Pharmacokinetics of transdermal fentanyl in the peri‐operative period in young children

The pharmacokinetics of transdermal fentanyl were assessed in eight children aged 18–60 months, weighing 11–20 kg and monitored postoperatively in the intensive care unit. A patch, delivering 25 µg.h−1 of fentanyl, was applied for 72 h from the induction of anaesthesia. Plasma fentanyl concentrations were measured over 144 h. Mean (SD) peak concentration of fentanyl was 1.7 (0.66) ng.ml−1 and time to reach maximal plasma concentration was 18 (11) h. The elimination half‐life was 14.5 (6.2) h, and the area under the curve for plasma fentanyl concentration (0–144 h) was 86.8 (27) ng.h.ml−1. Maximal fentanyl concentration was negatively correlated with patient age (r = − 0.71; p = 0.049) but not with body weight. These results suggest that the pharmacokinetics of transdermal fentanyl in children are similar to those in adults.