At the product development stage the objective is to develop a product (tablet/capsule) having certain desired drug release/dissolution characteristics in humans. Therefore, one requires a dissolution method mimicking in vivo or the GI tract environment (in particular that of the intestinal). Commonly, this in vivo environment for dissolution testing purposes is represented by three variants: (i) temperature (37 ºC); (ii) an aqueous based solvent/medium; (iii) a container or vessel with a stirrer to provide interaction between product and solvent.
Another requirement, which is perhaps the most critical one and is often overlooked, is that the method or testing environment must also be product independent as does the GI tract environment.
It is further important to note that the method to be used must have already been developed and validated independently of the product which is underdevelopment. On the other hand, it is a common practice that people use or develop product dependent dissolution methods. However, unfortunately such a practice is neither scientifically valid nor correct. Furthermore, the use of a product dependent method cannot provide true or actual dissolution characteristics of the product (link).
At present, none of the commonly suggested/recommended testers/methods, including pharmacopeial, provide common and/or product independent methods or experimental conditions. Thus such tests/methods cannot provide scientifically valid and/or true dissolution characteristics of a product during the product development stage.
This present day limitation can easily be addressed with the use of the crescent-shape spindle set at 25 rpm with 900 mL of water maintained at 37 ºC. A small amount solubilizer may be added to water/medium if the drug is of low aqueous solubility. For more details regarding advantages of using crescent-shape spindle please follow the link.
