Biomedical subjects

Mariagrazia Marucci

Publications and source records attributed to Mariagrazia Marucci.

3 recordsLinked to original sources

PubMed2006

Evaluation of osmotic effects on coated pellets using a mechanistic model.

The aim of this study was to develop a simple experimental methodology and to develop a mechanistic model to characterize the release mechanism from pellets developing cracks during the release process with special focus on osmotic effects. The release of remoxipride from pellets coated with an ethyl cellulose film was chosen as a case study. Dose release experiments at different bulk osmotic pressures revealed that the release process was mainly osmotically driven. The model was used to calculate the solvent permeability of the coating, 1.1 x 10(-10)m(2)h(-1)MPa(-1). The model was validated by release experiments using similar pellets having different coating thicknesses. The effective diffusion coefficient of remoxipride in the coating was also calculated and found to be 1.7 x 10(-10)m(2)h(-1). A series of experiments was performed in which the osmotic pressure of the receiving solution was changed during the experiment. From the results of these experiments, the area of the cracks in the film, formed by the hydrostatic pressure built up inside the pellets, was estimated to be 3.5 x 10(-5)m(2)/m(2) coating. It could also be deduced that the solvent permeability of the coating film was affected by swelling in the same way at different osmotic pressures.

Algorithms↗

PubMed2006

Electronic speckle pattern interferometry: a novel non-invasive tool for studying drug transport rate through free films.

In this work, Electronic Speckle Pattern Interferometry (ESPI) is presented as a non-invasive tool to study drug transport in controlled release systems. ESPI is shown to be a feasible tool to measure drug film permeability via comparison with an ordinary diaphragm cell. A specially designed cuvette was used in the release study: the polymeric film separated the donor and the receiving chambers of the cuvette to create a diffusion cell with no mixing in the two chambers. Thus, the cuvette mimicked a coated system immersed in a stagnant bulk liquid. Concentration profile data were obtained for the two compartments. Using these data, it was possible to visually discriminate between a film subject only to diffusion and a film subject to diffusion as well as osmotic effects. Moreover, using the concentration profile data collected at different time intervals, it was possible to follow the film properties in terms of drug permeability, thus studying how drug permeability depended on drug concentration. Compared to other measuring techniques, ESPI offers the advantages that no invasive measurements are needed, and that no sampling and calibration are required. Furthermore, the permeability can be measured with no influence of mass transfer in the boundary layers.

Benzyl Alcohols↗

PubMedDate not supplied

Polygalacturonic acid/endo-polygalacturonase system: a kinetic study in batch reactors.

The enzymatic depolymerization of the pectic substance polygalacturonic acid (PGA) is studied in batch reactor. The number-average molecular weight of native substrate is estimated, using a simple and quick technique, to be approximately 11.1 kDa, the polymeric chains consisting on average of 63 galacturonic acid units. The effect of enzyme concentration was studied varying biocatalyst loading from 6 to 242 mg/L. The experiments were repeated at substrate concentrations ranging from 0.5 to 5 g/L. Data obtained at both short reaction time (20 min) and prolonged enzyme action (up to 350 min) are correlated using different kinetic equations, and the parameter values are discussed.

Bioreactors↗