However, it is important to note that none of the currently suggested apparatuses and procedures can provide relevant and accurate dissolution results for any product.
The reason being NONE of the suggested and recommended apparatuses/procedures are qualified and/or validated for dissolution testing. Most, if not all, reported testing and results do not reflect the dissolution characteristics of the products but rather the presumed ones obtained by selecting product-dependent experimental conditions. See link for further details (Drug dissolution testing: Limitations of current practices and requirements).
As all of the above-mentioned guidances are dependent mostly on drug dissolution results, obviously, these documents cannot provide an intended and useful interpretation about the quality of pharmaceutical products in particular tablets and capsules.
A new or modified apparatus and/or procedure is required for appropriate uses/applications of the above-mentioned documents. A modified dissolution tester with a crescent-shaped spindle and a single set of experimental conditions may be used to address the flaws of the current practice providing improved product development and evaluation. Link for further details: A Simple and Unique Approach for Developing and Evaluating Products.