Browsing by Author "González-Mira, E."
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- Current progresses on nanodelivery systems for the treatment of neuropsychiatric diseases: Alzheimer’s and SchizophreniaPublication . Silva, Ana Catarina; González-Mira, E.; Lobo, J.M. Sousa; Amaral, M.H.Currently Alzheimer's disease and schizophrenia are both well-established neuropsychiatric diseases. Nonetheless, the treatment of these disorders is not unanimous and fully effective. As a consequence, several approaches have been studied to improve patient's conditions. In this context, the development of new drug nanodelivery systems to increase drug bioavailability and reduce adverse effects has been claimed as a good option. Among these systems we focus on the ones that seem to be most promising, such as lipidbased systems (e.g. liposomes, nanoemulsions and lipid nanoparticles), drug nanocrystals, polymeric nanoparticles and micelles. Moreover, the application of these systems by means of alternative administration routes is also discussed. Regardless of the satisfactory results and the associated progresses that have been done in the last years, more studies are required to quickly licence the application of drug nanodelivery systems in human medicines.
- Preparation, characterization and biocompatibility studies on risperidone-loaded solid lipid nanoparticles (SLN): High pressure homogenization versus ultrasoundPublication . Silva, Ana Catarina; González-Mira, E.; García, M.L.; Egea, M.A.; Fonseca, J.; Silva, R.; Santos, D.; Souto, Eliana B.; Ferreira, D.The suitability of solid lipid nanoparticles (SLN) for the encapsulation of risperidone (RISP), an antipsychotic lipophilic drug, was assessed for oral administration. The hot high pressure homogenization (HPH) and the ultrasound (US) technique were used as production methods for SLN. All the studies on the SLN formulations were done in parallel, in order to compare the results and conclude about the advantages and limitations of both techniques. The particle sizes were in the nanometer range for all prepared SLN formulations and the zeta potential absolute values were high, predicting good long-term stability. Optical analyses demonstrated the achievement of stable colloidal dispersions. Physicochemical characterization of dispersions and bulk lipids, performed by differential scanning calorimetry (DSC) and X-ray assays, support prediction of occurrence of drug incorporation in the SLN and good long term stability of the systems. The toxicity of SLN with Caco-2 cells and the existence of contaminations derived from the production equipments were assessed by the (4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) assay. The results showed 90% of cell viability after SLN exposure, with no significant differences within all prepared formulations (p > 0.05). From this study, we conclude that SLN can be considered as efficient carriers for RISP encapsulation. Moreover, HPH and US revealed to be both effective methods for SLN production.
- Solid lipid nanoparticles (SLN) - based hydrogels as potential carriers for oral transmucosal delivery of Risperidone: preparation and characterization studiesPublication . Silva, Ana Catarina; Amaral, M.H.; González-Mira, E.; Santos, D.; Ferreira, D.Two different solid lipid nanoparticles (SLN)-based hydrogels (HGs) formulations were developed as potential mucoadhesive systems for risperidone (RISP) oral transmucosal delivery. The suitability of the prepared semi-solid formulations for application on oral mucosa was assessed by means of rheological and textural analysis, during 30 days. Plastic flows with thixotropy and high adhesiveness were obtained for all the tested systems, which predict their success for the oral transmucosal application proposed. The SLN remained within the colloidal range after HGs preparation. However, after 30 days of storage, a particle size increase was detected in one type of the HGs formulations. In vitro drug release studies revealed a more pronounced RISP release after SLN hydrogel entrapment, when compared to the dispersions alone. In addition, a pH-dependent release was observed as well. The predicted in vivo RISP release mechanism was Fickian diffusion alone or combined with erosion.