Síntesis y caracterización de polímeros de ciclodextrina. Aplicación a la liberación de fármacos

Cyclodextrins (CD) are cyclic oligosaccharides which have been widely employed for pharmaceutical applications. CD based hydrogels have been synthesized by the crosslinking reaction with epichlorohydrin using αCD, ßCD, γCD, and 50:50 mixtures of α/ßCD and ß/γCD, at different synthesis temperatures. These gels have been characterized by measuring their swelling capacity, mechanical behavior, thermal properties and pore size distribution. The hydrogels synthesized at higher temperatures present a higher swelling capacity, due to the self-polymerization of epichlorohydrin, yielding a more expanded reticular structure with pores of higher diameter. Mechanical assays show that a lower synthesis temperature leads to stronger and harder polymers, according with a lower swelling capacity. Polymers containing different CD types and synthesized at the same temperature present similar reticular structures. In order to investigate the sorption capacity of these hydrogels toward different solutes, five model molecules have been selected: phenol, 3-nitrophenol, 4-nitrophenol, 1-naphthol, and the antiinflamatory drug diflunisal. The amounts sorbed have been related to the different affinities of CDs to the solutes. Drug delivery of two antiinflammatory (naproxen and nabumetone) and two antifungal drugs (naftifine and terbinafine) from ßCD polymer discs has been investigated. Drug release kinetics were carried out at physiological conditions of pH and temperature, and kinetic and diffusion constants were calculated. The drug release followed a simple Fickian diffusion mechanism for all the model drugs. Also, diffusion coefficients were calculated according to the simplified Higuchi model. Naproxen was also used to perform release assays from polymers containing different CDs. The βCD polymer showed the highest amount of drug loaded and the lowest one corresponds to the polymer containing αCD, in agreement with the affinities for naproxen of the corresponding cyclodextrins. It can be inferred that a simple Fickian diffusion mechanism occurs, except for the mixed polymers at pH 1.2 (anomalous transport) and in the case αCDP at pH 7.0 (burst phenomenon). Furthermore, the diffusion and relaxation contributions have been determined for the mixed polymers in order to achieve progress in the design of new polymer matrices according to the structure of the selected drugs

In-vitro release from reverse poloxamine/α-cyclodextrin matrices. Modelling and comparison of dissolution profiles

ABSTRACT: Gels obtained by complexation of octablock star PEO/PPO copolymers (Tetronic 90R4) with α-CD were evaluated as matrices for drug release. Both molecules are biocompatible so they can be potentially applied to drug delivery systems. Two different types of matrices of Tetronic 90R4 and α-CD were evaluated: gels and tablets. These gels are capable to gelifying in-situ and show sustained erosion kinetics in aqueous media. Tablets were prepared by freeze drying and comprising the gels. Using these two different matrices the release of two model molecules, L-Tryptophan (Trp), and a protein, bovine serum albumin (BSA), was evaluated. The release profiles of these molecules from gels and tablets prove that they are suitable for sustained delivery. Mathematical models were applied to the release curves from tablets in order to elucidate the drug delivery mechanism. Good correlations were found for the fittings of the release curves to different equations. The results point that the release of Trp from different tablets is always governed by Fickian diffusion while the release of BSA is governed by a combination of diffusion and tablet erosion

COVID-19 y medios digitales de educomunicación

En este trabajo analizamos el uso de los medios digitales de educomunicación (MDE) por docentes de educación superior. Los MDE refieren al uso de tecnologías de información y comunicación (TIC) para enriquecer las actividades educativas. Aquí destacamos los efectos de la pandemia en el uso de los MDE, según los resultados de entrevistas realizadas en línea a diez docentes de dos facultades, Ingeniería y Filosofía y Letras, de dos universidades, la Universidad Autónoma de Chihuahua (UACH) y la Universidad Nacional Autónoma de México (UNAM)

Propuesta metodológica para analizar la educomunicación digital en la educación superior

Este artículo describe un diseño metodológico mixto, propuesto para analizar el uso de los medios digitales de educomunicación (MDE) en la educación superior de México. Tal diseño busca proveer elementos para analizar cómo los docentes perciben el uso de la tecnología en el aula, al sugerir el empleo de dos etapas de recolección de datos: primero, empleando una encuesta con preguntas de selección múltiple, jerarquización y ponderación, así como de escala de tipo Likert y diferencial semántico; la segunda etapa implica entrevistas a profundidad con los docentes seleccionados según su tiempo trabajando como educadores y el que llevan usando los MDE. En la instrumentalización de esta propuesta metodológica se verificaría la dependencia y aceptación tecnológica del docente, además se podrá llegar a una serie de generalidades en el proceso de enseñanza en ramas del conocimiento específico y características personales de los docentes; también se podrá ubicar cuáles MDE coinciden con el modelo de aceptación tecnológica y cuáles se alejan más de sus postulados, así como indagar sobre las percepciones de los docentes respecto a la eficacia y gusto de los MDE al momento de impartir sus clases

In-vitro release from reverse poloxamine/α-cyclodextrin matrices. Modelling and comparison of dissolution profiles

ABSTRACT: Gels obtained by complexation of octablock star PEO/PPO copolymers (Tetronic 90R4) with α-CD were evaluated as matrices for drug release. Both molecules are biocompatible so they can be potentially applied to drug delivery systems. Two different types of matrices of Tetronic 90R4 and α-CD were evaluated: gels and tablets. These gels are capable to gelifying in-situ and show sustained erosion kinetics in aqueous media. Tablets were prepared by freeze drying and comprising the gels. Using these two different matrices the release of two model molecules, L-Tryptophan (Trp), and a protein, bovine serum albumin (BSA), was evaluated. The release profiles of these molecules from gels and tablets prove that they are suitable for sustained delivery. Mathematical models were applied to the release curves from tablets in order to elucidate the drug delivery mechanism. Good correlations were found for the fittings of the release curves to different equations. The results point that the release of Trp from different tablets is always governed by Fickian diffusion while the release of BSA is governed by a combination of diffusion and tablet erosion