Table 5. Pharmacodynamic Parameters Estimated for All Models^*(n = 18)

* Based on the pharmacodynamic model: P (Sedation ≥ ss)=C^γ/(C^γ+ C^50,ssγ), where P(Sedation ≥ ss) = probability of level of sedation ≥ SS (2–6); C = plasma benzodiazepine concentration; C^50,ss= plasma benzodiazepine concentration where P(Sedation ≥ ss) = 50%; and γ= slope of probability curve.

† Model H values listed for a 71-yr-old individual.

‡ Observed SS = predicted SS.

§ Observed SS = predicted SS ± 1.

FA = additive fentanyl effect; FS = synergistic fentanyl–benzodiazepine effect; VD = virtual drug effect parameter; K = VD elimination rate constant.