Effectiveness of an O-Alkyl Hydroxamate in Dogs with Naturally Acquired Canine Leishmaniosis: An Exploratory Clinical Trial.

Canine leishmaniosis is a challenge in veterinary medicine and no drug to date has achieved parasite clearance in dogs. Histone deacetylase inhibitors are a drug class widely used in cancer chemotherapy. We have successfully used O-alkyl hydroxamates (vorinostat derivatives) in the treatment of a laboratory model of visceral leishmaniasis without showing toxicity. In order to test the effectiveness of a particular compound, MTC-305, a parallel-group, randomized, single-centre, exploratory study was designed in naturally infected dogs. In this clinical trial, 18 dogs were allocated into 3 groups and were treated with either meglumine antimoniate (104 mg SbV/kg), MTC-305 (3.75 mg/kg) or a combination of both using a lower MTC-305 dose (1.5 mg/kg) through a subcutaneous route for 2 treatment courses of 30 days, separated by a 30-day rest period. After treatment, a follow-up time of 4 months was established. Parasite burden in bone marrow, lymph node and peripheral blood were quantified through qPCR. Antibody titres were determined through an immunofluorescence antibody test, and cytokine expression values were calculated through RT-qPCR. Treatment safety was evaluated through the assessment of haematological and biochemical parameters in blood, weight, and gastrointestinal alterations. Assessment was carried out before, between and after treatment series. Treatment with MTC-305 was effective at reducing parasite burdens and improving the animals' clinical picture. Dogs treated with this compound did not present significant toxicity signs. These results were superior to those obtained using the reference drug, meglumine antimoniate, in monotherapy. These results would support a broader clinical trial, optimised dosage, and an expanded follow-up stage to confirm the efficacy of this drug.

O-Alkyl Hydroxamates Display Potent and Selective Antileishmanial Activity.

Leishmania (L.) infantum causes visceral, cutaneous, and mucosal leishmaniasis in humans and canine leishmaniasis in dogs. Herein, we describe that O-alkyl hydroxamate derivatives displayed potent and selective in vitro activity against the amastigote stage of L. infantum while no activity was observed against promastigotes. Compound 5 showed potent in vivo activity against L. infantum. Moreover, the combination of compound 5 supported on gold nanoparticles and meglumine antimoniate was also effective in vivo and improved the activity of these compounds compared to that of the individual treatment. Docking studies showed that compound 5 did not reach highly conserved pocket C and established interactions with the semiconserved residues V44, A45, R242, and E243 in pocket A of LiSIR2rp1. The surface space determined by these four amino acids is not conserved in human sirtuins. Compound 5 represents a new class of selective ligands with antileishmanial activity.

A nanodelivered Vorinostat derivative is a promising oral compound for the treatment of visceral leishmaniasis.

There is currently no satisfactory treatment for visceral leishmaniasis; the disease is thus in desperate need of novel drugs. The ideal candidate should be effective, safe, affordable, and administered via the oral route. Histone deacetylases (HDACs) are involved in silencing critical regulatory pathways, including pro-apoptotic programs, and represent potential therapeutic targets for pharmacological interventions. O-alkyl hydroxamates have traditionally been considered to exert no effect on mammal HDACs. The aim of this study was to evaluate the effect of MDG, a SAHA derivative of the O-alkyl hydroxamate family with no activity on human histone deacetylase enzymes, on the visceral leishmaniasis causative agents and in a murine model of the disease. The effects of vorinostat, tubacin and valproic acid (well-known mammal HDAC inhibitors) on the parasite were also evaluated. MDG was found to be highly active against Leishmania infantum and L. donovani intracellular amastigotes in vitro but not against the promastigote stage. In contrast, vorinostat, tubacin and valproic acid showed no activity against the parasite. Assays investigating hERG and Cav1.2 channels in vitro found no evidence of MDG-driven cardiotoxicity. MDG showed neither hepatotoxicity nor mutagenicity, nor did it exert activity on cytochrome P450 enzymes. MDG was adsorbed onto gold nanoparticles for the in vivo experiments, performed on infected Balb/c mice. MDG was effective at reducing the parasite load in major target tissues (bone marrow, spleen and liver) in more than 70% at 25 mg/kg through both the oral and intraperitoneal route, proving more active than the reference compounds (meglumine antimoniate, MA) without showing toxicity. In addition, the combination of MDG and MA was very effective.

Development and Characterization of Magnetite/Poly(butylcyanoacrylate) Nanoparticles for Magnetic Targeted Delivery of Cancer Drugs.

A great attention is presently paid to the design of drug delivery vehicles based on surface-modified magnetic nanoparticles. They can, in principle, be directed to a desired target area for releasing their drug payload, a process triggered by pH, temperature, radiation, or even magnetic field. To this, the possibility of forming part of diagnostic tools by enhanced magnetic resonance imaging or that of further treatment by magnetic hyperthermia can be added. Bare particles are rapidly eliminated from the bloodstream by the phagocyte mononuclear system, leading to short biological half-life. It is hence required to coat them in order to increase their biocompatibility and facilitate the drug incorporation. In this work, magnetite nanoparticles were coated with poly(butylcyanoacrylate) (PBCA) manufactured and characterized with regard to their physical properties and their suitability as a platform for magnetically controlled drug delivery. The average diameter of magnetite and core-shell nanoparticles was 97 ± 19 and 140 ± 20 nm, respectively. Infrared analysis, electrophoretic mobility, surface thermodynamics analysis, and X-ray diffraction all confirmed that the magnetic particles were sufficiently covered by the polymer in the composite nanoparticles. In addition, assays using normal (CCD-18 and MCF-10A) and tumoral (T-84 and MCF-7) cell lines derived from colon and breast tissue, respectively, demonstrated that nanocomposites have low or negligible cytotoxicity. It is concluded that PBCA-coated magnetite core-shell nanoparticles represent a remarkable promise as a platform for magnetically controlled drug delivery.

Design and characterization of a magnetite/PEI multifunctional nanohybrid as non-viral vector and cell isolation system.

It is described the reproducible formulation and complete physicochemical characterization of nanohybrids based on magnetite (Fe3O4) cores embedded within a polyethylenimine (PEI) matrix. Particle size, surface electrical charge, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) analyses, and magnetic field-responsive behaviour characterizations defined that the 4:3 (Fe3O4:PEI) weight proportion led to the best production performances of magnetically responsive nanocomposites in which the magnetic nuclei are completely covered by the polymeric shell. Agarose gel electrophoresis assays demonstrated the capacity of the Fe3O4/PEI particles to condense, release, and protect the DNA against enzymatic degradation. In vitro assays were performed to evaluate the transfection efficiency (up to 4.5% of transfected HEK-293 cells at a 10/1 PEI/DNA ratio), iron absorption by D1-mesenchymal stem cells (D1-MSCs, high values after only 15min of magnetic incubation), influence on metabolic activity (negligible effect up to 44µg nanocomposites/105 cells), and cell isolation capacity of the core/shell particles (significant increase in the retention of D1-MSCs transduced with green fluorescent protein). The Fe3O4/PEI nanohybrids hold promising characteristics suggestive of their capacity for transfection and cell isolation applications.

Topical Treatment of Leishmania tropica Infection Using (-)-α-Bisabolol Ointment in a Hamster Model: Effectiveness and Safety Assessment.

There is currently no reliable treatment for the management of cutaneous leishmaniasis, and intralesional antimonial injections remain the main treatment. The present work aims at evaluating the antileishmanial effectiveness and safety of (-)-α-bisabolol (1) in a novel topical formulation on a cutaneous leishmaniasis model involving Leishmania tropica-infected Syrian hamsters. The topical treatment with 1 reduced lesion thickness to 56% at 2.5%, showing a higher efficacy than the reference control, meglumine antimoniate. Other regimens (ointment at 1% and 5% and oral treatment at 200 mg/kg) reduced the footpad thickness as well. The skin parasite load decreased after the experiment in all treatment groups, particularly in those animals treated with the 2.5% formulation (83.2%). Treatment with (-)-α-bisabolol at different concentrations or through an oral route did not lead to the appearance of toxicity or side effects in healthy hamsters or infected animals. Therefore, topical (-)-α-bisabolol was more effective than meglumine antimoniate in this cutaneous leishmaniasis model without showing toxicity effects on the hamsters. These results are of great interest and might be used for the development of alternatives for the treatment of cutaneous leishmaniasis, either in monotherapy or in combination with other drugs whose skin permeability could be enhanced by this sesquiterpene.

Synthesis of a biodegradable magnetic nanomedicine based on the antitumor molecule tegafur.

The introduction of magnetic nanocarriers in chemotherapy aims to enhance the anticancer activity of antitumor molecules whereas keeping their toxicity to a very minimum. Magnetite/poly(hexylcyanoacrylate) (core/shell) nanoplatforms were synthesized by an emulsion/polymerization procedure. An exhaustive physicochemical characterization (including infrared spectrometry, electrophoresis, and thermodynamic analysis) suggested that the magnetite nuclei were embedded into a polymeric nanomatrix. The very good magnetic responsiveness of such core/shell nanoparticles was defined by the hysteresis cycle. To improve the intravenous delivery of tegafur to cancer, we investigated its incorporation into the nanoplatform. Compared to surface adsorption, drug entrapment into the polymeric shell yielded higher tegafur loading values, and a much slower release profile. A high frequency alternating magnetic gradient was used to elucidate the heating characteristics of the nanoparticles: a stable maximum temperature of 46 °C was successfully achieved within 32 min. Thus, we put forward that such kind of multifunctional nanomedicine hold very important characteristics (i.e., high drug loading, little burst release, hyperthermia, and magnetically targeted tegafur delivery), suggestive of its potential for combined antitumor therapy against cancer.

Chitosan nanoparticles as a new delivery system for the chemotherapy agent tegafur.

BACKGROUND: Despite the very efficient antitumor activity of conventional chemotherapy, generally high doses of anticancer molecules must be administered to obtain the required therapeutic action, simultaneously leading to severe side effects. This is frequently a consequence of the development of multidrug resistance by cancer cells and of the poor pharmacokinetic profile of these agents. OBJECTIVE: In Order to improve the antitumor effect of tegafur and overcome their important drawbacks, we have investigated its incorporation into a drug nanoplatform based on the biodegradable polymer chitosan. MATERIALS AND METHODS: Two tegafur loading methods were studied: (i) absorption into the polymeric network (entrapment procedure); and (ii) surface deposition (adsorption procedure) in already formed chitosan nanoparticles. RESULTS: Tegafur entrapment into the polymeric matrix has yielded higher drug loading values and a slower drug release profile, compared to single surface adsorption. The main factores determining the drug loading to chitosan were identified. DISCUSSION AND CONCLUSION: Such polymeric colloid present very interesting properties for efficient tegafur delivery to cancer.

Iron/ethylcellulose (core/shell) nanoplatform loaded with 5-fluorouracil for cancer targeting.

Even though 5-fluorouracil has been demonstrated to display antitumor activity against a wide variety of cancers, high doses are needed to bring out the required therapeutic activity that could simultaneously lead to severe side effects. We hypothesized that the efficient delivery of 5-fluorouracil to tumors using a magnetic nanoplatform could reduce the dose required to obtain sufficient anticancer response. Thus, we have formulated a 5-fluorouracil-loaded magnetic nanomedicine consisting of a magnetic core (iron) and a biocompatible polymeric shell (ethylcellulose). These core/shell nanoparticles were synthesized by an emulsion solvent evaporation process, and 5-fluorouracil loading was assayed by surface incorporation onto the preformed nanocomposites, and by drug incorporation into the magnetic colloid. The contributions of both the surface and the polymeric network to the overall drug loading were investigated by means of optical absorbance and electrophoretic mobility determinations. 5-Fluorouracil entrapment into the polymeric matrix yielded a higher drug loading and a slower drug release profile as compared with drug adsorption. These preliminary results suggest the potential of this stimuli-sensitive drug carrier for cancer targeting.

Formulation and physicochemical characterization of poly(epsilon-caprolactone) nanoparticles loaded with ftorafur and diclofenac sodium.

Even though conventional pharmacotherapy has been demonstrated to display very efficient activity against a wide variety of diseases, several active agents (e.g., anti-tumor drugs and non-steroidal anti-inflammatory drugs) are generally needed to be administered at high doses to elicit the required therapeutic action, simultaneously leading to severe side effects. This fact is usually due to unfavourable pharmacokinetic profiles (poor biological half-life) and to the possibility of induction of resistance. In order to increase the therapeutic activity of ftorafur and diclofenac sodium along with an overcome of their important drawbacks, we investigated their formulation into a colloidal carrier based on the biodegradable polymer poly(epsilon-caprolactone). Two drug loading methods were studied: (i) surface adsorption in already formed nanoparticles after incubation in a drug solution; (ii) drug addition before interfacial polymer disposition leading to drug entrapment into the polymeric network. We hypothesized that such nanocarrier possessed very significant characteristics (e.g., unusually high drug loading and low burst release), suggesting their potential application for efficient drug delivery to targeted sites.

5-Fluorouracil-loaded iron/ethylcellulose (core/shell) nanoparticles for active targeting of cancer.

Even though 5-fluorouracil has been demonstrated to display antitumor activity against a wide variety of cancers, it is needed to be administered at high doses to elicit the required therapeutic activity, simultaneously leading to severe side effects. We hypothesized that the efficient delivery of 5-fluorouracil to tumors using a magnetic colloid could reduce the dose required to bring out sufficient therapeutic response. Thus, we have formulated a 5-fluorouracil-loaded magnetic nanomedicine consisting of a magnetic core (iron) and a biocompatible polymeric shell (ethylcellulose), suitable for parenteral administration. These core/shell nanoparticles were synthesized by an emulsion solvent evaporation process. Two drug loading methods were analyzed: the first one based on 5-fluorouracil surface adsorption onto the preformed nanoparticles, and the second method being drug addition prior to the emulsion solvent evaporation process leading to drug entrapment into the polymeric network. 5-Fluorouracil entrapment into the polymeric matrix yielded a higher drug loading and a slower drug release profile as compared with drug adsorption. Finally, as a proof of concept, Prussian blue staining has demonstrated the considerable accumulation of these magnetically guided composite nanoparticles in the tumors, suggesting the potential of this stimuli-sensitive drug carrier for the efficient treatment of cancer by active targeting.

Development of iron/ethylcellulose (core/shell) nanoparticles loaded with diclofenac sodium for arthritis treatment.

Diclofenac sodium is a non-steroidal anti-inflammatory drug of choice to treat arthritis because of its potential anti-inflammatory and analgesic activity. Because of its shorter biological half-life, it is needed to be given frequently and at high doses to elicit the required therapeutic activity, simultaneously leading to severe side effects. We hypothesized that the efficient delivery of diclofenac sodium to inflammation using a magnetic colloid could reduce the dose required to bring out sufficient therapeutic response. Hence, we have developed a diclofenac sodium-loaded magnetic nanomedicine, consisting of a magnetic core (iron) and a biocompatible polymeric shell (ethylcellulose) for parenteral administration. These core/shell nanoparticles were synthesized by an emulsion solvent evaporation process. Two drug loading methods were analyzed: the first one being drug addition prior to the emulsion solvent evaporation process (leading to drug entrapment into the polymeric network), and the second method based on diclofenac sodium surface adsorption onto the preformed nanoparticles. Compared to drug adsorption, the entrapment of this active agent into the polymeric matrix yielded a higher drug loading and a slower drug release profile. Such nanocomposites possessed very important characteristics such as unusually high drug loading, enhanced magnetic susceptibility and prolonged drug release, indicating their potential use as nanocarriers for efficient delivery of diclofenac sodium to inflammation sites.

Stability of fenbendazole suspensions for veterinary use. Correlation between zeta potential and sedimentation.

In this paper we have carried out a detailed investigation of the stability and redispersibility characteristics of fenbendazole aqueous suspensions, through a thermodynamic and electrokinetic characterization, considering the effect of both pH and ionic strength. The hydrophobic character of the drug, and the surface charge and electrical double-layer thickness play an essential role in the stability of the system, hence the need for a full characterization of fenbendazole. It was found that the drug suspensions displays "delayed" or "hindered" sedimentation, determined by their hydrophobic character and their low zeta potential (indicating a small electrokinetic charge on the particles). The electrostatic repulsion between the particles is responsible for the low sedimentation volume and poor redispersibility of the drug. However, only low concentrations of AlCl(3) induced a significant effect on both the zeta potential and stability of the drug, leading to a "free-layered" sedimentation and a very easy redispersion which could be of great interest in the design of an oral pharmaceutical dosage form for veterinary.

Poly(alkylcyanoacrylate) colloidal particles as vehicles for antitumour drug delivery: a comparative study.

Because of the fundamental importance of new therapeutic routes for cancer treatment, a number of systems based on colloidal particles as vehicles for the delivery of chemotherapeutic agents have been devised. The target is always to provide the proper dose of the antitumour agent only at the desired locus of action, thus reducing the unwanted side effects. The systems studied in this work are nanospheres of the biodegradable polymers poly(ethyl-2-cyanoacrylate), poly(butylcyanoacrylate), poly(hexylcyanoacrylate) and poly(octylcyanoacrylate), all suitable for parenteral administration, as vehicles for 5-fluorouracil, a well studied drug used for the treatment of solid tumours. Two loading methods have been analyzed: the first one is based on drug addition during the process of generation of the particles, by an anionic emulsion/polymerization procedure, and the subsequent drug trapping in the polymeric network. The second method is based on surface adsorption in already formed nanoparticles, after incubation in the drug solution. A detailed investigation of the capabilities of the polymer particles to load this drug is described. The main factors determining the drug incorporation to the polymer network were the type of monomer, the pH and the drug concentration. The release kinetics of 5-fluorouracil is found to be controlled by the pH of the release medium, the type of drug incorporation and the type of polymer.