Mónica C. García

A novel gel based on an ionic complex from a dendronized polymer and ciprofloxacin: Evaluation of its use for controlled topical drug release

The development and characterization of a novel, gel-type material based on a dendronized polymer (DP) loaded with ciprofloxacin (CIP), and the evaluation of its possible use for controlled drug release, are presented in this work. DP showed biocompatible and non-toxic behaviors in cultured cells, both of which are considered optimal properties for the design of a final material for biomedical applications. These results were encouraging for the use of the polymer loaded with CIP (as a drug model), under gel form, in the development of a new controlled-release system to be evaluated for topical administration. First, DP-CIP ionic complexes were obtained by an acid-base reaction using the high density of carboxylic acid groups of the DP and the amine groups of the CIP. The complexes obtained in the solid state were broadly characterized using FTIR spectroscopy, XRP diffraction, DSC-TG analysis and optical microscopy techniques. Gels based on the DP-CIP complexes were easily prepared and presented excellent mechanical behaviors. In addition, optimal properties for application on mucosal membranes and skin were achieved due to their high biocompatibility and acute skin non-irritation. Slow and sustained release of CIP toward simulated physiological fluids was observed in the assays (in vitro), attributed to ion exchange phenomenon and to the drug reservoir effect. An in vitro bacterial growth inhibition assay showed significant CIP activity, corresponding to 38 and 58% of that exhibited by a CIP hydrochloride solution at similar CIP concentrations, against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. However, CIP delivery was appropriate, both in terms of magnitude and velocity to allow for a bactericidal effect. In conclusion, the final product showed promising behavior, which could be exploited for the treatment of topical and mucosal opportunistic infections in human or veterinary applications.

CD73 Inhibition Shifts Cardiac Macrophage Polarization toward a Microbicidal Phenotype and Ameliorates the Outcome of Experimental Chagas Cardiomyopathy

Increasing evidence demonstrates that generation of extracellular adenosine from ATP, which is hydrolyzed by the CD39/CD73 enzyme pair, attenuates the inflammatory response and deactivates macrophage antimicrobial mechanisms. Although CD73 is emerging as a critical pathway and therapeutic target in cardiovascular disorders, the involvement of this ectonucleotidase during myocardial infection has not been explored. Using a murine model of infection with Trypanosoma cruzi, the causal agent of Chagas cardiomyopathy, we observed a sudden switch from the classical M1 macrophage (microbicidal) phenotype toward an alternative M2 (repairing/anti-inflammatory) phenotype that occurred within the myocardium very shortly after BALB/c mice infection. The observed shift in M1/M2 rate correlated with the cardiac cytokine milieu. Considering that parasite persistence within myocardium is a necessary and sufficient condition for the development of the chronic myocarditis, we hypothesized that CD73 activity may counteract cardiac macrophage microbicidal polarization, rendering the local immune response less effective. In fact, a transient treatment with a specific CD73 inhibitor (adenosine 5′-α,β-methylene-diphosphate) enhanced the microbicidal M1 subset predominance, diminished IL-4– and IL-10–producing CD4+ T cells, promoted a proinflammatory cytokine milieu, and reduced parasite load within the myocardium during the acute phase. As a direct consequence of these events, there was a reduction in serum levels of creatine kinase muscle–brain isoenzyme, a myocardial-specific injury marker, and an improvement in the electrocardiographic characteristics during the chronic phase. Our results demonstrate that this purinergic system drives the myocardial immune response postinfection and harbors a promising potential as a therapeutic target.

Clomipramine and Benznidazole Act Synergistically and Ameliorate the Outcome of Experimental Chagas Disease

ABSTRACT Chagas disease is an important public health problem in Latin America, and its treatment by chemotherapy with benznidazole (BZ) or nifurtimox remains unsatisfactory. In order to design new alternative strategies to improve the current etiological treatments, in the present work, we comprehensively evaluated the in vitro and in vivo anti-Trypanosoma cruzi effects of clomipramine (CMP) (a parasite-trypanothione reductase-specific inhibitor) combined with BZ. In vitro studies, carried out using a checkerboard technique on trypomastigotes (T. cruzi strain Tulahuen), revealed a combination index (CI) of 0.375, indicative of a synergistic effect of the drug combination. This result was correlated with the data obtained in infected BALB/c mice. We observed that during the acute phase (15 days postinfection [dpi]), BZ at 25 mg/kg of body weight/day alone decreased the levels of parasitemia compared with those of the control group, but when BZ was administered with CMP, the drug combination completely suppressed the parasitemia due to the observed synergistic effect. Furthermore, in the chronic phase (90 dpi), mice treated with both drugs showed less heart damage as assessed by the histopathological analysis, index of myocardial inflammation, and levels of heart injury biochemical markers than mice treated with BZ alone at the reference dose (100 mg/kg/day). Collectively, these data support the notion that CMP combined with low doses of BZ diminishes cardiac damage and inflammation during the chronic phase of cardiomyopathy. The synergistic activity of BZ-CMP clearly suggests a potential drug combination for Chagas disease treatment, which would allow a reduction of the effective dose of BZ and an increase in therapeutic safety.

Bioadhesive and biocompatible films as wound dressing materials based on a novel dendronized chitosan loaded with ciprofloxacin

The bioadhesive polymeric films as topical drug delivery systems are interesting alternatives to improve the pharmacotherapy and patient compliances. New derivate biomaterials based on weisocyanate- dendronized PVP- crosslinked chitosan and loaded with ciprofloxacin (CIP), as model drug, were used to prepare bioadhesive films. Relevant in vitro/in vivo attributes to define main physicochemical and biopharmaceutical characteristics for topical wound-healing applications were evaluated. A high proportion of CIP, uniformly dispersed along throughout the film, was loaded. An extended release of CIP and different behaviors of release profiles, depending on the presence of dendron, were observed. The films loaded with CIP were effective in inhibiting the growth of both Gram positive and Gram negative bacteria. In addition, biocompatibility and bioadhesion into conjuntival-sacs of the rabbits suggests that these films have good properties to be applied over skin wounds for topical applications, allowing a reduction of the frequency of administration and improving the residence time of the films.

Extemporaneous benznidazole oral suspension prepared from commercially available tablets for treatment of Chagas disease in paediatric patients

To develop an extemporaneous 1% benznidazole (BNZ) suspension, with masked taste and adequate stability starting from available commercial tablets. The quality of compounding was evaluated through content uniformity measurement and physical and microbiological stability evaluation, under different storage conditions during 90 days.

Development and characterization of miltefosine-loaded polymeric micelles for cancer treatment

Miltefosine presents antineoplastic activity but high hemolytic potential. Its use in cancer has been limited to treating cutaneous metastasis of breast cancer. To decrease hemolytic potential, we developed a formulation of miltefosine-loaded polymeric micelles (PM) of the copolymer Pluronic-F127. A central composite design was applied and the analysis of variance showed that the optimum level of hydrodynamic diameter and polydispersity index predicted by the model and experimentally confirmed were 29nm and 0.105, respectively. Thermal analyses confirmed that miltefosine was molecularly dispersed within PM. Pluronic-F127 PM with miltefosine 80μM presented a significant reduction of hemolytic effect (80%, p<0.05) in comparison to free drug. In vitro assays against HeLa carcinoma cells demonstrated similar cytotoxicity to free miltefosine and PM. Our results suggest that, by lowering hemolytic potential, miltefosine-loaded Pluronic-F127 PM a promising alternative to broaden this drug use in cancer therapy, as well as of other alkylphosphocholines.

Polysaccharides-based multiparticulated interpolyelectrolyte complexes for controlled benznidazole release

ABSTRACT Polysaccharides‐based delivery systems and interpolyelectrolyte complexes (IPECs) are interesting alternatives to control the release of drugs, thereby improving therapies. Benznidazole (BZ) is the selected drug for Chagas disease pharmacotherapy. However, its side effects limit its efficacy and safety. We developed novel multiparticulated BZ‐loaded IPECs based on chitosan and alginic acid, and investigated their physicochemical and pharmacotechnical properties. IPECs were obtained using the casting solvent method, followed by wet granulation. They presented ionic interaction between the biopolymers, revealed that free BZ was uniformly distributed and showed adequate flow properties for hard gelatin‐capsule formulation. The multiparticles exhibited mucoadhesion properties and revealed modulation of BZ release, depending on the release media, in accordance with the fluid uptake. The IPECs developed possess interesting properties that are promising for the design of novel alternatives to improve Chagas disease pharmacotherapy, which would diminish BZ’s adverse effects and/or allow a reduction in the frequency of BZ administration.

Multi-kinetic release of benznidazole-loaded multiparticulate drug delivery systems based on polymethacrylate interpolyelectrolyte complexes

&NA; Interpolyelectrolyte complexes (IPEC) formulated as multiparticulate drug delivery systems (MDDS) are interesting carriers to improve drug’ performance. Benznidazole (BZ) is the first–line drug for Chagas treatment; however, it presents side effects and toxicity, conditioning its efficacy and safety. The goal of this work was to obtain novel MDDS composed by IPEC based on different polymethacrylate carriers loaded with BZ and to investigate in vitro drug delivery performance for oral administration. Physicochemical characterizations were studied and preclinical studies in a murine model of acute Chagas disease were also performed. The MDDS composed by BZ‐loaded IPEC based on polymethacrylates were obtained by casting solvent followed by wet granulation methods with yields >83%. FT‐IR demonstrated ionic interaction between the polyelectrolytes. Confocal microscopy, DSC and PXRD revealed a fraction uniformly distributed of free BZ on the multiparticles. The rheological evaluation of the MDDS showed adequate flow features for their formulation in hard gelatin‐capsules. The type and composition of IPEC conditioned the modulation of BZ release and fluid uptake results. MDDS based on more hydrophylic Eudragit® showed very fast dissolution (Q15min > 85%), while an extended release (Q120min ≤ 40%) for the hydrophobic ones was observed. Capsules containing a combination of two MDDS with different release profile of BZ showed promising properties to improve Chagas disease pharmacotherapy in the preliminary in vivo assay performed, in which the BZ‐loaded MDDS exhibited efficacy to reduce parasitemia, while decreasing the levels of liver injury markers in comparison to BZ conventional treatment. Multi‐kinetic BZ delivery systems developed are interesting pharmaceutical alternatives to improve the treatment of Chagas disease. Graphical abstract Figure. No Caption available.

Stimulus-responsive nanogels for drug delivery

Abstract Nanogels have attracted growing interest in the last five decades owing to their potential for biomedical applications, including drug delivery systems and bioimaging. They are able to encapsulate high amounts of biologically active agents such as drugs, proteins, and genetic material inside the polymer networks and release them in a controlled manner. Internal and external microenvironmental factors such as pH, ionic force, magnetic field, temperature, enzyme, glucose, redox potential, light, or a combination of them, can stimulate the response of nanogels and are useful for the controlled release of bioactive compounds. This chapter aims to cover the main features regarding the most outstanding contributions in the area of drug delivery from stimulus responsive nanogels. The recent advances in their main biomedical applications and physicochemical attributes for potential application of nanogels in cancer treatment will be highlighted.

Drug delivery systems based on nonimmunogenic biopolymers

Abstract Biopolymers have attracted considerable interest for the development of drug delivery systems (DDSs) owing to their biocompatibility, nontoxicity, renewability, and mild processing conditions. These polymers are degradable in vivo, either enzymatically or nonenzymatically, and can be metabolized and excreted via normal physiological pathways. Application of biopolymers in living systems would reduce immunological reactions and toxicity that occur when a synthetic polymer is used in a host. There are currently many different biopolymers reported in the literature that have been evaluated for use in the development of DDSs. In this context, this chapter presents the outstanding contributions in the area of biopolymeric nanoparticles as DDSs, including the main types of biopolymers used in their preparation.