No abstract

No abstract

No abstract

Since the particle size distribution is a critical parameter of pharmaceutical excipients used for tablet manufacturing by direct compression, the mean particle size of sieved sorbitol powder was studied by near‐infrared diffuse reflectance spectroscopy (NIRDRS). The aim of this study was to investigate the effect of the particle size (reciprocally proportional to the bulk density) on the reflectance spectrum. The effects of the particle characteristics on the spectral changes were described on the basis of the Kubelka‐Munk theory taking the scattering into consideration. A smaller particle size fraction was associated with a lower spectral value, and at the characteristic wavelength of 1584 nm a linear relationship was established for the particle size range from 125 to 670 μm. The diffuse reflectance measurement was sensitive to the particle characteristics, which offers a fast, non‐destructive alternative test method that can be applied after detailed calibration.

No abstract

No abstract

The aim of the present study was to optimize the process of drug release. Factors which influence drug release were studied in detail and their effects were described numerically. The factors studied were as follows: the concentration of the pharmacon (salicylic acid); its particle size; its suspended, dissolved, solubilized, or molecular encapsulated state;, the composition of the vehicle; the quantities of the polar and apolar components; and the viscosity of the vehicle. Drug release studies were carried out with Hanson's vertical diffusion cell. The process was described quantitatively by the slope of the equation describing the time-course of the liberation, by the quantity of pharmacon liberated in 8 h and also by the optimization parameter determined on the basis of the 2 2 model of the factorial design method. Increase of the concentration of salicylic acid was found to be accompanied by an exponential rise in drug release, while the extent of liberation decreased linearly with increasing viscosity. The greatest increase in the optimization parameter was observed when the polarity of the vehicle was changed. The process of liberation consists of the following steps: dissolution of the pharmacon, diffusion of the dissolved molecules, and their distribution. The current data revealed that the distribution is the most important element and exerts the greatest influence on optimal drug release. Drug Dev. Res. 59:316-325, 2003.

No abstract