Drug interactions represented by high resolution computer graphics.

The amount of backward walking induced in mice by co-administration of clenbuterol, a beta-adrenoceptor agonist and putative antidepressant, and the benzodiazepine chlordiazepoxide was plotted as a three-dimensional surface, using modified Uniras software. The surface was compared with the theoretical surface to be expected if the interactions between the two drugs were merely additive. The difference between the theoretical and the obtained surfaces was plotted and a functional representation of statistical variability was 'draped' over the difference model. The computer methods can be applied to small amounts of irregularly distributed data, and results are apparent from simple inspection, e.g. the highest peak of backward walking is also the most reliable statistically. The technique is useful for both laboratory and clinical studies.