This chapter appears quite popular and is often cited as a source for help and information concerning dissolution methods development and validation. However, if one evaluates it, even superficially, one should immediately realize that the chapter is based on invalid assumptions and false science. For example:
The chapter is meant to be helpful and useful in developing and validating a dissolution method. However, the problem is that for such a purpose a fundamental requirement is that one requires a reference product with known dissolution characteristics established independently. In this case, one requires a reference product, which should be approved for human use as the method is to be used for such a purpose, with known dissolution characteristics. The (dissolution) method development means that, using valid scientific principles and testers, the developed and validated method would be able to provide an expected answer for the reference product. This developed and validated method will then be used for evaluating the test products. As, at present, a reference product with known dissolution characteristics is not available, therefore, it is not possible to develop and validate a dissolution method. It is simply a scientific impossibility.
Furthermore, the valid scientific principles and testers mean that developed and validated method must be based on experimental conditions which are relevant to applications of the method. In this case, the relevancy aspect comes from the physiological environment of the GI tract in particular intestinal. The only purpose of the test/method is to evaluate dissolution characteristics of a drug product in the GI tract. It is important to note that even for QC purposes the method measures the dissolution characteristics for the GI tract that is why most, if not all, pharmacopeial tests are conducted using physiologically relevant conditions as well. Therefore, the choice of experimental conditions must be physiologically relevant.
A basic or fundamental requirement, in this regard, is that whatever experimental conditions one chooses to represent the GI tract environment, these should remain consistent from product to product or should be product independent, as does the GI tract environment. This is the second flaw (invalid science) of this chapter that it suggests and emphasizes selecting the test product dependent experimental conditions. It will be impossible to determine true and accurate dissolution characteristics of a test product using experimental conditions specific to the product itself. Furthermore, as the experimental conditions change from product to product, which is unlike the GI tract environment, therefore, such tests would be considered invalid for any purpose. No matter how one presents the argument, for product dependent experimental conditions, it will be an irrelevant evaluation method and test.
It is, therefore, critical to understand that the chapter cannot provide help or accurate information for developing or validating a scientifically valid dissolution method.
