Nanosystems for gene therapy targeting brain damage caused by viral infections.

Several human pathogens can cause long-lasting neurological damage. Despite the increasing clinical knowledge about these conditions, most still lack efficient therapeutic interventions. Gene therapy (GT) approaches comprise strategies to modify or adjust the expression or function of a gene, thus providing therapy for human diseases. Since recombinant nucleic acids used in GT have physicochemical limitations and can fail to reach the desired tissue, viral and non-viral vectors are applied to mediate gene delivery. Although viral vectors are associated to high levels of transfection, non-viral vectors are safer and have been further explored. Different types of nanosystems consisting of lipids, polymeric and inorganic materials are applied as non-viral vectors. In this review, we discuss potential targets for GT intervention in order to prevent neurological damage associated to infectious diseases as well as the role of nanosized non-viral vectors as agents to help the selective delivery of these gene-modifying molecules. Application of non-viral vectors for delivery of GT effectors comprise a promising alternative to treat brain inflammation induced by viral infections.

Development of a validation protocol method for nucleic acid testing to detect human immunodeficiency virus, hepatitis C virus, and hepatitis B virus.

The concern about the risks of viral infections transmission through blood transfusion has led into a search for improvements on screening tests used for the selection of blood donors. Molecular biology techniques applied in researches of viral genomes, known as Nucleic Acid-amplification-Test (NAT), represent a technology capable of increasing transfusion safety by shortening the diagnostic window period. In Brazil, the implementation of this technology for the detection of HIV, HCV and HBV occurred due to the implantation of the NAT Kit - produced by Immunobiological Technology Institute (Biomanguinhos-FIOCRUZ), in the Brazilian blood centers. The National Health Surveillance Agency attaches great importance to validation, since it standardizes, disciplines and regulates criteria for the registration of health products. This work aims to establish a protocol of performance validation by real-time PCR method, taking as the object of study the Bio-Manguinhos NAT Kit, in order to update the product registration or to meet any future needs to ensure all regulatory requirements for the performance validation of the real-time PCR diagnostic kit. The protocol developed followed the ICH recommendations. The results revealed that the adopted methodology contemplates the necessary requirements for compliance with the Brazilian legislation, as well as the established validation parameters.

In Silico studies of novel Sildenafil self-emulsifying drug delivery system absorption improvement for pulmonary arterial hypertension.

Sildenafil is a potent selective inhibitor of phosphosdiesterase-5 previously used in erectile dysfunction and subsequently approved in 2005 for pulmonary arterial hypertension treatment. Since oral administration of sildenafil shows pharmacokinetic problems with mean absolute bioavailability of 41%, the goal of this work was to develop a novel sildenafil self-emulsifying drug delivery system (SEDDS) for oral absorption improvement and management of dosage. One pharmaceutical solution and four SEDDS containing sildenafil were successfully obtained and SEDDS formed O/W nanoemulsion with droplet size less than 300 nm. The stability studies evidenced that the SEDDS containing 3.3% w/w of sildenafil yielded the best results. The safety of 2-pyrrolidone/isobutanol in oral formulations was assessed in mice and no lethality was achieved in the placebo groups with LD50 of 490 mg/Kg for SEDDS II-3.3, suggesting it as a safe excipient for humans. Therewithal, in silico studies using PBPK models provided the pharmacokinetic profile of sildenafil SEDDS. Subsequently, in silico evaluation indicated that the sildenafil SEDDS droplet size influenced its bioavailability, enhancing absorption, assuring a good pharmacokinetic profile. These findings suggest that the formulations developed here presented the potential to enhance drug oral absorption with the possibility to control drug dosage as they are liquid pharmaceutical formulations.

Development and characterization of repellent formulations based on nanostructured hydrogels.

Diseases caused by insects could lead to epidemic scenarios in urban areas and insect repellents are a shield against a wide range of insects, but they need to be safe without compromising efficacy. Ethyl butylacetylaminopropionate (EB) is a synthetic mosquito repellent, which could be used in products for adults and children due to its low-allergenic potential. The aim of this study was to develop and characterize EB and Poloxamer 407 nanoemulsions regarding their droplets mean size, pH, rheological properties, cytotoxicity and in vitro permeation profile. The developed formulations (F1 with 12.5% of EB and F2 with 25% of EB) were compared with a commercial formulation containing 12.5% of EB. Droplets mean size was determined by DLS, and for both nanoemulsions they were around 200 nm; however, the commercial formulation presented a droplets mean size of 10 nm, which could contribute to its high permeation. F1 and F2 presented a gel-like behavior, however F2 presented lower viscosity due to the presence of more EB between the polymer chains preventing them to interact with each other. Also, F2 was less retained by the epidermis when compared to F1 probably due to its lower viscosity. For the cytotoxicity assay only F2, which presented the highest concentration of EB was tested, and it was not toxic to the cells. This result could be also extended to F1 which presented half the EB concentration. The present study demonstrated that EB and Poloxamer 407 nanoemulsions are promising as new insect-repellent formulations.

Therapeutic nanosystems for oral administration of insulin.

The treatment of Diabetes Mellitus (DM), a chronic disease, is primarily based upon administration of insulin forms to patients. Conventional subcutaneous administration is associated with a large number of complications, therefore, several new strategies have been developed. Amongst these strategies, oral insulin administration is much less invasive and, therefore, well tolerated. In recent years, various nanoformulations were developed for the oral administration of insulin, allowing more effective stabilization of the active pharmaceutical ingredient and modified for better absorption along the gastrointestinal tract. The development of different oral insulin nanoformulations in academic research as well as in patents, including the development of nanoparticles, liposomes, nanoemulsions and the use of cyclodextrins deserves special attention. The future of oral insulin nanoformulations is dependent on strategies utilizing simple technologies that stabilize the raw material, including inclusion within cyclodextrins or inclusion in low weight molecular mass polymers/ oligomers. All of the theories developed here provide a solid foundation upon which to develop new methods for the production of pharmaceutical peptide formulations. In addition, the effective search for existing nanometric formulations of insulin could provide economically viable therapeutic options that can consequently be produced on an industrial scale.

Development and characterization of a new oral dapsone nanoemulsion system: permeability and in silico bioavailability studies.

BACKGROUND: Dapsone is described as being active against Mycobacterium leprae, hence its role in the treatment of leprosy and related pathologies. Despite its therapeutic potential, the low solubility of dapsone in water results in low bioavailability and high microbial resistance. Nanoemulsions are pharmaceutical delivery systems derived from micellar solutions with a good capacity for improving absorption. The aim of this work was to develop and compare the permeability of a series of dapsone nanoemulsions in Caco-2 cell culture against that of effective permeability in the human body simulated using Gastroplus™ software. METHODS AND RESULTS: The release profiles of the dapsone nanoemulsions using different combinations of surfactants and cosolvent showed a higher dissolution rate in simulated gastric and enteric fluid than did the dispersed dapsone powder. The drug release kinetics were consistent with a Higuchi model. CONCLUSION: This comparison of dapsone permeability in Caco-2 cells with effective permeability in the human body simulated by Gastroplus showed a good correlation and indicates potential improvement in the biodisponibility of dapsone using this new system.