galactomannan and scleroglucan

In this article, dynamic viscosity, surface tension, density, heat capacity and thermal conductivity, of a bronchial mucus simulant proposed by Zahm et al., Eur Respir J 1991; 4: 311-315 were experiementally determined. This simulant is mainly composed of a galactomannan gum and a scleroglucan. It was shown that thermophysical properties of synthetic mucus are dependant of scleroglucan concentrations. More importantly and for some scleroglucan concentrations, the syntetic mucus, exhibits, somehow, comparable thermophysical properties to real bronchial mucus. An insight on the microstructure of this simulant is proposed and the different properties enounced previously have been measured for various scleroglucan concentrations and over a certain range of operating temperatures. This synthetic mucus is found to mimic well the rheological behavior and the surface tension of real mucus for different pathologies. Density and thermal properties have been measured for the first time. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3025-3033, 2017.

Topics: Bronchi; Galactose; Glucans; Humans; Mannans; Mucus; Rheology; Surface Tension; Thermal Conductivity; Viscosity

Two galactomannans, Guar gum and Locust bean gum, have been used as matrices for tablets to study the release of model molecules. As a comparison, matrices obtained with another polysaccharide, Scleroglucan, have been tested. Despite the different conformations that the polymers assume in aqueous solution (flexible coils for Guar gum and Locust bean gum; triple helix for Scleroglucan), when prepared as tablets, they show (in distilled water and at 37 degrees C) very similar release profiles of guest molecules (i.e. theophylline, vitamin B12 and myoglobin) of different steric hindrance. Furthermore, the polymers were chemically crosslinked with glutaraldehyde to obtain a network suitable as a matrix for modified drug release. The delivery of the model molecules from the Guar gum and Locust bean gum gels, and from tablets prepared from the freeze-dried hydrogels of the three polymers was evaluated, and a comparison with the tablets prepared with the not-crosslinked polymers was carried out. Experimental data showed how the presence in the matrix of a well-defined network, by introducing a spacer among the macromolecular chains, always increased the rate of delivery of the tested molecules in comparison to the release profiles obtained when no crosslinker was present. Release data from the tablets were analyzed according to a mathematical model able to determine the relative importance of drug dissolution and drug diffusion on the overall release kinetics. Good agreement was found between the simulated and the experimental data.

Topics: Chemistry, Pharmaceutical; Cross-Linking Reagents; Delayed-Action Preparations; Diffusion; Drug Carriers; Drug Compounding; Galactans; Galactose; Glucans; Glutaral; Hydrogels; Kinetics; Mannans; Models, Chemical; Molecular Conformation; Molecular Structure; Myoglobin; Plant Gums; Solubility; Solvents; Tablets; Technology, Pharmaceutical; Theophylline; Vitamin B 12; Water