Background: Pain is a common adverse effect of RT in patients with HNC, and extended release analgesic options are limited due to high rates of dysphagia. Wax microsphere bound oxycodone was developed as an abuse-deterrent opioid and maintains a similar pharmacokinetic profile whether administered with or without an intact capsule. We hypothesized that microsphere oxycodone could be used for extended release analgesia in patients undergoing RT for HNC and would not need to be discontinued due to dysphagia or gastrostomy tube dependence.

Methods: We performed an open-label prospective clinical trial (NCT03317730) to assess the feasibility of microsphere oxycodone for extended release analgesia during RT for HNC. Participants were > 18y, had histologically confirmed HNC, and were to receive > 50 Gy of RT. Analgesia was prescribed in accordance with the World Health Organization pain ladder. Non-opioid and immediate release opioids were used at the discretion of the treating physicians. Microsphere oxycodone was initiated when total daily opioid dose exceeded 30mg morphine sulfate equivalent and was titrated weekly during RT. The primary feasibility endpoint was frequency of microsphere oxycodone discontinuation within 3 months of RT for reasons other than pain resolution. Secondary endpoints included pain level during RT.

Results: Twenty-six eligible patients were enrolled between June and November, 2018. Microsphere oxycodone was initiated in 13 (50%) patients at a median of 5 weeks after beginning RT (range: 0 – 7 weeks). The mean Brief Pain Index Severity composite score at time of microsphere oxycodone initiation was 5.4 (SD ±2.0) and was 4.8 (SD ±1.5) during the final week of RT (p= 0.21). Six patients utilized a gastrostomy tube to administer microsphere oxycodone for all or part of RT. Microsphere oxycodone was discontinued in 1 (7.6%) patient due to perceived inefficacy, 0 patients due to toxicity, and 0 patients due to difficulty with administration.

Conclusions: These results support the feasibility and safety of microsphere oxycodone for extended release analgesia in patients with HNC undergoing RT. Future research should compare microsphere oxycodone and transdermal fentanyl in this population.