IDR versus solubility

“Ideally” the intrinsic dissolution rate (IDR) reflects the solubility of the compound at a defined pH value, i.e. if the solubility increases with a factor 2, the same will happen to the intrinsic dissolution rate. Thus, if the solubility is known, it is usually sufficient to measure the IDR at one pH value. This is quite time saving, as a solubility measurement is very quick/cheap compared to an IDR measurement. The solubility results combined with information about the particle sizes can be used in estimation of the maximal absorbable dose in vivo.