Efficacy of reconstituted intravenous fentanyl to sublingual solution versus oral morphine syrup for breakthrough pain among patients with chronic gynecologic cancer pain: A randomized, double‐blind, placebo‐controlled trial

Abstract Rapid‐acting fentanyl formulations are superior to oral morphine (OM) syrup in controlling breakthrough pain among patients with cancer, but they are expensive and unavailable in many countries. Objective To evaluate the efficacy of reconstituted intravenous fentanyl to sublingual solution (IFS) in relieving breakthrough pain as compared with OM. Methods In this randomized, double‐blind, double‐dummy, placebo‐controlled trial, patients with gynecologic cancer aged ≥18 years experiencing chronic cancer pain with breakthrough pain were enrolled. Patients were randomly allocated (1:1) to receive either 50 μg IFS or 5 mg OM. Pain intensity level was assessed at 5, 15, 30, 45, 60, and 120 min after treatment. The primary outcome was the reduction in pain intensity at 15 min in the intention‐to‐treat population ( ClinicalTrials.gov , NCT05037539). Results Between June 15, 2021 and December 30, 2021, 40 participants were equally and randomly assigned to receive IFS or OM. The primary outcome was significantly higher in the IFS group (4.25 vs. 1.05, p < 0.0001). The secondary outcomes also showed higher reduction in pain intensity at 5 min in the IFS group. Subsequent breakthrough pain did not differ between the two groups. However, the reduction in pain was lower in the IFS group at 45, 60, and 120 min, where pain was classified as mild. No severe adverse effects were observed in both groups. Burning sensation without noticeable lesion was found in 20% of the IFS group. Conclusion IFS can reduce early breakthrough pain. IFS may be considered for breakthrough pain when rapid‐acting fentanyl formulations are unavailable.