Benefits of transdermal fentanyl in patients with rheumatoid arthritis or with osteoarthritis of the knee or hip: an open-label study to assess pain control.

OBJECTIVES: To evaluate the effectiveness and safety of transdermal fentanyl (TDF) for the treatment of pain associated with rheumatoid arthritis (RA) or osteoarthritis of the knee or hip (OA), which was not adequately controlled by non-opioid analgesics and/or weak opioids.

METHODS: The study design incorporated a 1-week run-in period when current analgesic medications were optimised, a 28-day treatment period and a 1-week taper-off period. Patients with RA (n = 104) and OA (n = 159) started treatment with TDF 25 microg/h. Patches were replaced every 72 h, with the option to up-titrate until adequate pain control was achieved. Metoclopramide was taken during the first treatment week and as needed thereafter.

RESULTS: 203 patients completed the treatment phase, 90 entered the taper-off phase. 25 microg/h was the most frequently used maximum dose (51%). Pain control was increased from 4% to 29% of patients during run-in. The number of patients reaching adequate pain control in the first treatment week was increased to 75%, and increased further to 88% on day 28 and to 80% at endpoint. From baseline (screening) to endpoint, there were significant reductions in pain (p < 0.001) on the Wisconsin Brief Pain Inventory, and significant improvements in quality of life (Short-Form-36: physical p < 0.001; mental health p < 0.05). Eighty per cent of the patients (n = 134) assessed the treatment favourably; nausea and vomiting were the most common adverse events, mainly occurring at treatment initiation. Efficacy of metoclopramide appeared limited. TDF could be initiated in patients pre-treated with non-opioid analgesics or weak opioids and tapered off without major complications.

CONCLUSIONS: TDF significantly improved pain control and quality of life, and was well tolerated in patients with RA or knee/hip OA who continued to experience pain on their current analgesic treatment. Treatment could be discontinued without issues. Nausea and vomiting was usually mild during treatment initiation. Patients' well being could be further accommodated by optimising prophylactic treatment.