Methylnaltrexone
Class: GI Drugs, Miscellaneous
Chemical Name: (R)-N-(cyclopropylmethyl) noroxymorphone methobromide
Molecular Formula: C21H26NO4Br
CAS Number: 73232-52-7
Brands: Relistor
Introduction
Peripherally acting μ-opiate receptor antagonist; quaternary amine derivative of naltrexone.
Uses for Methylnaltrexone
Opiate-induced Constipation
Management of opiate-induced constipation in patients with advanced illness or pain caused by active cancer who require opiate dosage escalation for palliative care.
Management of opiate-induced constipation in patients with chronic non-cancer-related pain, including those with chronic pain related to prior cancer or its treatment who do not require frequent (e.g., weekly) increases in opiate dosage.
Methylnaltrexone Dosage and Administration
General
Discontinue methylnaltrexone if opiate therapy is discontinued.
Chronic Non-cancer-related Pain
Discontinue all maintenance laxative therapy prior to initiating methylnaltrexone; laxatives may be used as needed if the response to methylnaltrexone is suboptimal after 3 days.
Patients receiving opiates for <4 weeks may be less responsive to methylnaltrexone.
To avoid adverse effects (e.g., diarrhea), reevaluate continued need for methylnaltrexone if the opiate regimen is changed.
Administration
Administer orally or by sub-Q injection for management of opiate-induced constipation in patients with chronic non-cancer-related pain; administer by sub-Q injection in those with advanced illness.
Patient should be within close proximity to toilet facilities after methylnaltrexone is administered.
Oral Administration
Administer tablets with water on an empty stomach at least 30 minutes before the first meal of the day.
Sub-Q Administration
Administer by sub-Q injection into the upper arm, abdomen, or thigh. Use abdomen or thigh for self-administration; may use upper arm if not self-administered.
Rotate injection sites. Do not inject into areas where skin is bruised, tender, red, or hard, or where scars or stretch marks are present.
Use prefilled syringes only for patients who require an 8- or 12-mg dose; use single-use vial for all other doses.
Dosage
Available as methylnaltrexone bromide; dosage expressed in terms of the salt.
Adults
Opiate-induced Constipation in Patients with Advanced Illness
Sub-Q
Base dosage on patient’s weight (see Table 1). Give one dose every other day as needed. Do not exceed one dose per 24-hour period.
Determine injection volume by multiplying the patient’s weight in kg by 0.0075 and rounding up to nearest 0.1 mL.
Patient Weight (kg) | Injection Volume | Dosage (frequency of... MEDICAL DEPARTMENTS
Cardiology
Pediatrics
Diabetes Care
Pre-natal Care
Ultrasound Echocardiogram
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