Typical Time Course of Plasma Concentration Following Bolus Injection of an Intravenous Drug, With a Rapid Phase (Red), an Intermediate Phase (Blue), and a Slow Log-Linear Phase (Green) The Simulation Was Performed With the Pharmacokinetics of Fentanyl.

(Reused from Scott JC, Stanski DR. Decreased fentanyl and alfentanil dose requirements with age. A simultaneous pharmacokinetic and pharmacodynamic evaluation. J Pharmacol Exp Ther. 1987;240:159-166.)

Typical time course of plasma concentration following bolus injection of an intravenous drug, with a rapid phase (red), an intermediate phase (blue), and a slow log-linear phase (green). The simulation was performed with the pharmacokinetics of fentanyl.