Table 1. Pharmacokinetic Parameters of Alfentanil (± SE) during Sessions A and B, Estimated by NONMEM with the Presence or Absence of Propofol as Covariate

The coefficient of variation was calculated as the square root of the variance of η.

CV = coefficient of variation; V¹= central volume of distribution; V²= small peripheral volume of distribution; V³= large peripheral volume of distribution; Cl¹= elimination clearance; Cl²= rapid distribution clearance; Cl³= slow distribution clearance; t^lag= lag time.