Sieve cuts as monodisperse powders in dissolution studies.

Dissolution profiles are calculated for sieve cuts of varying width based on a derived equation, which assumes diffusion rate-limited dissolution under sink conditions from spherical particles. It is shown that even the narrowest of sieve cuts may vary from cube root law expectations by as much as 3 percent, depending on the distribution of particles across the cut. Much smaller deviations from the cube root law occur when the weight distribution of diameters is constant across a sieve cut. It is concluded that when experimental data are treated on the assumption that sieve cuts act like monosized powders, errors generally will be acceptable except in cases of critical tests of dissolution rate theory. In those cases, more information about the powder distribution should be given.