It is often suggested that to obtain appropriate dissolution characteristics of a product one may use or select an apparatus depending on the product attributes and/or desired release characteristics such as discriminating profiles, reproducibility, bio-relevancy, etc. Such reasoning dictates that the analyst/formulator should have an idea about the expected outcome of the results, whether based on an educated guess or from prior experimentation. Thus, by selecting a particular apparatus and/or its associated experimental conditions, one is trying to achieve the results reflecting one’s expectation.
For example, when one conducts an experiment using the paddle apparatus and finds dissolution results of a tablet product, and their variability, higher than expected while observing that some, or all, tablets are floating within the vessel during testing. Such behavior or experiment is commonly considered flawed or inappropriate. A common practice to rectify this “problem” is to either use the basket apparatus or a sinker to restrict this floating behavior assuming that this may be causing higher results and variability. This means that the analyst/formulator already has a preconceived idea/expectation about the results and variability of the product, and is trying to obtain those results by adjusting the means, in this case by using a different apparatus or a sinker. Obviously, the analyst is not determining dissolution characteristics of the product but achieving intended results by adjusting tester and/or associated experimental conditions. Read the rest of this entry �