Response to intravenous fentanyl infusion predicts subsequent response to transdermal fentanyl

Prediction of the response to transdermal fentanyl (FENtd) before its use for chronic pain is desirable. We tested the hypothesis that the response to intravenous fentanyl infusion (FENiv) can predict the response to FENtd, including the analgesic and adverse effects.

The study subjects were 70 consecutive patients with chronic pain. The response to fentanyl at 0.1 mg diluted in 50 ml of physiological saline and infused over 30 min was tested. This was followed by treatment with FENtd (Durotep MT patch 2.1 mg) at a dose of 12.5 µg/h for 2 weeks. Pain intensity before and after FENiv and 2 weeks after FENtd, and the response to treatment, were assessed by the numerical rating scale (NRS), clinical global impression-improvement scale (CGI-I), satisfaction scale (SS), and adverse effects.

The NRS score decreased significantly from 7 (4-9) [median (range)] at baseline to 3 (0-8) after FENiv (p < 0.001), and to 4 (1-8) after FENtd (p < 0.001). The effects of FENiv, as evaluated by ΔNRS, CGI-I, and SS, were significantly greater than those of FENtd (p < 0.001, each), but not by the frequency and the severity of adverse effects, with the exception of dizziness. ΔNRS, and severity of adverse effects (drowsiness, dizziness, nausea, dry mouth, and pruritus) of FENiv correlated significantly with those of FENtd (rs > 0.04, each).

The analgesic and side effects after intravenous fentanyl infusion can be used to predict the response to short-term transdermal treatment with fentanyl.