From the Guidelines
Methylnaltrexone can help with opioid-induced constipation caused by chronic tramadol use, and it should be considered when traditional laxatives have failed. Tramadol, like other opioids, causes constipation by binding to mu-opioid receptors in the gut, slowing intestinal motility and reducing secretions. Methylnaltrexone is a peripherally-acting mu-opioid receptor antagonist that specifically targets these receptors in the gastrointestinal tract without affecting pain control, as it doesn't cross the blood-brain barrier 1. It's typically administered as Relistor, available as subcutaneous injection (8 or 12 mg every other day) or tablets (450 mg once daily).
Some key points to consider when using methylnaltrexone for tramadol-induced constipation include:
- Methylnaltrexone has been shown to be effective in treating opioid-induced constipation in patients with advanced illness and those with non-cancer pain 1
- The medication can work quickly, often producing a bowel movement within 30 minutes to 4 hours of administration 1
- Side effects may include abdominal pain, nausea, diarrhea, and flatulence 1
- Methylnaltrexone should be used cautiously in patients with known or suspected gastrointestinal obstruction and is contraindicated in bowel obstruction 1
According to the American Gastroenterological Association, methylnaltrexone is a recommended treatment option for opioid-induced constipation when traditional laxatives have failed 1. The medication has been shown to be safe and effective in clinical trials, with a low risk of adverse effects 1.
In terms of dosing, methylnaltrexone is typically administered subcutaneously at a dose of 8 or 12 mg every other day, or as a tablet at a dose of 450 mg once daily 1. The frequency of administration can be increased if needed, but patients should be monitored closely for signs of adverse effects.
Overall, methylnaltrexone is a useful treatment option for patients with opioid-induced constipation caused by chronic tramadol use, and it should be considered when traditional laxatives have failed. Patients should be educated on the potential benefits and risks of the medication, and monitored closely for signs of adverse effects.
From the FDA Drug Label
12.1 Mechanism of Action Methylnaltrexone is a selective antagonist of opioid binding at the mu-opioid receptor. As a quaternary amine, the ability of methylnaltrexone to cross the blood-brain barrier is restricted This allows methylnaltrexone to function as a peripherally-acting mu-opioid receptor antagonist in tissues such as the gastrointestinal tract, thereby decreasing the constipating effects of opioids without impacting opioid-mediated analgesic effects on the central nervous system (CNS).
The FDA drug label does not specifically mention tramadol as an opioid for which methylnaltrexone is effective in treating opioid-induced constipation.
- Key points:
- Methylnaltrexone is a peripherally-acting mu-opioid receptor antagonist.
- It decreases the constipating effects of opioids in the gastrointestinal tract.
- The label does not provide direct information on its use with tramadol. Therefore, no conclusion can be drawn about the effectiveness of methylnaltrexone in treating opioid-induced constipation caused by chronic tramadol use 2.
From the Research
Methylnaltrexone and Opioid-Induced Constipation
- Methylnaltrexone is a peripherally acting mu-opioid receptor antagonist that has been shown to be effective in treating opioid-induced constipation (OIC) in patients with chronic nonmalignant pain 3, 4, 5, 6.
- The studies demonstrate that methylnaltrexone induces laxation in patients with long-term opioid use without affecting central analgesia or precipitation of opioid withdrawal 3, 4, 5, 6.
- The action of methylnaltrexone is dose dependent, and weight-related dosing appeared to be effective 3.
- Adverse events, most frequently abdominal cramping or nausea, were usually mild to moderate 3, 4, 5, 6.
Efficacy of Methylnaltrexone in Chronic Tramadol Use
- While the provided studies do not specifically mention tramadol, they do demonstrate the efficacy of methylnaltrexone in treating OIC in patients with chronic nonmalignant pain 3, 4, 5, 6.
- Tramadol is an opioid analgesic that can cause constipation as a side effect, and methylnaltrexone may be effective in treating this condition based on its mechanism of action 3, 4, 5, 6.
- However, it is essential to note that the studies provided do not directly address the use of methylnaltrexone in patients taking tramadol, and further research may be necessary to confirm its efficacy in this specific population.
Administration and Monitoring
- Methylnaltrexone can be administered subcutaneously every other day to patients suffering from chronic constipation due to opioid therapy for whom laxatives do not provide adequate relief of their symptoms 3.
- Patients receiving methylnaltrexone must be monitored, and the drug is contraindicated in patients with known or suspected mechanical intestinal stenosis 3.