This medication is used to treat constipation caused by narcotic (opiate-type) medication. It blocks the effect of narcotics on the gut without blocking the effect on pain. It belongs to a class of medications called narcotic antagonists.
Read the Medication Guide and, if available, the Patient Information Leaflet provided by your pharmacist before you start using methylnaltrexone and each time you get a refill. If you have any questions, ask your doctor or pharmacist.
Inject this medication under the skin in the upper arm, abdomen, or thigh. Your doctor might direct you to use this medication once a day on a set schedule, or direct you to use it every other day as needed. Follow your doctor's instructions carefully. Do not use more than once in 24 hours. Do not inject into a muscle or vein.
If you are giving this medication to yourself at home, learn all preparation and usage instructions from your health care professional and the product package. The solution is normally clear and colorless to pale yellow. Before using, check this product visually for particles or discoloration. If either is present, do not use the liquid. Learn how to store and discard medical supplies safely.
Before injecting each dose, clean the injection site with rubbing alcohol. It is important to change the location of the injection site with each dose to avoid problem areas under the skin.
The dosage is based on your weight, medical condition, and response to treatment. Carefully check that you have drawn the correct dose into the syringe. The markings on the syringe measure the amount of liquid (milliliters/mL), not the amount of medication (milligrams/mg). For example, if your doctor has directed you to use 8 milligrams of medication, draw the liquid up to the 0.4-milliliter mark on the syringe. A 12-milligram dose is 0.6 milliliters. Ask your doctor or pharmacist if you have any questions or if you are not sure how to measure your dose.
This medication may be used with other laxatives. Ask your doctor if you should continue using your usual medications for constipation. This medication is used only for constipation caused by narcotics. Stop using methylnaltrexone when you stop taking narcotic pain medication unless otherwise directed by your doctor.
This medication works quickly. Most people have a bowel movement within a few minutes to a few hours after using this medication.
Tell your doctor if your condition persists or worsens. If you have severe or persistent diarrhea, stop using this medication and tell your doctor promptly.
Stomach/abdominal pain, nausea, gas, dizziness, fever, or diarrhea may occur. Pain, redness, or swelling at the injection site may also occur. If any of these effects persist or worsen, tell your doctor or pharmacist right away.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Stop using methylnaltrexone and tell your doctor right away if you have severe/persistent diarrhea.
Opiate withdrawal symptoms may occur in some people. Tell your doctor right away if any of these withdrawal symptoms occur: sweating, chills, abdominal cramps, diarrhea, mental/mood changes (such as anxiety, confusion, extreme sleepiness, visual hallucinations), yawning.
This drug may rarely cause a serious tear in the stomach or intestinal wall (perforation). If you notice any of the following unlikely but serious side effects, stop using this medication and get medical help right away: severe/persistent/worsening pain in the stomach/abdomen, fever, dizziness/fainting, nausea/vomiting.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Before using methylnaltrexone, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: stomach/bowel blockage (gastrointestinal obstruction), kidney disease, stomach/intestinal ulcers or tumors, bowel disease (such as Crohn's, diverticulitis).
This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.
To lower your risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
Before having surgery, tell your doctor or dentist that you are using this medication.
During pregnancy, this medication should be used only when clearly needed.
It is not known if this medication passes into breast milk. Consult your doctor before breast-feeding.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
If overdose is suspected, contact a poison control center or emergency room right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.
Do not share this medication with others.
For the best possible benefit, it is important to receive each scheduled dose of this medication as directed. If you miss a dose, contact your doctor or pharmacist right away to establish a new dosing schedule. Do not double the dose to catch up.
Store at room temperature away from light and moisture. Do not freeze. Do not store in the bathroom. Keep all medications away from children and pets.
If you have drawn the medication into the syringe but are not able to use it right away, you may store it at room temperature for 24 hours. Discard after 24 hours. Each vial is for a single use only. Discard any unused medication remaining in the vial after removing your dose.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised October 2015. Copyright(c) 2015 First Databank, Inc.
With WebMD's Medicine Cabinet, you can check interactions with drugs.Go to medicine cabinet