Figure 60-7 Plasma fentanyl levels in 10 children who ingested the liquid intravenous formulation of fentanyl. The peak plasma levels achieved were nearly identical to those achieved with a similar dose of the Fentanyl Oralet.^{[181] [182]} Like the Fentanyl Oralet, there was large patient-to-patient variability and a long slow elimination curve. The advantage is that the intravenous formulation is much cheaper and there is no problem with variable consumption time. (Redrawn from Wheeler M, Birmingham PK, Lugo RA, et al: Pharmacokinetics of the intravenous formulation of fentanyl citrate administered orally in children undergoing general anesthesia. Anesth Analg [in press].)