Dissolution modeling: factors affecting the dissolution rates of polydisperse powders.
The dissolution rates of two lots of hydrocortisone (fine and coarse) were simulated using a computer program based on a Noyes-Whitney-type equation. Derivations of the equation were made to compare the accuracy of simulations using spherical and cylindrical particle geometry, with and without a time-dependent diffusion layer thickness. To approximate better the shape of the hydrocortisone particles, a shape factor was used to relate cylindrical length to radius. The most accurate simulations were obtained by assuming cylindrical geometry with and without a time-dependent diffusion layer thickness for the fine and coarse hydrocortisone, respectively. The program was also modified to simulate initial particle size distributions based on the log normal probability density function.
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Central Research Division, Pfizer Inc., Groton, Connecticut 06340.
Frisella
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Johnson
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D004058:Diffusion; D006854:Hydrocortisone / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D010316:Particle Size; D011208:Powders; D012984:Software; D012995:Solubility
D011208:Powders; D006854:Hydrocortisone