Study of Methylnaltrexone in Opioid-Induced Constipation Patients

Study Overview
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Brief Summary
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This is a multicenter, randomized, double-blind , placebo-controlled trail to investigate the safety and efficacy of subcutaneous methylnaltrexone for treating opioid-induced constipation in patients with advanced illness.

Detailed Description
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Methylnaltrexone is a quaternary derivative of the pure opioid antagonists naltrexone. It is fairly lipid soluble and readily cross the blood-brain barrier. This property provides methylnaltrexone with the potential to block the undesired side-effects of opioid pain medications predominantly mediated by receptors located peripherally while sparing opioid effects mediated at receptors in the central nervous system, most importantly analgesia. This is a multicenter, randomized, double-blind , placebo-controlled trail to investigate the safety and efficacy of subcutaneous methylnaltrexone for treating opioid-induced constipation in patients with advanced illness. The randomization schedule was used to assign patients in a 2:1 ratio to multicenter or an equal volume of placebo administered subcutaneously on alternate days for 2 weeks. The clinical trail was estimated to enroll 180 patients totally.

Official Title
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Methylnaltrexone (MNTX) for Treatment of Opioid-induced Constipation in Advanced Illness Patients : a Multicenter, Randomized, Double-blind , Placebo-controlled Trail

Conditions
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Opioid-induced Constipation

Intervention / Treatment
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* Drug: Methylnaltrexone (MNTX)
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: A life expectancy of 3 month or more Qualifying patients received opioids for analgesia for 1 week or more and a stable regimen of opioids and laxatives for 3 or more days before study entry Patients had opioid-induced constipation with either fewer than three laxation during the preceding week and no clinically meaningful laxation (as determined by the in investigator ) within 24h before the first study dose or no clinically meaningful laxation within 48h before the first study dose During the two-week trail , patients would keep their life habits (dietary fiber , fluid intake and physical activity) Patients volunteered for the trail Women of childbearing potential had negative pregnancy tests. Both male and female patients need to take effective contraceptives to avoid pregnancy. Exclusion Criteria: Constipation that was not primarily caused by opioids ( as determined by the investigator) Mechanical gastrointestinal obstruction, an indwelling peritoneal catheter, clinically active diverticular disease , fecal impaction , acute surgical abdomen , and fecal ostomy Patients had the surgery plan which would effect the results of pain assessment Patients had hypersensitivity to methylnaltrexone , naltrexone or naloxone or if any investigational drug or experimental product

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Drug<br>Methylnaltrexone (MNTX) nearly 0.15mg/kg administered every other day for 2 weeks. | Drug: Methylnaltrexone (MNTX)<br>* MNTX nearly 0.15mg/kg administered every other day for 2 weeks. Baseline laxatives and rescue laxative ( enemas/suppositories ) were allowed, but could not be administered within 4 hours of the study drug.<br>|
| Placebo Comparator: Placebo<br>Placebo administered every other day for 2 weeks. | Drug: Placebo<br>* Placebo administered every other day for 2 weeks. Baseline laxatives and rescue laxative ( enemas/suppositories ) were allowed, but could not be administered within 4 hours of the study drug.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The proportion of subjects who had the Rescue-free laxation response within 4 hours of the initial dose | Within 4 hours after the initial dose, if clinical significant bowel movement happened, the drug therapeutic effect was confirm. In the meantime, the time of bowel movement and other properties of bowel movement were recorded. The percentage of patients who had rescue-free laxation response is the primary outcome. | up to 4 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The proportion of subjects who had at least 2 Rescue-free laxation responses within 4 hours after each doses from the first dose to the forth dose | Record the frequency of laxation. After 1-4 dose, within 4 hours of every dose, record the dose number when bowel movement happened | up to 8 days | 
| The proportion of subjects who had Rescue-free laxation response within 4 hours after each doses from the second dose to the last dose |  | up to 12 days | 
| The proportion of subjects who had Rescue-free laxation response within 4-24h after each dose |  | up to 14 days | 
| The proportion of subjects who had ≥3 laxation responses per week |  | up to 2 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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opioid-induced constipation