Conditions: Chronic Pain Opioid Induced Constipation
Keywords: pain opioid constipation Subjects taking opioids for chronic non-cancer pain, who experience symptoms of opioid induced constipation
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 40
Healthy volunteers: no

Brief summary:
For many patients taking opioids for pain relief one of the most distressing side effects is constipation. Naloxone is effective in the reversal of the effects of opioids and is used following opioid overdose. If naloxone is given by mouth it would relieve the effects of constipation but as it goes into the blood stream very quickly, it would also reverse the effects of the opioid and therefore stop the pain relief. The aim of this study is to examine a slow release formulation of naloxone to see if is can reduce constipation without reducing the pain relieving effects of the opioid.

Detailed description:
Naloxone has been used for many years as an IV or IM injection for the reversal of opioid effects (following opioid overdose) and has been evaluated as an oral formulation to manage opioid-induced constipation. Immediate release oral naloxone preparations have however led to reversal of opioid effects and withdrawal. This has initiated the development of prolonged (slow release) naloxone preparations which prevent the systemic levels of naloxone reaching levels where the central opioid effects may be reversed. Naloxone has a high first pass metabolism (98%) and short half life (\~1hr).

The objectives of this trial are to identify the optimum dosage regime of Naloxone SR capsules based on tolerability level, to improve spontaneous bowel movement frequency, and relieve GI symptoms, in patients suffering with opioid induced constipation.

Arms:
arm 1: Placebo capsules once daily for three weeks then twice daily for three weeks. arm 2: Naloxone SR 2.5 mg capsules once daily for three weeks then twice daily for three weeks. arm 3: Naloxone SR 10 mg capsules once daily for three weeks then twice daily for three weeks. arm 4: Two Naloxone SR 10 mg capsules once daily for three weeks then twice daily for three weeks. arm 5: Naloxone SR 5 mg capsules once daily for three weeks then twice daily for three weeks.

Interventions: intervention 1: Naloxone SR 5 mg capsules intervention 2: Placebo intervention 3: Naloxone SR 10 mg capsules intervention 4: Naloxone SR 20mg capsules intervention 5: Naloxone SR 2.5 mg capsules
Intervention descriptions: intervention 1: None intervention 2: None intervention 3: None intervention 4: None intervention 5: None

Protocol document: