The analysis of dose-response curves--a practical approach.

The rationale for the objective assessment of dose-response curves (DRCs) is presented. Using data derived from isoprenaline/heart rate responses studies, two new statistical methods of objectively defining the terminal linear segment of an incomplete DRC are presented. Using data derived from phenylephrine/diastolic blood pressure response studies, the parallel shift quadratic model of Sumner et al. (1982) has been extended to include a measure of the suitability of the quadratic model for each individual data set using the Akaike information criterion. A parallel shift Emax model is proposed for complete DRCs.