Dissolution Assay Development for in Vitro-in Vivo Correlations

To obtain an in vitro-in vivo relationship (IVIVR), two sets of data are needed. The first set is the in vivo data, usually a pharmacokinetic metric derived from a plasma concentration profile (e.g., AUC, Cmax, % Absorbed, etc.). The second data set is the in vitro data. This is usually drug release data from a dissolution test and most often takes the form of percent dissolved as a function of time. A mathematical model describing the relationship between these data sets is then developed. While fairly obvious, it should be pointed out that when trying to develop an IVIVR, the in vivo data is fixed. Once this data is generated, it establishes the relevant performance of a particular dosage form or series of formulations. The in vitro drug release profile, on the other hand, may be modified through changes in the dissolution test conditions. It is the goal of the pharmaceutical scientist to vary in vitro conditions such that a dosage form or formulation series behaves in a manner similar to that found in vivo.