Pain is a fundamental symptom of Parkinson's disease (PD) that is often unrecognized and undertreated. This study was designed to evaluate the safety and efficacy of using opioids in patients with PD.

This eight week, single center, prospective, observational trial included 14 patients with PD and chronic pain syndromes. The participants were prescribed oxycodone hydrochloride, combined with naloxone hydrochloride dehydrate (OXN PR 5/325), beginning at once a day and titrated to twice per day after one week. Pain intensity was assessed by the 11-point Numeric Rating Scale (NRS) and the Brief Pain Inventory (BPI), motor status by the Unified Parkinson's Disease Rating Scale Section-III (UPDRS-III) and cognitive status by the Mini Mental State Examination (MMSE). In addition, the patients were assessed with the Global Impression of Change (CGI-C). All were followed with weekly examinations for eight weeks.

A significant reduction was seen in the NRS scores during the entire observation (ANOVA P<0.05). A 30% or greater reduction in the mean NRS scores was noted from baseline to eight weeks in 56% of the patients. The ratings were much improved for 42.86% of the patients. Bowel function was not worsened by the analgesic treatment, as demonstrated by changes in BFI scores.

This study of patients with Parkinson's disease found that a combination of oxycodone XR and naloxone may be a safe and effective treatment for chronic pain.