Introduction: Oral mucositis is a painful side effect to chemotherapy. Orally applied opioids may offer analgesia with fewer side effects than systemic opioids.
Methods: A randomized trial comparing the analgesic effect of a morphine oromucosal solution (OM) to placebo and a positive control group receiving intravenous (IV) morphine as an add-on treatment to morphine patient-controlled analgesia (PCA) in a mixed population of paediatric and adult haematology patients. All patients in the study were equipped with a morphine PCA pump and the participating patients were instructed to use this pump as an escape. Primary outcome was morphine consumption (mg/kg/hour) on the PCA pump. Secondary outcomes included pain intensity difference at rest and when performing oral hygiene, time to first PCA bolus, nutrition intake and adverse events.
Findings: A total of 60 patients (38 children <18 years) were randomized. Thirty patients were allocated to morphine OM/placebo IV (group MO), 15 patients to placebo OM/morphine IV (group MI) and 15 patients to placebo OM/placebo IV (group P). The median morphine consumption in the MO group (22.7 mcg/kg/hour 95% confidence interval (CI) 19.4–29.4 mcg/kg/hour, p = 0.38) was not significantly different from the placebo group (24.6 mcg/kg/hour 95% CI 16.8–34.4 mcg/kg/hour, p = 0.44) or the MI group (13.7 mcg/kg/hour 95% CI 9.7–37.8 mcg/kg/hour). For the secondary outcomes, the analysis of summed pain intensity difference after the first, third and fourth administrations of study medication indicated a reduction in pain for the MI group compared to the P and MO groups. No serious adverse events were reported.
Conclusion: The findings indicate that the analgesic effect of peripherally applied morphine is not significantly different from placebo, and parenteral opioids should continue to be the standard of care.