Efficacy and safety profile of prolonged release oxycodone in combination with naloxone (OXN PR) in Parkinson's disease patients with chronic pain

Pain is a relevant and often underestimated non-motor symptom affecting the quality of life of patients with Parkinson's disease (PD). Although some pain symptoms can be effectively treated by dopaminergic medication, a correct diagnosis of the different types and distribution of pain in PD is challenging, and accordingly, its treatment remains troublesome. We evaluated the efficacy and the safety of a prolonged release oral formulation of oxycodone hydrochloride combined with naloxone hydrochloride dehydrate, in a fixed ratio of 2:1 (OXN PR). A total of 16 PD patients with history of pain with a minimum intensity of four on numerical rating scale (NRS) received low-dose OXN PR (5/2.5 mg twice daily) and were observed for a period of 8 weeks. The primary efficacy measure was the pain severity measured with NRS and Brief Pain Inventory (BPI). Secondary efficacy measured the safety profile by recording the occurrence of side effects, clinical global impression of change (CGI-C), Parkinson's disease sleep scale 2 (PDSS-2), Bowel function index (BFI). Data were collected and analyzed using descriptive statistics. Patients who completed the study (14 out of 16) reported a significant pain relief as observed by the reduction of NRS and BPI scores. No adjustment of dopaminergic therapy was required. No significant changes were observed in bowel function and constipation symptoms as measured by the BFI during the 8-week period. Similarly, no changes were observed in PDSS-2 score, whereas an improvement was recorded by CGI-C compared to baseline. Low-dose oral OXN PR was efficacious for the management of pain symptoms of patients with PD. More importantly, patients did not experience significant side effects, such as constipation or sedation. Our study provides evidence that opioids can be used to treat pain symptoms in PD patients.