There are about 500+ dissolution methods listed in the FDA database and about 600+ methods (monographs) in the USP. In addition to these, there are many more, perhaps in the hundreds, dissolution methods described in literature. Moreover, as part of new product development exercises, it is a common and expected practice to develop additional new or revised methods.
It may be interesting to note that the objective of drug dissolution testing has never been to develop methods, but to determine/estimate drug dissolution/release characteristics of products. By developing drug and/or product specific dissolution tests, one in fact would never know or determine the actual dissolution characteristics of any product. The current practices of method development simply defeat the purpose of products evaluation.
For products evaluation, one requires a test/method which is independently developed and established. Therefore, current practices of method developments are not only scientifically invalid and useless but also a waste of time and resources.
The use of the crescent shape spindle, with a common set of experimental conditions, is suggested to address the current difficulties. The suggested approach not only practically eliminates the need for method developments, in particular product dependent, but also provide a scientifically sound and valid drug dissolution testing and product evaluation approach (e.g. see link, link2).
The following links may be useful for further information regarding the difficulties of the current practices:
- Drug Dissolution Testing – A serious concern! (link)
- Costly mistake formulators/analysts often make i.e. developing a product dependent dissolution test (link)
- Selecting a Dissolution Apparatus – Some Practical Considerations (link).
- (Developing) a discriminatory vs bio-relevant test (link)
- Method Validation: A Unique Problem Concerning the Drug Dissolution Testing (link)
- Where does 20% of the drug go? (link)
- Dissolution method development – a practice which causes confusion and hinders in product evaluation. (link)
- Drug Dissolution Testing Mosaic. (link)
- Product dependent dissolution testing – a scientifically invalid practice. (link)
- How to conduct a dissolution test? A simple question, but confusing answers. (link)
- An incorrect reason for developing and conducting a dissolution test. (link)
- Method development practices: Are these achieving their intended purpose? (link)
- Dissolution method development – what it is not! (link)
- Generics and discriminatory dissolution tests (link)
- Validation (Method/Apparatus) Practices (link).
- Selecting an apparatus and its associated experimental conditions for testing (link).
- The science of drug dissolution testing: Testers or apparatuses, experimental conditions and interpretation of results – A systematic approach for learning (link)
