Extruder scale-up assessment in the process of extrusion-spheronization: comparison of radial and axial systems by a design of experiments approach.

Scaling-up the extrusion-spheronization process involves the separate scale-up of each of the five process steps: dry mixing, granulation, extrusion, spheronization, and drying. The aim of the study was to compare two screw extrusion systems regarding their suitability for scaling-up. Two drug substances of high- and low-solubility in water were retained at different concentrations as formulation variables.

The effects of relative humidity and super-disintegrant concentrations on the mechanical properties of pharmaceutical compacts.

The influence of the composition and the relative humidity on the properties of pharmaceutical compacts prepared from mixtures of three excipients and three super-disintegrants was evaluated. Various amounts of super-disintegrant and different conditions of relative humidity during the storage were used to study mechanistically the disintegration process and to connect it to compact's mechanical properties. Three point single beam test was used to measure tensile strength and Young's modulus of compacts containing various amount of disintegrant and stored under various relative humidity.

Cross-linking of chitosan and chitosan/poly(ethylene oxide) beads: a theoretical treatment.

The major aim of this study was to get deeper insight into the process of polymer cross-linking and the resulting structure of beads based on chitosan (CS) or chitosan/poly(ethylene oxide) (CS/PEO) semi-interpenetrating networks (semi-IPNs) as new carrier materials for oral drug delivery. Spherical hydrogels were prepared by a dropping method. The uptake kinetics of the cross-linking agent glyoxal into the beads were monitored and quantitatively described using Fick's second law of diffusion.

Application of percolation model to the tensile strength and the reduced modulus of elasticity of three compacted pharmaceutical excipients.

Percolation theory has been applied to several mechanical properties of pharmaceutical tablets. This power law describes the change of tablet's properties with the relative density. It defines critical tablet densities from which the mechanical properties start to change.

Quantitative measurements of localized density variations in cylindrical tablets using X-ray microtomography.

Direct compaction is a complex process that results in a density distribution inside the tablets which is often heterogeneous. Therefore, the density variations may affect the compact properties. A quantitative analysis of this phenomenon is still lacking.

Compaction of crystallographic forms of pharmaceutical granular lactoses. II. Compacts mechanical properties.

It is well known that the choice of the crystal form affects the physicochemical properties such as compaction behaviour. In this work, the mechanical properties of compacts obtained from compaction of lactoses by using a micropress prototype are calculated. Tensile strength, Young's modulus, toughness and Brinell hardness were measured and used to compare the various crystalline forms: alpha-lactose monohydrate (LalphaM), anhydrous beta-lactose (LbetaA), anhydrous alpha-lactose (LalphaA) and partly amorphous lactose (FF).

Complex dispersions of multilamellar vesicles: a promising new carrier for controlled release and protection of encapsulated molecules.

Multilamellar vesicles called Spherulites have recently been discovered and are being developed for encapsulation applications. In this study, we present new systems of Spherulites called complex dispersions. These are prepared by dispersing Spherulites within an oily medium, and then emulsifying this oily dispersion of Spherulites within an aqueous solvent.