leishmaniosis (Leishmania infantum infection) were treated with a combination of allopurinol and sodium stibogluconate. The dogs received first orally 15 mg/kg of allopurinol every 12 h until the clinical signs improved, in the following 1 month period allopurinol at same dose and subcutaneously 30 mg/kg of sodium stibogluconate combination were given daily and at the end of the combined treatment, allopurinol was continued alone at the same dose till the end of 8 months. During the treatment period, dogs were supported by additional proteins, vitamins, and minerals. A long acting insecticide (collar or drop) was also used in order to prevent further parasite transmission. Follow-up was maintained by clinical, clinicopathological evaluation, and parasitological examination of lymph node, serology using the indirect immunofluorescent antibody test (IFAT). Before treatment commenced, the most important clinical signs were exfoliative dermatitis, ulcerations, peripheral lymhadenopathy, pale mucous membranes, weight loss, and ocular lesions. Clinicopathological findings included commonly anaemia, hyperproteinaemia, hyperglobulinaemia and hypoalbuminaemia. Before the treatment, amastigotes were seen in six of the seven dogs by examination of lymph node aspiration, and IFAT-titers were positive in all dogs. At the end of 8 months treatment, remission of clinical signs, restoration to normal of clinicopathological abnormalities were noticed. Lymph node aspiration was performed on three out of the seven dogs at the end of the treatment because of the very small sizes of the lymph nodes, and no amastigotes were observed. Although the mean IFAT-titer of the dogs were significantly (P < 0.001) lower compared with pretreatment, IFAT-titers of dogs were still positive. No relapses occurred during treatment period and a 6-24-month duration after the end of therapy. Based on the above results, long-term use of allopurinol combined with sodium stibogluconate together with support treatment concluded to have enough therapeutic efficacies in the treatment of dogs with visceral leishmaniosis. Observations of the cases for possible relapses were still going on and insecticide application was carefully carrying on in order preventing a possible re-infection.

Chemotherapy of canine leishmaniosis

Visceral leishmaniosis is a widespread and potentially fatal disease of dogs and humans common in the Mediterranean region, the Middle East, and South America. Canine leishmaniosis is most frequently treated with the drugs meglumine antimoniate, allopurinol, amphotericin B, or a combination of meglumine antimoniate and allopurinol. Therapy with the currently used drugs often achieves temporary clinical improvement and changes in immunologic parameters with restoration of the ability to mount parasite-specific cell mediated responses and decrease in anti-leishmanial antibody titers. However, treatment usually does not prevent relapse of disease or eliminate parasite carriage. Due to the current lack of an ultimate and effective therapy for canine leishmaniosis, new drugs, delivery systems and treatment strategies are necessary to achieve a consistent parasitological cure in infected dogs.