Commonly described dissolution methods are product dependent. Therefore, it is not possible to know whether the observed dissolution characteristics are a reflection of the product (formulation and/or manufacturing) attributes or because of the experimental conditions (apparatus, rpm, medium etc.) employed.
For an appropriate and accurate assessment of dissolution characteristics of a product, the dissolution method must be product independent. The use of crescent shape spindle has been suggested based on this principle, thus provide true dissolution characteristics of a product. Please see the following links, for further discussion:
(1) http://www.drug-dissolution-testing.com/?p=449#more-449
(2) http://www.drug-dissolution-testing.com/blog/files/Flyer.pdf
(3) http://www.drug-dissolution-testing.com/?p=826
(4) http://www.drug-dissolution-testing.com/?p=1136
(5) http://www.drug-dissolution-testing.com/?p=1061#more-1061