A dissolution test – a QC test or is it?

Quality control (QC) aspect of dissolution testing is linked to the release characteristics of drug from its product, commonly tablet or capsule. This release characteristic, which is measured in vitro, is supposed to reflect/simulate drug release in vivo. Therefore, the QC test is a reflection of drug release in vivo in humans, thus establishes the quality of product. That is why, such tests are conducted using experimental conditions which simulate human physiological conditions of GI tract as closely as possible. However, recent studies (see publication section) reflect that experimental conditions used (e.g. apparatuses) do not simulate appropriate GI tract environment such as they lack the needed mixing and stirring in the dissolution vessels. Therefore, current practices of dissolution testing may not reflect quality of the products and the test may not be considered as a QC test.

On the other hand, considering this lack of QC aspect, commonly dissolution test is presented as a test for consistency check for batch to batch evaluations, but still appears to be implied as a QC test. This obviously creates significant confusion in properly describing and/or differentiating the test as a QC or consistency-check test. As stated above in its current form dissolution test does not appear to be a QC test, therefore, it should be considered as a consistency-check without its link to in vivo release and to the quality of the product.

As a consistency-check test, it may be performed using any of the experimental conditions which may or may not be physiologically relevant. For example, organic solvents vs aqueous based, higher or lower temperatures vs 37 ºC, any other type of stirring device (magnetic bar, shakers, propeller with high speed motors etc) vs commonly used paddle and basket apparatuses. Further, one may report the results for any sampling time which appear to be most stable and reproducible. Obviously, this has never been the intent that the dissolution test be conducted in this manner, in particular as a QC test.

Therefore, to conduct a dissolution test as a QC test, as was originally intended, the test has to be conducted by creating or simulating more appropriate physiological environment, i.e. improved stirring and mixing. This improved stirring and mixing aspect indeed appears to address the limitations of current practices and its artefacts. For further discussion on this topic please see the recent literature under the publication section.

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