Table 4. Parameter Describing the Interaction Model 13 for Remifentanil and Propofol
γ= Steepness factor determining the slope of the concentration–response relationship; U50(0.5) = potency of the drug combination at ratio 0.5 relative to the normalized potency of each drug by itself. Values less than 1 indicate synergy; C50= concentration associated with 50% of the maximum effect.