The purpose of any analytical procedure, including dissolution testing, is to determine an unknown property of a test substance/matrix. However, in the case of current practices of drug dissolution testing, this is not the situation. Here, one seeks experimental conditions to obtain desired or expected release characteristics of the products. These are then described, incorrectly, as procedures for method development, obtaining discriminatory tests and/or bio-relevant tests, etc. Furthermore, it is important to note that for all these practices, a test product itself is used as its own reference. Therefore, one can never know the actual or real dissolution characteristics of any product.
For appropriate dissolution testing, the dissolution method (apparatus with associated experimental conditions) must remain constant, i.e., these should not change from product to product. For example, a method must remain the same if one would like to test or compare characteristics of an IR vs ER product. For further discussion, the linked article may be useful.
