Transdermal fentanyl for the relief of pain after upper abdominal surgery

Transdermal fentanyl (n = 22) was compared with placebo (n = 18) in a double-blind study of pain after upper abdominal surgery. All patients also received i.v. morphine on demand for supplementary analgesia. The transdermal systems were applied 2 h before induction of anaesthesia and remained in situ for 24 h. After operation, pain scores were significantly lower and peak expiratory flow rates significantly higher in the transdermal fentanyl group, who demanded significantly less morphine than the control group. Mean plasma fentanyl concentrations at 12 and 24 h were within the therapeutic range (1.5 and 2.0 ng ml-1, respectively).