Anchor
μ-opioid receptor agonist (peripheral, non-CNS)

Loperamide

Imodium

How it works

Slows intestinal motility and increases fluid/electrolyte absorption. First-line rescue for irinotecan-induced and mFFX delayed diarrhoea.

Rescue medication for irinotecan / mFFX diarrhoea — every mFFX patient should have loperamide on hand from cycle 1. Fever + diarrhoea at any time is a medical emergency (neutropenic enterocolitis); call oncology or attend ED immediately.

Dosing

Typical doses

  • Standard: 4 mg at onset, then 2 mg every 4 h or after each loose stool (max 16 mg/day)
  • High-dose for irinotecan: 4 mg at onset, then 2 mg every 2 h until diarrhoea-free 12 h

Schedule

  • As needed
    prn

Side Effects

  • Constipation (rebound)
  • Abdominal cramping, distension
  • Toxic megacolon — rare but life-threatening; watch for distension, fever, ileus
  • Dehydration + electrolyte loss if diarrhoea severe (pre-loperamide risk)
  • QT prolongation / cardiotoxicity at very high unsupervised doses

Monitoring

  • Stool frequency + consistency; escalate to octreotide if Grade ≥3 diarrhoea > 24 h on loperamide + atropine-diphenoxylate
  • FBC — exclude neutropenic enterocolitis (febrile neutropenia + diarrhoea is an emergency)