Combination analysis

This chapter describes quantitative methodology that is directed toward assessing interactions between a combination of agonist drugs that individually produce overtly similar effects. Drugs administered in combination may show exaggerated, reduced or predictable effects that are dependent on the specific drug pair and the doses of t h e constituents. The basisfor quantitating these unusual interactions is the concept of dose equivalence which, in turn, is determined from the individual drug dose-effect relations. A common analytical procedure that follows from dose equivalence uses a graph termed an isobologram. We present here an overview of the isobologram, its use and certain related methods that apply to classifying various drug interactions.