Drug dissolution testing is often described as a quality control tool for the assessment of pharmaceutical products, such as tablet and capsule, by establishing batch-to-batch consistency in their production (see). The question is what quality and consistency here one refers to? Saying it in another way, if an analyst conducts a dissolution experiment and obtains certain results, how these results are linked to the quality of the test products. If establishing repeatability/reproducibility/consistency of a product and/or results is the objective, then why can this be achieved ONLY by conducting a dissolution test , when other tests can also be done, e.g., disintegration or grinding (to achieve consistent fine powder). If a product disintegrates or ground to fine powder then expected batch-to-batch consistency is established. There is actually no need to conduct a dissolution test for such a purpose. Manufacturers and regulators have to consider this aspect carefully as to why a dissolution test is necessary to establish batch-to-batch consistency.
On the other hand, if a dissolution test as a solution formation test is needed then perhaps one can do a test using a 50/50 solution of water and ethanol with stirring for half an hour at an rpm of 150 for all products. It is not necessary that the entire drug has to be released or dissolved as long as the results are consistent and reproducible. Such a test can also meet the requirement of a consistency test.
Moreover, a dissolution test is suggested as a consistency test, however, there appears to be nothing consistent about the test itself. For example, one may use any apparatuses (mostly paddle or basket), with any rpm (mostly 50, 75 or 100) using any volume of medium (mostly 250, 500, 900 mL or 1L) having any pH (mostly 1, 4.5, 6.8) of any strength (mostly 0.01 to 0.1M) and having any solubilizing agent (mostly SLS). Further, a dissolution test can be run for any duration of time from 15 minutes to 24 hours. There are no criteria in choosing a consistent experimental condition other than choices based on the discretion of a formulator/analyst to achieve certain DESIRED dissolution characteristics of the product.
In short, a dissolution test as it is conducted or suggested currently does not appear to provide scientific or logical support so that it can be considered as a test to monitor batch-to-batch consistency of pharmaceutical products.
So why is a dissolution test conducted? The only reason the test is to be conducted is to assess in vivo dissolution characteristics of a product. This is a very important concept/requirement which somehow has been overlooked and requires urgent attention.
