Browsing by Autor "Nilia de la Paz"

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In vitro release of dibucaine hydrochloride from chitosan semisolid vehicles: emulsion and hydrophilic gels
(2017) Nilia de la Paz; Dania Pérez; Mirna Fernández Cervera; Caridad García; Vivian Martínez; Antonio Nogueira; Oscar García
Context: Chitosan has received attention as a functional, sustainably renewable, nontoxic and biodegradable biopolymer for pharmaceutical applications. Aims: To evaluate the release of dibucaine hydrochloride from semisolid vehicles of oil/aqueous type emulsion and aqueous gels, stabilized by using chitosan (CH) or chitosan acetate (CHAc). Methods: Emulsions were developed by varying the emulsifying agent: polysorbate 80, CH or CHAc and by combining CH with polysorbate 80 or CHAc with polysorbate 80. The hydroxypropylmethyl cellulose F4M was added as a stabilizing agent in gel formulations. The release rates of model drug from semisolid vehicles were measured by using a dialysis sac. Drug release was also quantified by using a validated UV-VIS spectrophotometric method. Results: The pH values showed minimal changes for emulsion and gel formulations. The drug is a cationic salt, and it is not able to bind polymer cations by electrostatic repulsion. The rheological property of the vehicle type emulsion was adjusted to plastic and pseudo-plastic fluid to the gels. The drug release was independent of the viscosity of vehicles. Dibucaine release from both types of formulation was found to follow a square-root-of-time kinetic model, but a higher rate of release was obtained from gel formulations. Conclusions: It was shown that chitosan was adsorbed to the surface of polysorbate 80-coated droplets, and that the electrostatic attraction between the non-ionic surfactant and the drug retarded its release from a semisolid system. The multilayer emulsions showed more influence of the release of drug than CH or CHAc single layer emulsion.
Physical stability of emulsion and hydrophilic gels with chitosan and chitosan acetate
(2017) Nilia de la Paz; Dania Pérez; Mirna Fernández Cervera; Dulce M Soler; Yanet Rodríguez; Antonio Nogueira
Context: Chitosan has received great attention because it is a functional, biodegradable, renewable and non-toxic biopolymer with multiple pharmaceutical applications, including stabilizing agent. Aims: To evaluate the physical stability of emulsified bases and hydrophilic gels containing chitosan or chitosan acetate as stabilizing agents. Methods: Stability of shelf-life formulations at room temperature and in refrigeration was evaluated over a period of 60 days and by thermal stress testing and centrifugal destabilization. The organoleptic characteristics, pH, conductivity and flow behavior were evaluated, the latter through the analysis of the rheograms, the determination of rheological parameters (consistency index, apparent viscosity, creep value and flow index), as well as their comparison statistics. The possible correlations between these parameters and the concentration of the biopolymers were also evaluated. Results: The bases elaborated with chitosan or its soluble derivative showed adequate physical stability during the study time. The effect of the storage temperature, as well as the type and concentration of the stabilizing agent used was evidenced. Emulsifier combinations provided less stability. A linear correlation between the rheological parameters and the biopolymer concentration was evidenced. Conclusions: Chitosan and chitosan acetate can be used as emulsifying agents in semi-solid and gelling bases in hydrophilic gels, due to the electrostatic stabilization and the viscosity they contribute to the system in relation to its concentration.
Stability of spray-dried chitosan salts derived from lobster chitin as a raw material
(Facultad de Farmacia, 2015) Nilia de la Paz; Caridad García; Mirna Fernández Cervera; Lisandra de la Caridad Núñez García; Vivian Martínez; Orestes Darío López Hernández; Antonio Nogueira
Objetivos. Desarrollar y validar un mtodo para la determinacin del grado de desacetilacin molar del acetato de quitosana y lactato de quitosana, y realizar el estudio de estabilidad de ambas sales.
Validación de métodos analíticos aplicables al control de calidad y estudio de estabilidad de las gotas nasales de efedrina
(2014) Niurka Benítez; Juan Manuel Cordoví; Mirna Fernández Cervera; Reynerio Zamora; Nilia de la Paz; Pavel Cabrera
Aims: The purpose of this study was to validate three analytical methods for quality control and stability study of nasal drops ephedrine hydrochloride.Materials and methods: A liquid chromatographic technique was developed for the quantification of ephedrine hydrochloride and two volumetric techniques for quantification of benzalkonium chloride and edetate disodium, preservatives in the formulation. The evaluated parameters were consistent with internationally established quantitative techniques such as specificity, linearity, accuracy, precision, robustness and limits of detection and quantification.Results: It was demonstrated that the chromatographic method was linear, with a detection limit of 2.62 μg/mL and 5.56 μg/mL as LOQ, selective, accurate, precise and robust. The volumetric method for the benzalkonium chloride was linear, with a detection limit of 0.60 μg/mL and 2.24 μg/mL as the limit of quantification, specific, accurate, precise and robust. The results of the performance evaluation of volumetric method for disodium edetate demonstrated their precision, accuracy and specificity.Conclusions: The chromatographic method for the determination of the active as well as volumetric methods for the quantification of preservatives in the formulation met all the parameters evaluated in the validation, being useful for quality control and stability study.