It is often highly desirable to obtain bio-relevant results as such results increase the confidence and usefulness of the testing. In fact, one should always focus on achieving bio-relevant results as non-bio-relevant results are of limited use.
To obtain bio-relevant results, one should try to evaluate products using experimental conditions as close as possible to the conditions one would expect during the physiological testing and/or product use.
For evaluating in vivo drug dissolution, as conducted based on the bioavailability/bioequivalence studies, it is a common regulatory requirement that products be tested using a standard and common protocol. For example, the study protocol (physiological environment) remains the same for the evaluation of IR vs ER products and any release type in between. Therefore, if one wishes to achieve bio-relevant results, then one has to conduct in vitro testing using a common set of experimental conditions. These should be product-independent.
Conducting dissolution studies using product-dependent experimental conditions violates this principle, thus should not be considered bio-relevant. To obtain bio-relevant results, testing should be done using a common set of experimental conditions, which should also be product-independent.