Transdermal fentanyl for pain control in adults with chronic cancer pain

The transdermal therapeutic system (TTS) for fentanyl is a drug-delivery system for use in patients with chronic pain who require an opioid analgesic. A multicentre, randomized, double-blind, placebo-controlled study was performed to evaluate the efficacy and safety of TTS-fentanyl as an analgesic for chronic cancer pain. One hundred and thirty-eight patients entered a 15-day dose-titration period, followed by a 9-day double-blind period (95 patients) with TTS-fentanyl or placebo. Fifty-five patients entered a follow-up period of indefinite duration. For the majority of patients, TTS-fentanyl 50-75 µg/h provided effective analgesia. Due to an unexpectedly high placebo response, it was not possible to show fentanyl to be statistically superior to placebo at the 5% significance level. Nine patients treated with fentanyl and 13 treated with placebo were withdrawn from the study during the double-blind therapy because of insufficient efficacy (not significant), while 66% of fentanyl-treated patients experienced effective pain control compared with 48% of placebo-treated patients (p=0.071). During the course of the double-blind therapy, the mean dose of rescue morphine increased slightly more in the placebo group than in the fentanyl group. At the end of the double-blind phase, the investigators rated trial medication as being 'good' or 'excellent' in 30 patients in the fentanyl group and 23 in the placebo group. TTS-fentanyl appeared to be well tolerated, with a low incidence of constipation, somnolence and nausea. Due to an unexpectedly high placebo response it was not possible to demonstrate fentanyl to be statistically superior to placebo. This may reflect the practical difficulties of performing clinical trials in cancer patients with great inter-individual variability. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.