As a common practice, analysts prefer to use compendial methods, if available to evaluate pharmaceutical products. There are clear advantages of using such methods, as the results obtained are easier to be accepted by third parties, including regulatory agencies.
On the other hand, in some cases, where compendial methods lack desired characteristics or have flaws, such a practice seriously hampers the appropriate testing and thus proper evaluations of the products. This leads to significant frustrations on analysts’ part and demands for a large resource (human and financial) burden on the pharmaceutical industry.
The drug dissolution testing appears to fall in this category where the literature clearly shows that the currently used compendial apparatuses (paddle/basket) do not provide reproducible and relevant results. Although these flaws have generally been recognized, addressing the issue would take time.
During this transitional period of addressing the issue, analysts may use alternate methods to obtain reproducible and relevant results and then adjust the experimental conditions using paddle/basket apparatuses to obtain the “expected” results. Such an approach would be perfectly acceptable under current compendial practices as using the paddle and basket apparatuses, one never determines the relevant and reproducible dissolution results. Analysts usually adjust the experimental conditions (apparatuses, rpm, media, etc.) to obtain the “expected” dissolution results. The question is how to obtain the “expected” dissolution results.
New approaches have been described in the literature to obtain such “expected” results. One such approach is the use of a crescent-shaped spindle which has been shown to provide product independent dissolution results using common and pre-defined experimental conditions. One may use vessel-based apparatuses with the crescent-shaped spindle to obtain the “expected” dissolution results.
Taking this approach, one would have the expected (or “true”) dissolution characteristics of the product and then develop experimental conditions using paddle/basket apparatuses to obtain the “expected” results using compendial approaches. Using such an approach would help meet the compendial requirements and provide the data using the alternate approach for modifying/improving current compendial methods—a win-win situation.