Time and temperature dependence of disintegration and correlation between dissolution and disintegration rate constants.

Commercial prednisone tablets were subjected to dissolution tests by USP basket and paddle methods. It was found experimentally that disintegration adheres to an exponential decay law: ln(W/Wo) = -d(t-ti), where W is the nondisintegrated weight, d is a disintegration constant, t is time, and ti is a lag time. Dissolution has been reported to adhere to a similar law, where the dissolution constant K, follows a pseudo-Arrhenius relationship with changing temperature. Within a certain temperature range, this relationship also exists for the disintegration rate constant, d. A correlation exists in these tablets between K and d. The shaft length in the dissolution apparatus plays a part in the disintegration (and hence dissolution) rate and, therefore, is an important apparatus parameter affecting reproducibility.