Abstract
The dissolution profiles of chlorpropamide (CPM) polymorphs, especially the metastable form II reported by Al-Saieq et al., were investigated kinetically in detail by a dispersed amount method and a stationary disk method in comparison with those of the stable form. Form II showed a dissolution phenomenon involving simultaneous phase change from metastable form to stable form during dissolution. The saturated concentrations of metastable form II and stable form A, Csm and Cso, the rate constant of the crystallization process Kr and the dissolution rate constant, K1, were calculated by the stationary disk method. By analyzing the values of Csm and Cso obtained at various temperatures, the transition temperature and heat of transition were determined. Further, the activation energies of crystallization and the dissolution process were also determined by Arrhenius plots of Kr and K1 obtained at various temperatures.
