Methylnaltrexone (Subcutaneous)

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

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

It is very important for your doctor to check your progress at regular visits. This will help your doctor see if the medicine is working properly and decide if you should keep using it.

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

If you experience severe or persistent (non-stop) diarrhea while using methylnaltrexone injection, contact your doctor immediately.

Do not suddenly stop using this medicine without first checking with your doctor. Doing so may lead to 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 you have discussed them with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

In deciding to use a medicine, you and your doctor need to consider the risks and benefits. For this medicine, please think about the following:

Allergies

Inform your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also, let your healthcare professional know if you have any other allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, carefully read the label or package ingredients.

Pediatric

Studies have not been conducted to determine how age affects the effects of methylnaltrexone injection in children. Safety and effectiveness have not been established.

Geriatric

Current studies have not shown any specific problems in older adults that would limit the use of methylnaltrexone injection.

Breast Feeding

There are no sufficient studies in women to determine the risk to infants when using this medicine during breastfeeding. Consider the potential benefits and risks before taking this medication while breastfeeding.

Interactions with Medicines

Some medicines should not be used together at all, while in other cases, two different medicines may be used together even if an interaction might happen. In such cases, your doctor may adjust the dose or take other precautions. It is very important for your healthcare professional to know if you are taking any of the medicines listed below when you are using this medicine. The following interactions are based on 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 necessary in some situations. If both medicines are prescribed together, your doctor may adjust the dose or frequency of one or both medicines.

• Morphine
• Morphine Sulfate Liposome
• Naldemedine
• Naloxegol
• Oxycodone
• Oxymorphone

Interactions with Food/Tobacco/Alcohol

Some medicines should not be used around the time of eating certain foods because interactions may occur. Using alcohol or tobacco with certain medicines may also lead to interactions. Talk to your healthcare professional about using your medicine with food, alcohol, or tobacco.

Other Medical Problems

Having other medical problems may affect how you use this medicine. Make sure to tell your doctor if you have any other medical issues, especially:

• Crohn's disease or
• Diverticulitis or
• Ogilvie's syndrome (decreased movement of food in the intestines) or
• Peptic ulcer or
• Stomach or bowel cancer—This may increase the risk of more serious side effects.

• Liver disease or
• Severe kidney disease—Use cautiously. The effects may be stronger because the body may remove the medicine more slowly.

• Known, suspected, or increased risk of stomach or bowel blockage—This medicine should not be used in patients with these conditions.

Along with its necessary effects, a medicine may cause some unwanted effects. Not all of these side effects may happen, but if they do, they may need medical attention.

Check with your doctor right away if any of the following side effects occur:

More common

• Diarrhea
• increased sweating

Incidence not known

• Bloody, black, or tarry stools
• heartburn
• indigestion
• nausea
• severe abdominal or stomach pain, cramping, or burning
• trouble breathing
• vomiting material that looks like coffee grounds, severe and continuous

Get emergency help right away if any of the following overdose symptoms 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 happen that usually do not need medical attention. These side effects may go away during treatment as your body gets used to the medicine. Also, your health care professional may be able to tell you how 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:

More common

• Bloated
• dizziness
• excess air or gas in the stomach or intestines
• feeling of fullness
• passing gas
• stomach pain

Other side effects not listed may also happen in some patients. If you notice any other effects, check with your health care professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

In the U.S.

• Relistor

Available Dosage Forms:

• Solution

Therapeutic Class: Gastrointestinal Agent

Pharmacologic Class: Opioid Antagonist

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.

Dosing

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 Dose

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.

Storage

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.

• Which drugs cause opioid-induced constipation?