II. Indications

  1. Severe refractory Constipation due to Opioids
    1. FDA approved for non-cancer, Opioid-Induced Constipation

III. Contraindications

  1. See Drug Interactions below (esp. CYP3A4 Inhibitors)
  2. Severe liver disease
  3. Bowel Obstruction

IV. Mechanism

  1. Block Opioid binding in the intestinal tract
  2. Decreases mu-Opioid receptor mediated bowel paralysis

V. Dosing: Adults

  1. General
    1. May crush tablet and give with water orally or via Nasogastric Tube
    2. Take on an empty Stomach >1 hour before OR 2 hours after first meal of the day
  2. Take 25 mg orally once daily in morning
  3. Indications for reduced dosing (12.5 mg)
    1. Renal Dosing: eGFR <60 ml/min
    2. Full dose not tolerated

VI. Adverse Effects

VII. Safety

  1. Pregnancy Category C
  2. Contraindicated in Lactation

VIII. Efficacy

  1. See Gastrointestinal Opioid Antagonist
  2. Best efficacy in those on Opioids for >4 weeks

IX. Drug Interactions

  1. Strong CYP3A4 Inhibitors (e.g. Clarithromycin, Ketoconazole)
  2. Strong CYP3A4 Inducers
  3. Grapefruit Juice
  4. Avoid with other opioid Antagonists
  5. Stop other Laxatives while taking Methylnaltrexone (may restart as needed in 3 days)

XI. References

  1. Hamilton (2020) Tarascon Pocket Pharmacopoeia
  2. (2023) Management of Constipation, Presc Lett, #390108

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Related Studies

Cost: Medications

movantik (on 1/1/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
MOVANTIK 12.5 MG TABLET $12.26 each
MOVANTIK 25 MG TABLET $12.30 each