Fentanyl buccal tablets for breakthrough pain in highly tolerant cancer patients: preliminary data on the proportionality between breakthrough pain dose and background dose

Context: Cancer patients receiving high doses of opioids as background medication are challenging, and it would be useful clinically to know whether a rapid-onset opioid (ROO) for breakthrough cancer pain (BTcP) may be started at a dose proportional to the background opioid dose.

Objectives: The aim of this study was to assess the efficacy and safety of the fentanyl buccal tablet (FBT) in doses proportional to the opioid dose administered for background analgesia in a sample of patients with BTcP who were receiving high doses of opioids.

Methods: Twelve patients who were receiving opioids for background analgesia at doses equivalent to more than 500 mg of oral morphine and had adequately controlled pain were prospectively recruited. BTcP was treated with proportional doses of FBT: patients receiving 600 mg of oral morphine equivalents were administered 1000 μg of FBT, patients receiving 900 mg of oral morphine equivalents were administered 1500 μg of FBT, and so on. For each episode of BTcP, trained nurses collected pain intensity (on a 0-10 numerical rating scale) and emerging problems when called for increases in pain considered to be severe in intensity by patients (T0) and 15 minutes after FBT administration (T15).

Results: Patients were receiving mean doses of oral morphine equivalents of 1340 mg (± 585; range 720-2400). Seventy-nine events were treated with FBT (6.6 ± 4.9 for each patient). The median pain intensity of BTcP events was 8 (range 7-10), and the mean dose of FBT administered was 2233 μg (± 975; range 1200-4000). In most events, a decrease in pain intensity >33% and >50% was observed (n=14 and n=48, respectively) 15 minutes after the administration of FBT. Data on 11 episodes were missed. Only six events were unsuccessfully treated. In all the patients, the level of adverse effects after FBT administration was mild and indistinguishable from that associated with the background opioid analgesia.

Conclusion: FBT in doses proportional to the high doses of opioids used for background analgesia was efficacious and well tolerated when administered for BTcP. Controlled studies with a specific design and a large number of patients should confirm such preliminary results.