Evaluation of synergism or antagonism for the combined action of antiviral agents.

The criteria used for the evaluation of synergism or antagonism for the combined action of antiviral agents are critically reviewed. The isobole method is the only generally applicable approach which does not require any assumptions about the shape of dose-response curves. A microcomputer-based isobole method is proposed which constructs response surfaces and a complete set of isoboles in the dose range under study from a relatively small number of experiments. The objective of this work is to take a step towards standardization of definitions, terminology, and methods for the evaluation of synergism or antagonism in antiviral drug combination experiments.