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Generic Name: methylnaltrexone (METh IL nal TREX own)
Brand Name: Relistor
What is methylnaltrexone?
Methylnaltrexone blocks the effects of opioid medication. An opioid is sometimes called a narcotic.
Methylnaltrexone reduces constipation caused by narcotic medicine. Methylnaltrexone works by preventing constipation without reducing the pain-relieving effects of the narcotic.
Methylnaltrexone is given to people who use narcotic medicine to treat severe chronic pain. This medicine is not for use in people with pain caused by cancer.
Methylnaltrexone is usually given after laxatives have been tried without successful treatment of constipation.
Methylnaltrexone may also be used for purposes not listed in this medication guide.
What is the most important information I should know about methylnaltrexone?
You should not use this medicine if you have a blockage in your stomach or intestines.
What should I discuss with my health care provider before receiving methylnaltrexone?
You should not use methylnaltrexone if you are allergic to it, or if you have:
a blockage in your stomach or intestines.
To make sure methylnaltrexone is safe for you, tell your doctor if you have:
a stomach ulcer;
history of perforation (a hole or tear) in stomach or intestines;
colitis or other intestinal disorder; or
Methylnaltrexone may cause harm to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.
It is not known whether methylnaltrexone passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.
Methylnaltrexone is not approved for use by anyone younger than 18 years old.
How is methylnaltrexone used?
Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.
Methylnaltrexone is injected under the skin. You may be shown how to use injections at home. Do not self inject this medicine if you do not understand how to give the injection and properly dispose of used needles and syringes.
Methylnaltrexone can produce a bowel movement within 30 minutes. This medicine is given daily or every other day. Do not use methylnaltrexone more often than once every 24 hours.
Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions.
Prepare your dose only when you are ready to give an injection. After loading a syringe, keep it at room temperature protected from light and use it within 24 hours.
Methylnaltrexone should look clear or slightly yellow in color. Do not use the medication if it has changed colors or has particles in it. Call your doctor for a new prescription.
Your care provider will show you the best places on your body to inject methylnaltrexone. Use a different place each time you give an injection. Do not inject into the same place two times in a row.
Each single use vial (bottle) of this medicine is for one use only. Throw away after one use, even if there is still some medicine left in it after injecting your dose.
Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.
Call your doctor if your symptoms do not improve after 3 days of treatment.
After you stop using your pain medication, you should also stop using methylnaltrexone.
Store at room temperature away from moisture, heat, and light. Do not freeze.
What happens if I miss a dose?
Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.
Do not use this medicine more than once in a 24-hour period.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
When you have an opioid medication in your system, an overdose of methylnaltrexone could stimulate opioid withdrawal symptoms. Common withdrawal symptoms are yawning, irritability, sweating, chills, vomiting, diarrhea, and body aches.
What should I avoid while using methylnaltrexone?
Do not use any other laxatives that your doctor has not prescribed.
Methylnaltrexone side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using methylnaltrexone and call your doctor at once if you have:
severe stomach pain that gets worse or will not go away;
severe or ongoing diarrhea;
extreme dizziness, or feeling like you might pass out;
bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;
nausea or vomiting that are new or worsening symptoms; or
symptoms of narcotic medicine withdrawal--anxiety, sweating, chills, yawning, stomach pain, diarrhea.
Common side effects may include:
stomach pain, gas;
mild nausea or diarrhea;
dizziness, tremors; or
chills, sweating, or hot flashes.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Methylnaltrexone dosing information
Usual Adult Dose for Constipation -- Chronic:
Opioid-Induced Constipation in Patients with Chronic Non-Cancer Pain:
12 mg subcutaneously once a day
Comments: Prior to initiation, discontinue all maintenance laxative therapy; laxatives can be used as needed for suboptimal response after 3 days.
Opioid-Induced Constipation in Patients with Advanced Illness:
-One-dose subcutaneously every other day as needed, but no more frequently than 1 dose in a 24-hour period; weight-based dosing as follows:
Less than 38 kg: 0.15 mg/kg
38 kg to less than 62 kg: 8 mg (0.4 mL)
62 kg to 114 kg: 12 mg subcutaneously (0.6 mL)
More than 114 kg: 0.15 mg/kg subcutaneously
Comments: To determine injection volume for patients whose weight is less than 38 kg or more than 114 kg: multiply patient weight (kg) by 0.0075 and round up to the nearest 0.1 mL
-For the treatment of opioid-induced constipation in adult patients with chronic non-cancer pain.
-For the treatment of opioid-induced constipation in adult patients with advanced illness who are receiving palliative care, when response to laxative therapy has not been sufficient.
What other drugs will affect methylnaltrexone?
Other drugs may interact with methylnaltrexone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2012 Cerner Multum, Inc. Version: 5.03.
Last reviewed: August 17, 2015
Date modified: October 14, 2016