Dissolution of nonspherical powders.

To elucidate the effect of particle shape on the dissolution profile of a powder, an equation was derived for the dissolution of powders whose particles are rectangular parallelepipeds and log-normally distributed by introducing three-dimensional parameters instead of diameter in the Brooke equation for the spherical powder dissolution. By using some hypothetical values for constants in the equation, it is shown that the smallest side length, alphao does greatly affect the dissolution profile but that the other two side lengths, and betaalphao, do not, even with rather large values of alpha and beta. Nonisotropic dissolution also is discussed.