FCS (DCF) - Artigos em Revistas Científicas Internacionais com Arbitragem Científica
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- Compressed matrix core tablet as a quick/slow dual-component delivery system containing ibuprofenPublication . Lopes, Carla Martins; Lobo, José M. Sousa; Pinto, João F.; Costa, Paulo C.The purpose of the present research was to produce a quick/slow biphasic delivery system for ibuprofen. A dualcomponent tablet made of a sustained release tableted core and an immediate release tableted coat was prepared by direct compression. Both the core and the coat contained a model drug (ibuprofen). The sustained release effect was achieved with a polymer (hydroxypropyl methylcellulose [HPMC] or ethylcellulose) to modulate the release of the drug. The in vitro drug release profile from these tablets showed the desired biphasic release behavior: the ibuprofen contained in the fast releasing component was dissolved within 2 minutes, whereas the drug in the core tablet was released at different times (≈16 or 924 hours), depending on the composition of the matrix tablet. Based on the release kinetic parameters calculated, it can be concluded that the HPMC core was suitable for providing a constant and controlled release (zero order) for a long period of time.
- Novel carriers for sunscreen formulationsPublication . Doktorovova, Slavomira; Marques, Cecília; Barbosa, Catarina; Lopes, Carla Martins; Souto, Eliana B.Sunscreens are cosmetic products for convenient and safe delivery of solar filters. These are used to prevent the skin damage caused by sunlight exposure. Due to photo-instability and potential adverse effects of some of these filters, novel application forms are demanded. Lipid based colloidal carriers commonly named as lipospheres provide the advantage of sufficient protection of the solar filters, their delivery to upper skin layer only, and controlled release. Being composed of biocompatible and biodegradable materials similar to those existing in the stratum corneum, they are generally well tolerated. This review gives an overview of novel approaches to sunscreen formulations.
- Effect of polymer viscosity on physicochemical properties and ocular tolerance of FB-loaded PLGA nanospheresPublication . Araújo, J.; Vega, E.; Lopes, Carla Martins; Egea, M.A.; Garcia, M.L.; Souto, Eliana B.Poly(lactide-co-glycolide) acid (PLGA) nanospheres incorporating flurbiprofen (FB) were produced by the solvent displacement technique, for ocular applications aiming to avoid/minimize inflammation induced by surgical trauma. In this work, a PLGA of low viscosity has been tested and the results obtained were compared with those previously reported by Vega et al. The physicochemical properties of the developed formulations were evaluated by measuring particle size, zeta potential and FB entrapment efficiency, showing no significant differences. Release studies demonstrated that the formulation produced with PLGA of higher viscosity revealed a slower drug release rate. Stability analysis, for a period of 75 days, was performed using three complementary methods: (i) turbidity experiments using a Turbiscan optical analyzer, (ii) particle size measurements, and (iii) zeta potential analysis. The results revealed long-term physicochemical stability suitability for ophthalmic use, being independent from the polymer viscosity. The ocular tolerance was assessed by an alternative in vitro method to animal experimentation, the HETCAM. For all developed formulations no ocular irritancy has been detected.
- A note on regulatory concerns and toxicity assessment in Lipid-Based Delivery Systems (LDS)Publication . Souto, Eliana B.; Martins-Lopes, Paula; Lopes, Carla Martins; Gaivão, Isabel; Silva, Amélia M.; Guedes-Pinto, HenriqueLipid-based Delivery Systems (LDS) has been the focus of potential strategies in drug delivery for several years. A great deal of work has been invested on how to exploit their biocompatible and biodegradable nature, in combination with their nanosize range in a profitable way in the field of nanomedicines. A number of drugs loaded in LDS have been already tested in vivo successfully. However, in vivo behaviour of nanosized materials differs from their bulk counterparts (and also change drug properties), mainly depending on the particular LDS physicochemical characteristics. These may have huge impact on the toxicity of the system, despite the physiological nature of the lipid materials. This note on the regulatory concerns and toxicity assessment in LDS suggests that current knowledge of public and scientific communities is lacking, requiring intensive research and policy measures to provide a deep understanding on toxicological risks.
- Nanoparticulate carriers (NPC) for oral pharmaceutics and nutraceuticsPublication . Lopes, Carla Martins; Martins-Lopes, P.; Souto, Eliana B.The introduction of nanoparticulate carriers (NPC) in the pharmaceutic and nutraceutic fields has changed the definitions of disease management and treatment, diagnosis, as well as the supply food chain in the agri-food sector. NPC composed of synthetic polymers, proteins or polysaccharides gather interesting properties to be used for oral administration of pharmaceutics and nutraceutics. Oral administration remains the most convenient way of delivering drugs (e.g. peptides, proteins and nucleic acids) since these suffer similar metabolic pathways as food supply. Recent advances in biotechnology have produced highly potent new molecules however with low oral bioavailability. A suitable and promising approach to overcome their sensitivity to chemical and enzymatic hydrolysis as well as the poor cellular uptake, would be their entrapment within suitable gastrointestinal (GI) resistant NPC. Increasing attention has been paid to the potential use of NPC for peptides, proteins, antioxidants (carotenoids, omega fatty acids, coenzyme Q10), vitamins, probiotics, for oral administration. This review focuses on the most important materials to produce NPC for oral administration, and the most recent achievements in the production techniques and bioactives successfully delivered by these means.
- 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.
- Nanobiotechnology approaches for targeted delivery of pharmaceutics and cosmetics ingredientsPublication . Andreani, T.; Doktorovova, S.; Lopes, Carla Martins; Souto, Eliana B.Nanobiotechnology refers to the ability to create and manipulate biological and bio-chemical materials, devices, and systems at atomic and molecular levels. Nano delivery systems hold great potential to overcome some of the obstacles in bio-pharmaceutical production, such as water soluble/insoluble pharmaceutical drugs and cosmetic ingredients, risks of toxicity, increasing bio-active efficacy, specificity, tolerability and its therapeutic index. Within nanoparticulate carriers, polymeric and lipid nanoparticles have risen to the forefront of bio-technology, having diverse applications in several fields of pharmaceuticals for oral, topical, ocular and intravenous administration, as well as in dermo-cosmetic products.
- Pharmaceutical approaches for optimizing oral anti-inflammatory delivery systemsPublication . Lopes, Carla Martins; Oliveira, R.; Silva, Ana CatarinaThe purpose of the present review is to compile the recent literature in the field of anti-inflammatory treatments, with special focus to the state-of-the-art on pharmaceutical approaches for optimizing oral administration. Attending to the drawbacks associated with the use of these types of drugs, the development of oral modulated release formulations is highly desirable in order to achieve improved therapeutic efficacy and patient compliance. Several technological systems and their advantages in modulated and targeted drug releases (gastroretention or colonic release) have been described: matrix systems, coated dosage forms, osmotic pressure based formulations, prodrugs, colloidal carriers, microparticles and other carriers. These new approaches seem to be promising and have been considered by pharmaceutical companies.
- Chronopharmaceutical delivery of anti-inflammatory drugsPublication . Barata, Pedro; Lopes, Carla MartinsThe human body follows 24 hours cycles called the circadian rhythm that affect many physiological and physiopathological processes. Chronotherapeutic diseases include asthma, cardiovascular diseases, cancer, rheumatoid arthritis and other algesia processes. Drugs behaviours in the human body are also strongly affected by circadian changes, especially in what concerns absorption and elimination. Anti-inflammatory drugs are excellent candidates to chronotherapeutical delivery. Chronotherapeutic products are able to synchronize drug delivery with circadian rhythms in order to enhance efficacy and reduce side effects. These products mainly offer pulsatile release that follow a sigmoid release profile with a combination of periods of lag time and periods of fast drug release. Many technologies, either single units or multiparticulate systems, have been suggested and some have been successfully marketed improving patients adherence and quality of life. This review aims to describe the circadian rhythms and their influences in therapeutics as well as the technologies that have been proposed to develop chronopharmaceutical dosage forms.