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
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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; increases risk for GI perforation

Cautions

Severe renal impairment

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

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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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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.
  • Manage and view all your plans together – even plans in different states.
  • Compare formulary status to other drugs in the same class.
  • Access your plan list on any device – mobile or desktop.

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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