Solubility screening studies provide information on the best solvent media for a given crystallization process. Solubility data is also relevant during pre-formulation evaluations of APIs. Solubility curves and metastable zone width in a given solvent are determined with small amount of API and in a short period of time.
An additional characterization of bulk drug substances and excipients is the measurement of intrinsic dissolution rates. Its determination can be in some cases important since bioavailability of an API is influenced by the dissolution rate. Furthermore, intrinsic dissolution tests are a way to prove chemical purity, batch-to-batch consistency and sameness after changes in production.