Figure 3.

Isobolograms of mixtures of two anaesthetics that both act on the same site show additivity. The fractional concentrations of the drug mixtures required to produce 50% loss of righting reflexes (LoRR) are plotted with the theoretical line for additivity. Each point represents the concentrations of the two drugs, one of which was held constant and the other varied to determine the concentration‐response curve and EC₅₀. L.R. is the linear least squares fit of the data and C.I. is its confidence interval. Shown are combinations of (a): etomidate (Eto) and azietomidate (Azi), both Site 1 anaesthetics; (b): R‐mTFD‐MPAB (MPAB) and R‐mCF₃‐MPAB (CF₃), both Site 2 anaesthetics, and (c): alphaxalone (Alphax) and 3α5βP, both Site 3 anaesthetics.