A Randomised Placebo Controlled Study of OXN PR for Severe Parkinson's Disease Associated Pain

Pain management in PD is a recognised unmet need. Estimates of incidence vary in the literature from 29% to 83%. The types and sources of pain experienced by PD patients vary and include: musculoskeletal pain, PD related chronic pain, fluctuation-related pain, nocturnal pain, coat-hanger pain, oro-facial pain and peripheral limb or abdominal pain (also including drug-induced pain). Whilst modifications to dosing of dopaminergic therapy represents the most common method of controlling some of these pain symptoms, this must be balanced against the worsening of side effects of increased doses of this treatment type.

Oxycodone hydrochloride and naloxone hydrochloride dihydrate combined oral prolonged release tablets (OXN PR), is the investigational product to be used in this study. OXN PR is a prolonged release tablet consisting of oxycodone and naloxone in a 2:1 ratio. Due to the local competitive antagonism of the opioid receptor-mediated oxycodone effect by naloxone in the gut, naloxone reduces opioid-associated bowel dysfunction.

The purpose of this study is to investigate whether effective pain control for the treatment of PD associated pain may be achieved with OXN PR. The secondary considerations for this study are to examine whether OXN PR may offer any additional benefits to the patients Quality of Life or symptoms of PD. If effective pain relief can be achieved with an analgesic without the side effects described in above, this could reduce the need to increase the dose of dopaminergic medications to manage pain, and therefore reduce the negative side effects of dopaminergic therapy described above. Given the prevalence of constipation in this patient population the bowel sparing effects of the OXN PR combination treatment may provide an ethical rationale for its use over that of other opioids.