Pharmaceutical compounds, diffusion through

SCF such as supercritical Q as been widely used in the pharmaceutical Leld owing to its relatively low critical point (304 K and 7.38 Mbar), which can be easily achieved, and the Luid s ability to dissolve most pharmaceutical compounds. One application of the SCF process is the rapid expansior of supercritical solutions (RESS) [48], During RESS process, the SCF is diffused through a bed of solid solute (i.e., extractor), as shown schematically in Figure 18.7. As the Luid diffuses through the bed, the solid solute dissolves in it. The Luid solution is then depressurized in a separate chamber... 

Statistics. The results of 367 flow-through diffusion cell tests are presented. The standard deviation of the flux divided by the mean flux or the coefficient of variation between different flow-through cell types, pharmaceutical compounds, and different technicians are compared (4). The coefficients of variation are compared by analysis of variance (5) using the RSI (BBN Research Systems, Cambridge, MA) research statistics software. 

Materials used to coat pharmaceutical products are primarily based on acrylic and cellulosic polymers and the aqueous solubility characteristics of these compounds generally dictate their uses. Sustained release coatings are water-insoluble or swellable films through which the medicament slowly diffuses. Drug products coated with these polymers are administered less frequently and the high peak plasma concentrations... 

Silicone elastomers were first used as the basis for controlled drug delivery systems in 1962, when Folkman and Long discovered that low molecular weight compounds could diffuse, at a controlled rate, through the walls of silicone tubing [18-20]. That observation led to the development of several clinical products for controlled delivery of pharmaceutical agents. Most notably, the Population Council developed tubes of SILASTIC (in this case. 

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