By Eleanor McDermid, Senior medwireNews Reporter
Prolonged-release combined oxycodone/naloxone (OXN PR) may provide relief for patients with severe pain related to Parkinson’s disease, a double-blind randomised trial shows.
During 16 weeks of treatment, patients given OXN PR had less pain than those taking placebo. The differences were significant at 4, 8 and 12 weeks, but not at week 16, which was the primary endpoint.
However, presenting the results at the European Academy of Neurology congress in Berlin, Germany, Anna Sauerbier (King’s College London, UK) noted that the 16-week difference approached statistical significance (p=0.058) and attained it in the per protocol population.
And just three of the 93 patients given OXN PR dropped out because of lack of efficacy, compared with 14 of the 109 patients taking placebo.
All the patients had an average 24-hour pain score of at least 6 on a scale of 0 (no pain) to 10 (worst pain imaginable) over the 7 days before randomisation. Those assigned to take OXN PR did so at a dose of 5.0/2.5 mg twice daily, which could be increased to a maximum of 20.0/10.0 mg twice daily.
“Health professionals seem to be somewhat reluctant to use opioids specifically in Parkinson’s disease without evidence of safety, efficacy or side-effect profilesâ€, observed Sauerbier.
After the double-blind phase, 64 patients from the OXN PR group and 87 from the placebo group entered an open-label phase during which they all received OXN PR.
Sauerbier highlighted that the overall opioid dose used during this phase was lower among patients who had been using OXN PR from the start of the trial, and that the average oxycodone dose used, of 18.8 mg, was less than half the maximum allowed dose and lower than the usual starting dose of 20 mg used in general pain management.
All forms of reported pain improved, but the biggest improvement was seen in nocturnal pain and also in musculoskeletal pain. The latter was also the most common form of pain, occurring in about three-quarters of the patients.
The side-effect profile was as anticipated, Sauerbier reported. Constipation was more frequent in the OXN PR group, but was not severe.
In response to a question from the audience, Sauerbier commented that opioid treatment did not appear to affect the risk of hallucinations, but noted that the overall dose used was relatively low and different results could emerge at higher doses.
However, she described their study as a pilot and said that further research is needed.
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