ABSTRACT
The rate with which a drug substance dissolves either from neat drug or from a dosage form is of great importance because it often governs the biopharmaceutical profiles of the drug.
12.1. THE NOYES-WHITNEY EQUATION The equation developed by Noyes and Whitney in 1887, states that (Fig. 12.1), when a substance (with solubility S) dissolves from a planar surface of surface A, then its dissolution rate, -dm/dt (where m is mass and t is time), is given by
Fig. 12.1 Wood's apparatus.
