3-Dimensional Surface Plot

Response Surface Plot

Formulation and process optimization can be done statistically with the use of experimental design for estimates of the best processing parameters and excipient and lubricant levels.  Controllable variables in tableting are mainly the precompression and compression forces and tablet press speed, as well as the formulation component levels.  Response variables include the ejection force, tablet hardness and friability, dissolution rate, and drug stability.  The purpose of an experimental design is to perform a series of experiments in order to determine some levels of factors that will allow you to achieve an optimal level of dependent variables.  The experiments should be designed so as to minimize effort and maximize statistical reliability of the results.  The majority of published work in this area deal with response surface designs that produce a predictor polynomial equation for each response variable under consideration.  A multidimensional surface is then searched for the best ranges of factor variables that, when plugged in the equations, result in the optimal value of the responses.  In this plot, the optimal (highest) hardness is obtained when the compression force is in the 3000-4000 lbs. range with as much MCC in the formulation as possible.