Drug dissolution tests are conducted to determine the dissolution/release characteristics of a product. Therefore, one requires a pre-established set of experimental conditions (apparatus, rpm, medium volume or pH, etc.) independent of the product to determine the actual or true characteristics (i.e. dissolution).
However, current practices, in particular using paddle and basket apparatuses, require that the analyst MUST first know, or anticipate, dissolution characteristics of the test product and then ADJUST experimental conditions to achieve the desired or anticipated results. As dissolution method development practices, selections or adjustments of such experimental conditions are then described or promoted incorrectly. Almost every product came with its own set of experimental conditions and expected dissolution results (commonly referred to as Tolerances). At present, one cannot know or determine the actual or true dissolution characteristics of the products. It is, therefore, very important and critical to note that current practices of dissolution testing are practically a complete waste of time and resources.
The suggestion of dissolution testing using the crescent-shaped spindle, along with a single set of experimental conditions (which are product independent as well) addresses the current issues and provides a simple, practical, and scientifically valid approach for dissolution testing. For further detail, please see these links (1, 2, 3).