Results: The pharmacokinetics of intravenous fentanyl reflected a 2-compartment model with a clearance of approximately 1.5 L/min. There was moderate (< 50%) between-subject variability (BSV ...

As found in the separate modeling of the intravenous and nasal data, the 2-compartment model with an estimated bioavailability and an absorption lag for the nasal route was the best fit of the data.