1 What is Relistor?

Brand: Relistor

Generic: Methylnaltrexone

Relistor is used in the treatment of constipation caused by opioids in some patients. It decreases opioids effects in stomach and bowel which helps in relieving constipation.

It is used when other constipation medicines have not worked well. It is available in the form of a solution, only with your doctor’s prescription.

2 What to Know Before Using

Your doctor will inform you of what you need to know before using Relistor.


Inform your doctor if you are allergic to any food, preservatives, dyes, or had an allergic reaction when you used this drug before.


There are no adequate studies done which prove Methylnaltrexone effects in children. Use it after consulting your doctor. However, safety and efficacy have not been established.


This medicine does not cause any different side effects or problem than it does in younger adults.


It is a category C drug. It is not safe in pregnancy. It may cause harm and abnormalities in an unborn baby.

Breast Feeding

There are no adequate studies which prove that Methylnaltrexone passes into breast milk. If you are using Methylnaltrexone while nursing, discuss it with your doctor for possible risk factors.

Drug Interactions

Methylnaltrexone may interact with other drugs. Your doctor should be informed of any other medicines which you are taking. He may want to change the dosage or drug. Some of them are listed below:

  • Buprenorphine
  • Morphine
  • Morphine Sulfate Liposome
  • Naloxegol
  • Oxycodone
  • Oxymorphone

Other Medical Problem

Several other conditions may reduce its effectiveness.

Make sure you inform your doctor of conditions such as:

  • Kidney problems
  • You are on dialysis
  • Crohn's disease
  • Diverticulitis
  • Stomach or bowel problems (nausea, vomiting, stomach pain or swelling, cancer, ulcer, ogilvie syndrome)
  • If you have a peritoneal (abdominal) catheter.

3 Proper Usage

Proper usage of Relistor requires strict adherence to your doctor’s orders. It is given as an injection into your skin usually in the upper arm, abdomen or stomach, or thighs by your doctor or any trained health professional.

If you are using it at home, use it exactly as your doctor directed. Read the medication guide carefully. Ask your pharmacist if you have any queries.

A health care provider will teach you how to use Methylnaltrexone and ensure that you understand the procedure properly.

While using it, follow the instructions properly. It can be injected at stomach area (abdomen), upper thigh and upper arm. Inject it into a different area of your body every time.

Remove the needle after each injection and dispose of it properly. Use a new needle every time. Methylnaltrexone should not be used, if it has changed its color, became cloudy or if any particles are visible in it.

Use each vial or syringe only one time. Do not save an open vial or syringe. Do not take any other laxatives while using this medicine.


It is different for different patients. Dosage mentioned below is an average dose. It is best to take each dose at equally spaced times a day and night. You must follow your doctor’s command.

Doses for constipation caused by opioids in patients with chronic non-cancer pain are following:

  • Adults: The dose is usually 12 milligrams (mg) injected under the skin once a day.

Doses for constipation caused by opioids in patients with severe illness are following,

Doses are based on body weight and must be determined by your doctor.

  • Adults weighing more than 114 kilograms (kg): The dose is 0.15 milligram (mg) per kilogram (kg) of body weight injected under the skin every other day.
  • Adults weighing 62 to 114 kg: The dose is usually 12 mg injected under the skin every other day.
  • Adults weighing 38 to less than 62 kg: The dose is usually 8 mg injected under the skin every other day.
  • Adults weighing less than 38 kg: The dose is usually 0.15 mg per kg of body weight injected under the skin every other day.
  • Doses in children are determined by your doctor.

Missed dose

If you miss a dose, take it as soon as you remember it. If it almost a time for your next dose skips the missed dose and continue your daily schedule. Do not double the dose.


Store it at room temperature. Keep it away from children.

4 Precautions to Take

Before using Relistor, there are some precautions you must take. Your doctor should check your daily progress at regular visits.

It may cause perforation (tear) in your stomach or bowels. Inform your doctor immediately if you have any stomach pain which does not relieve with pain medication.

Your doctor will gradually reduce the dose of this drug before stopping it completely.

If you stop it suddenly it may cause:

Inform your doctor immediately if you have severe, persistent diarrhea.

5 Potential Side Effects

As with many medications, there are several potential side effects associated with Relistor. Some people may experience none or minor side effects.

Consult with your doctor if they become problematic or frequent:

More common are:

Symptoms of overdose are:

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.

6 Related Clinical Trials