Relistor (Methylnaltrexone bromide Oral)

Generic name:

Methylnaltrexone bromide

Drug class:

Peripherally acting μ-opioid receptor antagonist (PAMORA)

Dosage form:

• Oral tablets

Root of administration:

Oral

Dose:

• 12 mg once daily orally for adults with opioid-induced constipation
• Dosing may be adjusted based on clinical response and patient tolerability
• Varies by indication; consult label for specific patient populations (e.g., renal impairment)

Mechanism of action:

Methylnaltrexone bromide is a peripherally acting μ-opioid receptor antagonist that selectively blocks opioid receptors in the gastrointestinal tract without affecting central analgesia. It inhibits opioid binding on enteric neurons, thereby reversing opioid-induced decreased bowel motility and constipation.

Drug usage cases:

• Opioid-induced constipation (OIC) in adults with chronic non-cancer pain
• Opioid-induced constipation in patients with advanced illness receiving palliative care
• Constipation due to chronic opioid use when laxatives have failed to provide adequate relief
• Varies by indication; consult label

Drug contra indications:

• Known or suspected mechanical gastrointestinal obstruction
• Hypersensitivity to methylnaltrexone bromide or any components of the formulation
• Patients with known hypersensitivity to other PAMORAs
• Varies by indication; consult label

Side effects:

• Abdominal pain or cramps
• Diarrhea
• Nausea
• Flatulence
• Dizziness
• Headache
• Hyperhidrosis (excessive sweating)
• Gastrointestinal perforation (rare but serious)
• Injection site reactions (when applicable; primarily for non-oral forms)
• Varies by indication; consult label

Warnings:

• Risk of gastrointestinal perforation, particularly in patients with underlying conditions such as tumors, inflammation, or recent surgery
• Monitor for severe or persistent abdominal pain
• Do not use in patients with known or suspected mechanical bowel obstruction
• May cause opioid withdrawal symptoms if blood-brain barrier is compromised
• Use with caution in patients with cardiovascular disease
• Use in patients with hepatic or renal impairment requires careful dosing and monitoring
• Not established for use in pediatric patients
• Varies by indication; consult label

Use during pregnancy or breastfeeding:

There are no adequate and well-controlled studies of methylnaltrexone bromide in pregnant women. Animal reproduction studies have not shown direct or indirect harmful effects with respect to pregnancy or fetal development; however, the risk to humans is unknown. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It is unknown whether methylnaltrexone is excreted in human breast milk. Because many drugs are excreted in breast milk and due to the potential for adverse reactions on the nursing infant, a decision should be made whether to discontinue breastfeeding or to discontinue the drug, taking into account the importance of the drug to the mother.

Varies by indication; consult label.