The terminology of “developing IVIVC” is often used in the area of drug dissolution testing, which reflects developing a relationship between in vitro (dissolution) and in vivo (bioavailability) results. However, the statement appears redundant, as this relationship always exists between in vitro and in vivo results. In fact, the existence of this relationship (IVIVC) forms the basis of dissolution testing practice.
So, then the question is, why are these IVIVC development studies frequently conducted and described in the literature? The reason may be explained as follows:
The apparatuses commonly used for dissolution testing, particularly paddle and basket, do not provide relevant dissolution results as they do not appropriately simulate an in vivo environment. So, instead of using apparatuses that would appropriately simulate an in vivo environment, studies are conducted to find or “develop” experimental conditions to obtain in vitro results that match the in vivo results. Thus this practice of developing product-specific experimental conditions (apparatus, medium, rpm, etc.) has become known as “developing IVIVC”. However, this practice of IVIVC does not serve any useful purpose for predicting in vivo results, relating in vitro results to in vivo outcomes or assessing drug release characteristics of the product. Having said that, the question then becomes, what is the intended purpose of IVIVC development? The purpose is not to develop IVIVC, as stated above, this relationship always exists, but to determine/predict the drug concentrations in blood utilizing the IVIVC concept. Thus, the practices of IVIVC and dissolution testing are for establishing (calculating/predicting) drug concentration-time (C-t) profiles in humans. For a more detailed discussion on this subject, along with a description of a simple method for determining C-t profiles, please see the article (The Open Drug Delivery Journal, 2010, 4, 38-47. (Link).