Long-Acting Opioid Shows Promise for Parkinson’s Disease Pain

man in pain parkinson's
man in pain parkinson’s
Although the primary endpoint was not significant, notable improvements in pain were observed at different time points.

Patients with Parkinson’s disease often suffer from debilitating chronic pain, but research indicates that a long-acting opioid-based treatment may be safe and effective.

Professor Claudia Trenkwalder, MD, of Paracelsus-Elena Hospital in Kassel, Germany, and colleagues assessed the analgesic efficacy of prolonged-release oxycodone-naloxone (OXN PR) in Parkinson’s patients with severe, chronic pain. All patients enrolled (n=202) had Hoehn and Yahr Stage II-IV Parkinson’s disease and at least one type of severe pain with an average 24-hour pain score of at least 6 on a 10-point scale. The primary endpoint was average 24-hour pain score at 16 weeks, and secondary endpoints included frequency of rescue medication use, percent of responders (≥30% reduction from baseline) in 24-hour pain at 16 weeks, and percent of responders for Clinical Global Impression Improvement (CGI-I) and Patient Global Impression Improvement (PGI-I)at 16 weeks.

Patients were randomized to either oral OXN PR (n=93; oxycodone 5 mg and naloxone 2.5 mg 2x/d) or placebo (n=109) for 16 weeks, with full analysis population being 88 patients vs. 106 patients. Least squares mean average 24-hour pain score at 16 weeks in full analysis population was 5.0 (95%CI; 4.5 to 5.5) in the OXN PR group compared to 5.6 (5.1 to 6.0) in the placebo group (difference −0·6, 95% CI −1.3 to 0.0; P=0.058). Although the primary endpoint was not met, statistically significant differences were observed for secondary endpoints that indicate a positive effect.

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OXN PR was associated with statistically significant improvement at week four (P=0.018), week eight (P=0.011), and week 12 (P=0.021). When taken in line with study protocol, OXN PR was associated with a significant improvement in average 24-hour pain score at week 16 compared to placebo (P=0.010). Researchers also observed a greater responder rate for 24-hour pain control with OXN PR (P=0.021), less use of rescue medication, and significant improvements in CGI-I (P=0.019) and PGI-I (P=0.022), as well as improvements in sever musculoskeletal pain (P=0.023) and severe nocturnal pain (P=0.010) compared to placebo.

“The encouraging secondary endpoint data suggest that further studies may help to uncover the potential role of OXN PR in this patient population,” Professor Trenkwalder said in a news release. “This study adds to the very limited knowledge base on the efficacy and safety of opioid-based treatment of patients with Parkinson’s disease suffering from complex pain.”

Overall, nearly the same proportion of patients taking OXN PR or placebo experienced adverse events (65% vs. 70%), including treatment-related adverse events (57% vs. 57%) and serious adverse events (5% vs. 6%). Treatment-related nausea (17% vs. 9%) and constipation (17% vs. 6%) was more common in the OXN PR group compared to those taking placebo.

Despite not meeting the primary endpoint, the study results imply a positive role for OXN PR for Parkinson’s pain, and the researchers encourage further research to be conducted on OXN PR in this population.

References

  1. Trenkwalder C et al. Lancet Neurol. 2015; doi:10.1016/S1474-4422(15)00243-4.
  2. Mundipharma news release