Methylnaltrexone

Scottish Palliative Care Guidelines
Healthcare Improvement Scotland
Red – For medicines normally initiated and used under specialist guidance

Introduction

A peripheral opioid antagonist used in palliative care for intractable opioid-induced constipation where response to usual laxative therapy has not been sufficient.

Preparations

  • Injection containing 20mg of methylnaltrexone bromide per ml.
  • Each vial of 0.6ml contains 12mg of methylnaltrexone bromide for subcutaneous (SC) injection.

 

Indications

May be recommended by a palliative care specialist for treatment of opioid-induced constipation in patients with advanced illness when optimum use of laxatives is ineffective.

 

Cautions

  • Known or suspected lesions of the gastrointestinal (GI) tract.
  • Diverticular disease; faecal impaction; patients with colostomy or peritoneal catheter.
  • Conditions which may predispose to perforation.
  • Dose reduction required in severe renal impairment. Avoid in patients in end stage renal impairment receiving dialysis and in severe hepatic impairment.
  • Assess risk versus benefit in pregnancy and breast feeding.

 

Contra-indications

  • Known or suspected mechanical GI obstruction or acute surgical abdomen.

 

Drug interactions

  • No clinically significant interactions identified.

 

Side effects

Common: abdominal pain/colic, diarrhoea, flatulence, nausea, dizziness (postural hypotension can occur).

Rare: syncope, severe diarrhoea, cardiovascular collapse, GI perforation.

 

Dose and administration

  • For patients weighing 38 to 61kg - 8mg SC (0.4ml of solution) on alternate days.
  • For patients weighing 62 to 114kg - 12mg SC (0.6ml of solution) on alternate days.
  • Outside this range give 150micrograms/kg on alternate days.
  • The interval between administrations may be varied but not more than once a day.

 

Practice points

  • Rotate injection sites.
  • Avoid hard or red areas and areas of tenderness or bruising.
  • Recommended injection sites are upper legs, abdomen and upper arms.
  • Treatment can result in the rapid onset of a bowel movement (within 30 to 60 minutes).
  • Treatment is added to usual laxative therapy which may subsequently require review.
  • If severe or persistent diarrhoea occurs during treatment, patients should be advised to discontinue therapy and consult their doctor.
  • Further information: Specialist Palliative Care services/Palliative Medicine on-call advice service.
  • Patient Information leaflet on the Electronic Medicines Compendium.

 

References

Palliative Care Formulary (PCF) on the Knowledge Network via Athens password (http://www.knowledge.scot.nhs.uk/home/portals-and-topics/palliative-care.aspx).

Summary of Product Characteristics (revised Feb 2017) on the Electronic Medicines Compendium at www.medicines.org.uk.

Product information on the European Medicines Agency website at http://www.ema.europa.eu.

Candy B et al. (2011) Laxatives or methylnaltrexone for the management of constipation in palliative care patients. Cochrane Database of Systematic Reviews. 19: CD003448.