1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

Early pharmaceutical profiling to predict oral drug absorption: current status and unmet needs

The ability of sodium taurocholate to increase the initial dissolution rate of five steroids was studied in terms of effects on solubility, wetting, and diffusion coefficient For all compounds, wetting effects predominated over solubilization effects at bile salt concentrations representative of the fasted state For hydrocortisone, triamcinolone, betamethasone, and dexamethasone, this trend also continued at the higher bile salt concentrations typical of the fed state Bile salts solubilized these compounds by a factor of two or less, and diffusivity changes were negligible at bile salt concentrations up to 30 mM For the more lipophilic danazol, the wetting effects were small and of importance only at premicellar levels of bile salt At higher concentrations, the increase in solubility was the predominant factor Incorporation into micelles appeared to decrease the diffusivity slightly, but this was important only at bile salts concentrations of 15 mM or higher In conclusion, it appears that even within a series of structurally related compounds the mechanism by which bile salts mediate increases in dissolution rate can differ considerably

Solubilization and wetting effects of bile salts on the dissolution of steroids.

Melt extrusion – an alternative method for enhancing the dissolution rate of 17β-estradiol hemihydrate

The dissolution rates of several drugs may be increased by incorporation into solid polyethylene glycols1. These dispersions are usually manufactured by heating a physical mixture of the drug and polymer to the fluid state and subsequently cooling to room temperature.The physical structure of both the drug and the polyethylene glycol will be discussed, as these factors may affect the rate of drug release from the dispersions2,3. The solid state properties of both components have traditionally been studied by X-ray diffraction and/or by differential scanning calorimetry (DSC). The latter technique has facilitated the use of phase diagrams in the investigation of the melting properties of the dispersions, these usually indicating the presence of eutectics, monotectics, solid solutions or glasses. The application of a further technique, dielectric spectroscopy, in the study of molten and solid dispersions will be described.The mechanisms by which drug dissolution rate may be enhanced will be describe...

Andreas Ohm

Papers

Correlation between wettability and dissolution rate of pharmaceutical powders