Conditions: Neoplasms Constipation Opioid-Related Disorders
Keywords: Methylnaltrexone Constipation Narcotic Antagonists Analgesics, Opioid Neoplasms
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 12
Healthy volunteers: no

Brief summary:
The purpose of this study is to evaluate the efficacy of methylnaltrexone in relieving opioid-induced constipation in cancer patients at various stages of disease.

Detailed description:
Pain is one of the most common and important symptoms of cancer, often requiring opioid analgesics for control. However constipation is one of the most frequent and debilitating side effects of opioids, occurring in 40%-70% of patients being treated for chronic pain. Although laxatives are commonly used to manage opioid-induced constipation, these agents are not always effective or satisfactory. Methylnaltrexone bromide is a peripherally acting antagonist of the mu-opioid receptor. As a quaternary amine, the ability of methylnaltrexone to cross the blood-brain barrier is limited. This allows methylnaltrexone to function as a peripherally-acting antagonist in the gastrointestinal tract without impacting opioid-mediated analgesic effects in the central nervous system. The efficacy and safety of methylnaltrexone in treating opioid-induced constipation in patients with advanced disease receiving palliative care has been demonstrated. However the efficacy of this agent has not been evaluated in more active patients who are earlier in their disease course. The present study will evaluate the efficacy and safety of methylnaltrexone for the relief of severe opioid-induced constipation in this population and will attempt to identify factors predictive of methylnaltrexone response.

Arms:
arm 1: A single dose of methylnaltrexone will be administered subcutaneously to eligible subjects based on weight at the study entry. Since we will include subjects at all stages of cancer management, administering this study drug is considered experimental. We will use the dose approved by FDA, i.e., 0.15 mg/kg (round dose up to nearest 0.1 mL of volume) for weight less than 38 kg or greater than 114 kg; 8 mg (0.4 mL) for weight 38 kg to less than 62 kg; and 12 mg (0.6 mL) for weight 62 kg to 114 kg.

Interventions: intervention 1: Methylnaltrexone bromide
Intervention descriptions: intervention 1: Methylnaltrexone bromide, dosage based on weight (0.15 mg/kg (round dose up to nearest 0.1 mL of volume) for weight less than 38 kg or greater than 114 kg; 8 mg (0.4 mL) for weight 38 kg to less than 62 kg; and 12 mg (0.6 mL) for weight 62 kg to 114 kg), single dose

Protocol document: