Polymorphism of disopyramide

Two crystal forms of disopyramide have been characterized using X-ray diffraction, differential scanning calorimetry and infrared spectroscopy. The kinetics of the solid state transformation of Form I to Form II has been analysed using the Prout-Tompkins theory. An activation energy of 144 kJ mol-1 is calculated for the system. Dissolution and plasma concentrations show no significant differences in bioavailability between the two polymorphs.