Dissolution Theory, Experimentation and Modeling
A computer model has been developed here to simulate dissolution rates for a wide range of parameters. Particle size reduction with time was calculated via a single particle model developed by Higuchi-Hiestand. The other models are based on the Hixson-Crowell Cube root law. For experimental dissolution profiles of hydrocortisone, Lu, Frisella, and Johnson used a "shape factor" to allow for proper curve fit. The model presented in this paper assumes spherical particles and was validated with several lots of two different drugs. In addition the simulation was validated using the published data for hydrocortisone. The two drugs were chosen to represent a wide range of solubility in aqueous media, and a wide range of particle size distributions. Drug A, is only sparingly soluble in aqueous media and the particle sizes are relatively small (radii up to 64µm). Minoxidil, is about 20 times more soluble in aqueous media at 37°C and has much larger particle sizes (radii up to 640µm). This broad range of particle size and solubility was deemed sufficient to test the computer model limits.