methylnaltrexone (Rx)

Brand and Other Names:Relistor
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

injectable solution

  • 8mg/0.4mL vial
  • 12mg/0.6mL vial

tablet

  • 150mg

Opioid-Induced Constipation (Advanced Illness Receiving Palliative Care)

Indicated for the treatment of opioid-induced constipation (OIC) in patients with advanced illness who are receiving palliative care, when response to laxative therapy has been insufficient

38-62 kg: 8 mg/dose SC every other day  

62-114 kg: 12 mg/dose SC every other day

<38 kg or >114 kg: 0.15 mg/kg/dose SC every other day

Dosing considerations

  • Usual dose is every other day; not to exceed 1 dose/24 hr
  • Use beyond 4 months has not been studied in the advanced illness population

Opioid-Induced Constipation (Chronic Noncancer Pain)

Indicated for the treatment of opioid-induced constipation (OIC) in adult patients with chronic noncancer pain

12 mg SC qDay, OR

450 mg PO qDay in morning

Also see Administration

Dosage Modifications

Renal impairment

  • Mild: No dose adjustment recommended
  • Moderate-to-severe (CrCl <60 mL/min): Modified dosage shown by indication below according to indication and dosage form
  • OIC with chronic noncancer pain
    • Tablets: 150 mg PO qDay in morning
    • SC injection: 6 mg SC qDay
  • OIC with advanced illness receiving palliative care
    • Every other day SC injection based on weight
    • <38 kg: 0.075 mg/kg
    • 38 to <62 kg: 4 mg
    • 62-114 kg: 6 mg
    • >114 kg: 0.075 mg/kg

Hepatic impairment

  • Tablets
    • Mild (Child-Pugh A): No dose adjustment recommended
    • Moderate-to-severe (Child-Pugh B or C): 150 mg PO qDay in morning
  • SC injection
    • Every other day SC injection based on weight for severe hepatic impairment
    • <38 kg: 0.075 mg/kg
    • 38 to <62 kg: 4 mg
    • 62-114 kg: 6 mg
    • >114 kg: 0.075 mg/kg

Safety and efficacy not established

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Adverse Effects

>10%

Abdominal pain (28.5%)

Flatulence (13.5%)

Nausea (11.5%)

1-10%

Dizziness (7.3%)

Hyperhidrosis (6.7%)

Diarrhea (5.5%)

Postmarketing Reports

Gastrointestinal: Cramping, perforation, vomiting

General disorders and administrative site disorders: Diaphoresis, flushing, malaise, pain

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Warnings

Contraindications

Documented hypersensitivity

Known or suspected GI obstruction and patients at increased risk of recurrent obstruction

Cautions

Discontinue if severe/persistent diarrhea develops

GI perforation reported with other PAMORA in patients with conditions associated with reduced structural integrity in the wall of the GI tract (eg, PUD, Ogilvie syndrome, diverticular disease, infiltrative GI malignancies, peritoneal metastases, Crohn disease); monitor for development of severe, persistent, or worsening abdominal pain; discontinue naloxegol in patients who develop these symptoms

Symptoms consistent with opioid withdrawal (eg, hyperhidrosis, chills, diarrhea, abdominal pain, anxiety, irritability, yawning) reported; monitor for symptoms of withdrawal in such patients

Therapy administration for longer than four months not studied; discontinue therapy when opioid therapy has ended

Use with caution in hepatic or renal impairment; dosage adjustments necessary

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Pregnancy & Lactation

Pregnancy

The limited available data with in pregnant women are not sufficient to inform a drug-associated risk for major birth defects and miscarriages; there are clinical considerations when drug is used by pregnant women; advise pregnant women of potential risk to a fetus

Use during pregnancy may precipitate opioid withdrawal in a fetus due to immature fetal blood-brain barrier

Lactation

No information regarding presence of methylnaltrexone in human milk, effects on breastfed infant, or on milk production; methylnaltrexone is present in rat milk; because of potential for serious adverse reactions, including opioid withdrawal, in breastfed infants, advise women that breastfeeding is not recommended during treatment

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

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Pharmacology

Mechanism of Action

Peripheral mu-opioid receptor antagonist; limited ability to cross blood brain barrier so doesn't abolish opioid-induced analgesia nor cause withdrawal symptoms but decreases opioid-induced constipation

Absorption

Onset of action: Within 30-60 min

Peak plasma time: 0.5 hr

Peak plasma concentration: 117-392 ng/mL (dose dependent)

AUC: 175-582 ng·hr/mL (dose dependent)

Distribution

Protein bound: 11-15.3%

Vd: 1.1 L/kg

Metabolism

Metabolites: 5 distinct metabolite; methyl-6-naltrexol isomers (5% of total) and methylnaltrexone sulfate (1.3% of total) appear to be the primary pathways of metabolism

Elimination

Half-life elimination: 8 hr

Excretion: Urine (50%); feces (50%)

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Administration

General Information

Be within close proximity to toilet facilities when administered

Shown to be efficacious in patients who have taken opioids for at least 4 weeks

Discontinue all maintenance laxative therapy prior to initiation; laxatives can be used prn if there is suboptimal response to methylnaltrexone after 3 days

Reevaluate the continued need for methylnaltrexone when the opioid regimen is changed to avoid adverse reactions

Discontinue if the opioid pain medication is also discontinued

SC Administration

Administer in upper arm, abdomen, or thigh (rotate injection site)

Oral Administration

Take with water on an empty stomach at least 30 minutes before the first meal of the day

Storage

Tablets or injection: Store at controlled room temperature up to 25ºC (77ºF); excursions permitted to 15-30ºC (59-86ºF)

Injection: Do not freeze and protect from light

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Images

BRAND FORM. UNIT PRICE PILL IMAGE
Relistor subcutaneous
-
12 mg/0.6 mL solution
Relistor subcutaneous
-
12 mg/0.6 mL solution
Relistor subcutaneous
-
12 mg/0.6 mL vial
Relistor subcutaneous
-
8 mg/0.4 mL solution
Relistor oral
-
150 mg tablet

Copyright © 2010 First DataBank, Inc.

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Patient Handout

Patient Education
methylnaltrexone subcutaneous

METHYLNALTREXONE - INJECTION

(METH-il-nal-TREX-one)

COMMON BRAND NAME(S): Relistor

USES: This medication is used to treat constipation caused by opioid medication. It blocks the effect of opioids on the gut without blocking the effect on pain. Methylnaltrexone belongs to a class of medications known as opioid antagonists.

HOW TO USE: 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.Ask your doctor if you should continue using your usual medications for constipation. This medication is used only for constipation caused by opioids. Stop using methylnaltrexone when you stop using opioid pain medication unless otherwise directed by your doctor.Make sure you are close to a bathroom after using this medication. 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 lasts or gets worse.

SIDE EFFECTS: 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 lasts or gets worse, tell your doctor or pharmacist promptly.To lower your risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.Remember that this medication has been prescribed because your doctor 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 diarrhea that doesn't stop.Opioid 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). Stop using this medication and get medical help right away if any of these very serious side effects occur: severe stomach/abdominal pain that doesn't go away, fever, severe dizziness, fainting, severe 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.

PRECAUTIONS: 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/intestinal problems (such as blockage, ulcers, tumors, Crohn's disease, diverticulitis), kidney disease, liver disease.This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: 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.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center 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.

NOTES: Do not share this medication with others.

MISSED DOSE: It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule. Do not double the dose to catch up.

STORAGE: 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 August 2021. Copyright(c) 2021 First Databank, Inc.

IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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Formulary

FormularyPatient Discounts

Adding plans allows you to compare formulary status to other drugs in the same class.

To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

Adding plans allows you to:

  • View the formulary and any restrictions for each plan.
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The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

Tier Description
1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
NC NOT COVERED – Drugs that are not covered by the plan.
Code Definition
PA Prior Authorization
Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
QL Quantity Limits
Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
ST Step Therapy
Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
OR Other Restrictions
Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.