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. Author manuscript; available in PMC: 2016 May 1.
Published in final edited form as: Neurotoxicology. 2015 Mar 14;48:100–108. doi: 10.1016/j.neuro.2015.03.007

Figure 3. Isobologram depicting prevention of TMDT-induced 24 h lethality by DZP, MK-801 and their combinations.

Figure 3

(a) As in Figure 2, ED50s ± 95% CI of DZP (downwards triangles) and MK-801 (upwards triangles) administered singly were plotted on the x and y axes, respectively. The line of additivity connects these ED50s. Open circles: Theoretical ED50 ± 95% CI for inhibition of 24 h lethality by DZP:MK-801 3:1. Closed circles: Actual ED50 ± 95% CI of the DZP:MK-801 3:1 combination. This dose was significantly below the theoretical point of additivity (p<0.0299). Dotted lines: depict the 3:1 and 11:1 DZP:MK-801 fixed ratios.

(b) Dose Reduction Table compares the ED50 doses of DZP and MK-801 predicted for an additive interaction and the actual doses for the 3:1 combination. The reduction in dose required to obtain a 50% reduction in 24 h lethality was much greater than predicted, reflecting a synergistic interaction of the combination.