Figure 3.

Thermal antinociceptive potency of oxycodone, nalfurafine, and three mixture proportions (Experiment 3). Effects of cumulative oxycodone and nalfurafine (mg/kg, i.v.) are depicted as percent maximum possible effect (%MPE) ±SEM across dose of either oxycodone (Figure 3A) or nalfurafine (Figure 3B). Thermal antinociceptive relationship of oxycodone and nalfurafine at the ED₅₀ effect level are depicted as an isobologram in Figure 3C. The y-axis represents the ED₅₀ value and 95% confidence limits in terms of oxycodone dose (mg/kg) and the x-axis represents the ED₅₀ value and 95% confidence limits in terms of nalfurafine dose. The line connecting the ED₅₀ value for oxycodone and nalfurafine alone represents the coordinates of predicted additive values. The dashed line represents values within the 95% confidence limits of additivity.