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Clinician’s Corner: Opioid induced constipation


Numerous side effects are commonly seen with narcotic pain pills (opioids) use such as euphoria, respiratory depression, drowsiness, stomach upset and constipation. Of all the common side effects associated with narcotic use, the patient never develops a tolerance to constipation.  Opioid induced constipation (OIC) occurs in approximately 40% of patients treated with opioids.

  • Most feel that opioid constipation occurs if less than 3 bowel movements per week
  • OIC is dose related. As doses rise, OIC becomes more prevalent
  • Mechanism: opioids bind to receptors in the intestines inhibiting intestinal movements.


  • Stool softeners can result in “all mush, no push” simply because there’s not enough action in the bowels. Stool softeners are of little value for OIC.
  • For patients on opioids (hydrocodone, oxycodone, codeine etc.) recommend a stimulant laxative (senna or bisacodyl) to increase intestinal movement plus docusate if the stool is too hard to pass.
  • OTC Polyethylene Glycol 3350 (MiraLAX) is another excellent choice.

Prescription drugs for Opioid Induced Constipation

They all work by blocking the opioid receptors in the intestines but are unable to penetrate into the brain.  Therefore, they have no effect on the pain relieving abilities of the opioid

Methylnaltrexone: Selective Opioid Antagonist (Relistor®)

  • Indication: Treatment of opioid-induced constipation in patients with advanced illness who are receiving palliative care, when response to laxative therapy has not been sufficient.
  • Warnings/Precautions/Adverse Effects:
  • Contraindicated if known or suspected mechanical gastrointestinal obstruction
  • Discontinue therapy if severe or persistent diarrhea occurs
  • Use with caution in patients with known or suspected lesions of the GI tract
  • May cause gastrointestinal perforation (serious adverse effect)
  • May cause excessive sweating, abdominal pain, gas, nausea, dizziness (common adverse effects)
  • Effects can be seen within 4 hours of administration

Relistor® (methylnaltrexone) injection dosage: cost around $125 for 12mg vial

 Injection is based on body weight. Typical dose is 12mg SC once a day for chronic non-cancer pain.

Relistor 150mg (ORAL)  tablets    cost: $1635.00/month

Dose: 3 x150mg tablets  (450mg)  daily in the morning half hour before first meal of day

Naloxegol (Movantik®)   cost: $314/month

Dose:   25mg once daily; if not tolerated reduce to 12.5mg daily.  Us lower dose if reduced kidney function. Take on empty stomach, one hour before a meal or 2-3 hours after a meal.

Drug interactions: Avoid grapefruit juice. Be sure to check with your Thompson Pharmacist to check for drug interactions.

STOP all maintenance laxatives before starting Naloxegol, may restart in 3 days if not effective.

  • effective in people who have taken opioid pain medicines for at least 4 weeks
  • if opioid is stopped, stop Movantik®

Naldemedine (Symproic®)   cost: $314/month

Dose: 0.2mg tablet once daily, any time of day, with or without food.

Drug interactions: Avoid grapefruit juice. Be sure to check with your Thompson Pharmacist to check for drug interactions.

Prescription medications for treatment of OIC

  • Methylnaltrexone (Relistor) 12mg SC daily (chronic non-cancer pain)
    • Relistor 150mg tablets 3 tablets in the morning
  • Naloxegol (Movantik) 25mg orally in the morning
  • Naldemedine (Symproic) 0.2mg tablet orally daily in the morning
  • Lubiprostone (Amitiza) 24mcg orally twice daily (see last week’s newsletter)