A Phase III study to assess the clinical utility of low-dose fentanyl transdermal system in patients with chronic non-malignant pain

Background: The transdermal fentanyl delivery system (fentanyl TTS; Duragesic) is currently widely available in patch strengths of 25, 50, 75, and 100 mu g/h. However, a lower dose of 12 mu g/h would allow optimal titration and fine tuning of the analgesic effect, and may be beneficial in certain patient populations such as the elderly or opioid-naive. A 12 mu g/h fentanyl TTS patch has been developed, and the clinical efficacy and safety tested in this single-arm, non-randomized, open-label, multicenter, 28-day trial in opioid-exposed and -naive patients with moderate to severe pain for at least 6 months. Patients: Patients were treated with fentanyl TTS for 28 days in an intent-to-treat manner starting at 12 mu g/h (one patch), titrated upwards in increments of 12 mu g/h to a maximum dose of 36 mu g/h (three patches). Results: A total of 227 patients were enrolled. The majority of patients with a 'global assessment of therapy' of fair/poor at baseline (63.4%) improved to good/very good, while 28.9% of patients with an assessment of good/very good at baseline worsened to fair/poor at endpoint. The average pain intensity levels for the efficacy evaluable population steadily decreased over the course of the trial. The adverse event (AE) profile of fentanyl TTS in this trial was generally similar to that identified in previous fentanyl TTS trials, and no unexpected safety issues or AEs were noted. Furthermore, the drop-out rate in this trial was lower than has been noted in previous trials. Conclusion: This trial demonstrated that the lower 12 mu g/h dose of fentanyl TTS provided a therapeutic benefit in non-malignant chronic pain, with a similar AE rate but a lower drop-out rate than that seen in trials at higher doses. This lower dose may, therefore, be of particular benefit to elderly or opioid-naive patients.