Figure 4

Model predictions for combination drugs of a partial agent A and full agent B. The isobolograms for the (a) Loewe model and (b) Hand model. (a) The Loewe model assigns reference effects only to dose pairs below the horizontal limit isobole at effect value E_max,A, beyond which it can be extended via the HSA model. (b) Above the partial agent A’s maximal effect value its sensitivity is set to 0. As soon as the combined curve passes the curved limit isobole (a^*, b^*) at effect level E_max,A it is driven by the full agent alone.