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Fangueiro J.F.,Fernando Pessoa University | Parra A.,University of Barcelona | Silva A.M.,University of Tras os Montes e Alto Douro | Silva A.M.,Center for Research and Technology of Agro Environmental and Biological science | And 5 more authors.
International Journal of Pharmaceutics | Year: 2014

Epigallocatechin gallate (EGCG) is a green tea catechin with potential health benefits, such as anti-oxidant, anti-carcinogenic and anti-inflammatory effects. In general, EGCG is highly susceptible to degradation, therefore presenting stability problems. The present paper was focused on the study of EGCG stability in HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) medium regarding the pH dependency, storage temperature and in the presence of ascorbic acid a reducing agent. The evaluation of EGCG in HEPES buffer has demonstrated that this molecule is not able of maintaining its physicochemical properties and potential beneficial effects, since it is partially or completely degraded, depending on the EGCG concentration. The storage temperature of EGCG most suitable to maintain its structure was shown to be the lower values (4 or -20 °C). The pH 3.5 was able to provide greater stability than pH 7.4. However, the presence of a reducing agent (i.e., ascorbic acid) was shown to provide greater protection against degradation of EGCG. A validation method based on RP-HPLC with UV-vis detection was carried out for two media: water and a biocompatible physiological medium composed of Transcutol®P, ethanol and ascorbic acid. The quantification of EGCG for purposes, using pure EGCG, requires a validated HPLC method which could be possible to apply in pharmacokinetic and pharmacodynamics studies. © 2014 Published by Elsevier B.V.


Fangueiro J.F.,Fernando Pessoa University | Andreani T.,Fernando Pessoa University | Andreani T.,Center for Research and Technology of Agro Environmental and Biological science | Andreani T.,University of Tras os Montes e Alto Douro | And 5 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2012

Solid lipid nanoparticles (SLNs) produced from multiple emulsions technology theoretically enclose an inner aqueous compartment suitable for hydrophilic biomolecules. This paper reports a 33 full factorial design study to optimize SLNs formulations for hydrophilic biomolecules. The concentrations of solid lipid, lipophilic and hydrophilic emulsifiers were set as the 3 independent variables. Mean particle size (Z-Ave), polydispersity index (PI) and zeta potential (ZP) were set as the dependent variables. The selected optimized parameters were set as 1.0wt% of solid lipid, 0.25wt% of lipophilic emulsifier and 1.5wt% of hydrophilic emulsifier. The coating of SLNs with sodium alginate was found to improve the ZP of the lipid particles and these results suggest that the ideal concentration was 0.75wt%. The influence of low pH (i.e., about 2-3) in the inner aqueous phase was stronger than higher pH values, contributing for the production of larger droplet sizes. Nevertheless, these systems can be useful for the incorporation of biomolecules requiring a pH ranging between 4 and 10. SLNs based on multiple emulsions technology were found to be a promising approach for the incorporation of several hydrophilic drugs, such as proteins and peptides. © 2012 Elsevier B.V.


De Souza A.L.R.,Paulista University | De Souza A.L.R.,University of Tras os Montes e Alto Douro | Andreani T.,University of Tras os Montes e Alto Douro | Andreani T.,Center for Research and Technology of Agro Environmental and Biological science | And 10 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2012

Praziquantel (PZQ) is the drug of choice for oral treatment of schistosomiasis and other fluke infections that affect humans. Its low oral bioavailability demands the development of innovative strategies to overcome the first pass metabolism. In this article, solid lipid nanoparticles loaded with PZQ (PZQ-SLN) were prepared by a modified oil-in-water microemulsion method selecting stearic acid as lipid phase after solubility screening studies. The mean particle size (Z-Ave) and zeta potential (ZP) were 500 nm and -34.0 mV, respectively. Morphology and shape of PZQ-SLN were analysed by scanning electron microscopy revealing the presence of spherical particles with smooth surface. Differential scanning calorimetry suggested that SLN comprised a less ordered arrangement of crystals and the drug was molecularly dispersed in the lipid matrix. No supercooled melts were detected. The entrapment efficiency (EE) and loading capacity of PZQ, determined by high performance liquid chromatography, were 99.06 ± 0.3 and 17.48 ± 0.05, respectively. Effective incorporation of PZQ into the particles was confirmed by small angle X-ray scattering revealing the presence of a lipid lamellar structure. Stability parameters of PZQ-SLN stored at room temperature (25 °C) and at 4 °C were checked by analysing Z-Ave, ZP and the EE for a period of 60 days. Results showed a relatively long-term physical stability after storage at 4 °C, without drug expulsion. © 2011 Akadémiai Kiadó, Budapest, Hungary.


Fangueiro J.F.,Fernando Pessoa University | Andreani T.,Fernando Pessoa University | Andreani T.,Center for Research and Technology of Agro Environmental and Biological science | Andreani T.,University of Tras os Montes e Alto Douro | And 7 more authors.
International Journal of Pharmaceutics | Year: 2014

In the present study we have developed lipid nanoparticle (LN) dispersions based on a multiple emulsion technique for encapsulation of hydrophilic drugs or/and proteins by a full factorial design. In order to increase ocular retention time and mucoadhesion by electrostatic attraction, a cationic lipid, namely cetyltrimethylammonium bromide (CTAB), was added in the lipid matrix of the optimal LN dispersion obtained from the factorial design. There are a limited number of studies reporting the ideal concentration of cationic agents in LN for drug delivery. This paper suggests that the choice of the concentration of a cationic agent is critical when formulating a safe and stable LN. CTAB was included in the lipid matrix of LN, testing four different concentrations (0.25%, 0.5%, 0.75%, or 1.0%wt) and how composition affects LN behavior regarding physical and chemical parameters, lipid crystallization and polymorphism, and stability of dispersion during storage. In order to develop a safe and compatible system for ocular delivery, CTAB-LN dispersions were exposed to Human retinoblastoma cell line Y-79. The toxicity testing of the CTAB-LN dispersions was a fundamental tool to find the best CTAB concentration for development of these cationic LN, which was found to be 0.5 wt% of CTAB. © 2013 Elsevier B.V. All rights reserved.


Andreani T.,University of Tras os Montes e Alto Douro | Andreani T.,Center for Research and Technology of Agro Environmental and Biological science | Fangueiro J.F.,Center for Research and Technology of Agro Environmental and Biological science | Fangueiro J.F.,University of Coimbra | And 5 more authors.
Current Pharmaceutical Design | Year: 2015

Hydrophilic polymers are the most common group of polymers used in the preparation of modifiedrelease drug delivery systems. This is due to their versatility, low cost, high production yield, as well as easy manufacturing and adequate in vitro/in vivo correlation. In normal physiological conditions, the matrix controls the release of the loaded drug over time through a process of diffusion and/or erosion of the matrix, depending on its physicochemical composition. This is particularly relevant when describing the pharmacokinetic profile of nanosized drug delivery systems (nanoparticles). The use of mathematical models became an important tool to characterize the pharmacokinetics of drugs loaded in nanoparticles to improve the drug bioavailability and to establish bioequivalence. Therefore, the drug release profile can be predicted by a minimum number of experimental studies, since the mathematical equations reveal the dissolution rate of the drug loaded in the hydrophilic matrix. The present paper discusses the use of mathematical models when developing modified-release drug delivery systems of nanometer size composed of hydrophilic polymers. © 2015 Bentham Science Publishers

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