Relistor (methylnaltrexone) is a good oral or injectable option for treating constipation due to opioid pain medications, but it can cause opioid withdrawal symptoms and diarrhea, and is quite expensive if it's not covered by insurance.
Constipation due to opioid pain medications
Opioid medications cause constipation because they slow down movement in the intestines (gut). Relistor (methylnaltrexone) is an opioid antagonist, which means that it blocks the opioid receptors in the intestines so that you can go to the bathroom more easily.
Source: FDA
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
Chills
cold sweats
confusion
dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Improves your chances of having bowel movements while you're on opioid medications
Available in injection form if you're unable to take medications by mouth or if you have an advanced illness
Injection form works pretty quickly (about 4 hours)
Directly targets the receptors that are causing constipation
Usually reserved for more severe constipation, after you have tried other medications first
Oral form must be taken daily, cannot be used "as needed"
Abdominal pain, diarrhea, and nausea are fairly common side effects.
Brand-name only and may be very expensive
Relistor (methylnaltrexone) pills are only approved for people taking opioid medications for pain that's not due to cancer. If you are taking opioid medications for cancer-related pain, you'll need to use the injection form of Relistor (methylnaltrexone).
If you're using opioids for non-cancer-related pain, stop taking all laxatives before starting on Relistor (methylnaltrexone). You can start using laxatives again if you're still constipated after using this medication for 3 days. Let your provider know if you change your opioid dose, since you may be more likely to get side effects like diarrhea.
If you're using the pill form, take it with water on an empty stomach at least 30 minutes before breakfast. If you take Relistor (methylnaltrexone) with food, it won't absorb in your body or work as well.
If you're using the injection form, make sure that your provider or pharmacist has shown you the proper injection technique. You'll want to inject Relistor (methylnaltrexone) into the upper arm, abdomen (belly area), or thigh. Rotate injection sites so that you're not using the same spot over and over again. Afterwards, make sure to throw out your needle in an appropriate disposal container, not the trash.
If you're using the injection form, make sure you're near a toilet after taking Relistor (methylnaltrexone), since it can make you have a bowel movement pretty quickly.
Stop taking Relistor (methylnaltrexone) if you stop taking opioid medications. If you continue to have constipation after you stop taking opioids, you'll need to use something else to treat it because Relistor (methylnaltrexone) will no longer be helpful.
Talk to your provider if you are pregnant or planning to become pregnant. Relistor (methylnaltrexone) can cause opioid withdrawal, which can be stressful to you and your unborn baby.
Relistor (methylnaltrexone) is brand-name only and may be expensive, even if you have insurance. Talk to your provider or pharmacist to see if you are eligible for a savings coupon.
Relistor (methylnaltrexone) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: Gastrointestinal disease or inflammation
In some rare cases, Relistor (methylnaltrexone) can cause gastrointestinal injury, including a hole or tear in the stomach or intestines which can be life-threatening. If you already have gastrointestinal problems, such as cancer, ulcer, inflammation, or Crohn's disease, talk to your provider about the risks and benefits before starting Relistor (methylnaltrexone). If you experience worsening, severe abdominal pain that doesn't go away, stop taking Relistor (methylnaltrexone) and contact your provider right away.
Relistor (methylnaltrexone) can cause severe diarrhea that doesn't go away. This could cause you to become dehydrated, which could be very dangerous. If you have several loose, watery stools, stop taking Relistor (methylnaltrexone) and talk to your provider.
Relistor (methylnaltrexone) can cause opioid withdrawal symptoms (sweating, chills, diarrhea, abdominal pain, anxiety, irritability, and yawning). In some rare cases, you may also get less pain relief from opioid medications. Talk to your provider if you experience any withdrawal symptoms or if your pain medications aren't working as well anymore.
Pill form: Take 450 mg by mouth once daily in the morning.
Injection form: The typical dose is 12 mg injected subcutaneously (under the skin) once daily. If you are taking Relistor (methylnaltrexone) for advanced illness, the dose may be lower or higher depending on your weight, and can be taken every other day as needed for constipation (but use no more than 1 dose in a 24-hour period).
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Constipation due to opioid pain medications
Long-term constipation due to unclear cause (idiopathic)
Constipation due to opioids
Constipation due to irritiable bowel syndrome (IBS) in women 18 years or older
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