What is Relistor?

Commonly Used Brand Name(s)Relistor

Therapeutic ClassificationsGastrointestinal Agent

Pharmacologic ClassificationsOpioid Antagonist

OverviewTOP

Methylnaltrexone injection is used to treat constipation caused by opioids (narcotic pain medicines), in adults with long-lasting pain that is not caused by cancer, or in patients with long-lasting pain caused by a previous cancer or its treatment who do not need weekly increases in opioid dosage. It is also used to treat constipation caused by opioids in adults with an advanced illness or cancer who need an increase in their opioid dosage.

This medicine is available only with your doctor's prescription.

Proper UseTOP

Your doctor will prescribe your exact dose and tell you how often this medicine should be given. It is given as a shot under your skin (usually in the upper arm, abdomen or stomach, or thighs) each day for long-lasting pain not caused by cancer or every other day for patients with an advanced illness.

Methylnaltrexone injection may be given at home to patients who do not need to be in the hospital. If you are using this medicine at home, your doctor will teach you how to prepare and inject the medicine. Be sure that you understand exactly how the medicine is prepared and injected.

This medicine comes with a Medication Guide and patient instructions. Read and follow these instructions carefully. Ask your doctor if you have any questions.

This medicine is available in three forms: a pre-filled syringe, a vial (glass container), or a vial and syringe with a retractable needle. You can use these dosage forms at home.

You will be shown the body areas where this shot can be given. Use a different body area each time you give yourself a shot. Keep track of where you give each shot to make sure you change body areas. This will help prevent skin problems from the injections. Do not inject into skin areas that are bruised, red, tender, hard, or have scars or stretch marks.

Use a new needle and syringe each time you inject your medicine.

You might not use all of the medicine in each vial (glass container). Use each vial or syringe only one time. Do not save an open vial or syringe. If the medicine in the vial or syringe has changed color, or if you see particles in it, do not use it.

Stop taking other laxatives before starting treatment with methylnaltrexone. You should also stop using this medicine if you have stopped taking narcotic pain medicines.

DosingTOP

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For injection dosage form:
- For constipation caused by opioids in patients with long-lasting non-cancer pain:
  - Adults—Dose is based on body weight and must be determined by your doctor. The dose is 12 milligrams (mg) injected under the skin once a day for at least 4 weeks (with narcotic pain medicines).
  - Children—Use and dose must be determined by your doctor.
- For constipation caused by opioids in patients with severe illness:
  - Adults weighing more than 114 kilograms (kg)—Dose is based on body weight and must be determined by your doctor. The dose is 0.15 milligram (mg) per kilogram (kg) of body weight injected under the skin every other day for 4 months.
  - Adults weighing 62 to 114 kg—Dose is based on body weight and must be determined by your doctor. The dose is usually 12 mg injected under the skin every other day for 4 months.
  - Adults weighing 38 to less than 62 kg—Dose is based on body weight and must be determined by your doctor. The dose is usually 8 mg injected under the skin every other day for 4 months.
  - Adults weighing less than 38 kg—Dose is based on body weight and must be determined by your doctor. The dose is 0.15 mg per kg of body weight injected under the skin every other day for 4 months.
  - Children—Use and dose must be determined by your doctor.

Missed DoseTOP

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Use & StorageTOP

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Store unopened vials of this medicine at room temperature, away from heat and direct light. Do not freeze. An open vial of this medicine must be used right away.

Throw away used needles in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.

Before UsingTOP

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

AllergiesTOP

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

PediatricTOP

Appropriate studies have not been performed on the relationship of age to the effects of methylnaltrexone injection in the pediatric population. Safety and efficacy have not been established.

GeriatricTOP

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of methylnaltrexone injection in the elderly.

PregnancyTOP

	Pregnancy Category	Explanation
All Trimesters	C	Animal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.

Breast FeedingTOP

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug InteractionsTOP

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

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.

Morphine
Morphine Sulfate Liposome
Naldemedine
Naloxegol
Oxycodone
Oxymorphone

Other InteractionsTOP

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

PrecautionsTOP

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to use it.

This medicine may cause a tear (perforation) in your stomach or bowels. Check with your doctor right away if you have a severe stomach pain that does not go away.

If severe or persistent (non-stop) diarrhea occurs while using methylnaltrexone injection, check with your doctor right away.

Do not suddenly stop using this medicine without checking first with your doctor. Doing so may cause withdrawal symptoms, such as anxiety, chills, increased tearing, redness on the face, neck, arms, and upper chest, feeling cold, diarrhea, irritability, stomach pain, sweating, and yawning.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.