Gastrointestinal Opioid Antagonist

Aka: Gastrointestinal Opioid Antagonist, Peripheral Acting Mu-Opioid Receptor Antagonist, PAMORA, Methylnaltrexone, Relistor, Movantik, Naloxegol, Symproic, Naldemedine, Alvimopan, Entereg

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II. Indications

  1. Severe refractory Constipation due to Opioids

III. Mechanism

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

IV. Preparations

  1. Naloxegol (Movantik) once daily orally in morning ($10/day)
    1. FDA approved for non-cancer, Opioid-Induced Constipation
    2. Requires Renal Dosing adjustment
    3. Chey (2014) N Engl J Med 370:2387-96 [PubMed]
  2. Methylnaltrexone (Relistor) injection ($70/day)
    1. Methylnaltrexone 5 mg or 0.15 mg/kg SQ
    2. Weight-based SQ Injection once or twice daily
    3. Diarrhea occurs in 8% and Abdominal Pain in 13%
    4. Requires Renal Dosing adjustment
    5. Contraindicated in Intestinal Obstruction
    6. Exercise caution in intestinal malignancy
  3. Naldemedine (Symproic)
    1. Dose: Orally once daily
    2. No renal dose adjustment needed
  4. Alvimopan (Entereg)
    1. Approved only for short-term management of post-operative ileus
    2. Restricted prescribing due to risk of Myocardial Infarction

V. Advantages

  1. Does not cross blood-brain barrier

VI. Disadvantages

  1. All agents in this class are expensive as of 2017 (costs range between $10 to $70 per day)

VII. Efficacy

  1. In general, results in one more Bowel Movement per week and may spare Laxative use
  2. Refractory Opioid Induced Constipation in Cancer and Palliative Care
    1. Both oral Naldemedine (Symproic) and SQ Methylnaltrexone (Relistor) are effective with benefits outweighing harms
    2. Brown (2023) Am Fam Physician 107(2):131-2 [PubMed]
  3. Terminally ill patients
    1. Bowel Movement occurs within 4 hours of dose in 48% of patients (15% wiith Placebo)
    2. Median time to Bowel Movement is 45 minutes (>6 hours for Placebo)

VIII. References

  1. (2017) Presc Lett 24(12): 70
  2. Portenoy (2008) J Pain Symptom Manage 35(5): 458-68 [PubMed]
  3. Thomas (2008) N Engl J Med 358(22): 2332-43 [PubMed]

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Related Studies

Cost: Medications

relistor (on 1/1/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
RELISTOR 12 MG/0.6 ML SYRINGE $232.20 per ml
RELISTOR 12 MG/0.6 ML VIAL $230.56 per ml
RELISTOR 150 MG TABLET $23.17 each
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
symproic (on 1/1/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
SYMPROIC 0.2 MG TABLET $13.31 each
FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information. GoodRx is another tool for finding lower drug prices.

Related Topics in Pharmacology

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