The use of experimental designs in tablet formulation

In the optimization of tablet formulations, different approaches can be used. The one variable at a time method requires many experiments and there is no guarantee that an optimal formulation is achieved. Moreover the interaction between different factors, which may influence the tablet properties, will not be detected [10]. The use of an experimental design can be helpful in the optimization of tablet formulations. Mixture designs can be used to describe the response (tablet properties) as a function of the 

In a factorial design different variables can be varied independently. The effect of the variables as well as the interaction between the variables on the response can be described [12, 13]. 

Many papers have been published in which an experimental design is used to optimize tablet formulations. Both process variables as well as compositional variables (quantitative and qualitative) were used as independent (adjustable) variables. The studied dependent variables (factors to be optimized) are physical tablet properties directly after preparation such as weight variation, crushing strength, dissolution profile, disintegration time and friability. Doombos reviewed papers in which statistical methods were used to optimize tablet formulations [13]. 

Experimental designs also have been used to study the influence of tablet composition and storage conditions on the chemical stability (degradation of the drug) [e.g. 14-17]. 

---