Loperamide

1. Introduction

Loperamide is an anti-diarrhoeal medication that works by slowing intestinal motility through its action on the mu-opioid receptors in the gut. It reduces stool frequency and volume while improving stool consistency without affecting central nervous system activity.

2. Indications

  • Approved Indications:
    • Acute diarrhoea.
    • Chronic diarrhoea associated with irritable bowel syndrome (IBS).
    • Diarrhoea due to inflammatory bowel disease (adjunctive therapy).
    • Reduction of stool output in patients with ileostomy.
  • Off-Label Uses:
    • Traveller’s diarrhoea (mild cases).

3. Dosage

  • Adults:
    • Acute Diarrhoea:
      • Initial dose: 4 mg (2 tablets), followed by 2 mg after each loose stool.
      • Maximum dose: 16 mg/day (8 tablets).
    • Chronic Diarrhoea:
      • Initial dose: 4 mg/day, adjusted based on response.
      • Usual maintenance dose: 2–12 mg/day.
  • Children (≥6 years):
    • Acute Diarrhoea:
      • 2 mg after the first loose stool, then 1 mg per subsequent loose stool.
      • Maximum daily dose varies by weight and age (consult packaging or specialist).
  • Elderly:
    • No dose adjustment is necessary, but monitor for side effects.

4. Administration

  • Take orally with water.
  • Tablets should be swallowed whole.
  • For oral solution or chewable tablets, follow the manufacturer’s instructions.

5. Forms Available

  • Tablets: 2 mg.
  • Capsules: 2 mg.
  • Oral solution: 1 mg/5 mL.

6. Side Effects

6.1. Common Side Effects

  • Constipation.
  • Abdominal cramps.
  • Dizziness.

6.2. Less Common Side Effects

  • Nausea.
  • Dry mouth.
  • Flatulence.

6.3. Rare but Serious Side Effects

  • Toxic megacolon (especially in patients with inflammatory bowel disease).
  • Severe constipation or ileus.
  • Allergic reactions (e.g., rash, swelling, difficulty breathing).
  • Cardiac arrhythmias (at excessive doses).

7. Warnings

  • Severe Diarrhoea: Avoid use if diarrhoea is associated with blood in stools or high fever, as it may mask underlying infections.
  • Cardiac Risks: High doses may cause QT prolongation, torsades de pointes, or sudden cardiac death.
  • Toxic Megacolon: Use cautiously in patients with inflammatory bowel disease due to the risk of bowel obstruction.

8. Precautions

  • Avoid prolonged use in acute diarrhoea (no longer than 48 hours without consulting a doctor).
  • Do not use in children <6 years without medical advice.
  • Ensure adequate hydration and electrolyte replacement during diarrhoea treatment.

9. Interactions

  • Drug-Drug Interactions:
    • Ritonavir, quinidine: May increase loperamide levels, increasing the risk of side effects.
    • CNS depressants (e.g., alcohol): May enhance drowsiness or dizziness.
    • P-glycoprotein inhibitors (e.g., verapamil): Increased loperamide concentrations.
  • Drug-Food Interactions:
    • None significant; can be taken with or without food.

10. Monitoring Parameters

  • Frequency and consistency of stools.
  • Signs of dehydration (e.g., dry mouth, reduced urination).
  • Cardiac monitoring if high doses are used (e.g., ECG for QT prolongation).

11. Use in Children

  • Approved for children ≥6 years for acute diarrhoea but use cautiously.
  • Avoid in children <6 years due to increased risk of side effects and toxicity.

12. Use in Pregnancy

  • Category C: Use only if the potential benefits outweigh the risks. No evidence of harm in human studies, but data are limited.

13. Use in Elderly

  • Safe at standard doses, but monitor for constipation or dehydration.

14. Use in Kidney Disease

  • No dose adjustments are necessary, as loperamide is not significantly excreted by the kidneys.

15. Use in Liver Disease

  • Use cautiously in severe liver impairment, as loperamide is metabolised in the liver, increasing the risk of central nervous system side effects.

16. Patient Counselling Points

  • Take loperamide as directed and avoid exceeding the recommended dose.
  • Stay hydrated and consider oral rehydration solutions to replace lost fluids and electrolytes.
  • Do not use loperamide for diarrhoea with blood in stools or fever; consult a doctor instead.
  • Stop using and consult a doctor if diarrhoea persists for more than 48 hours or if constipation develops.
  • Report any symptoms of severe abdominal pain, swelling, or irregular heartbeat immediately.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
ImodiumJohnson & Johnson$5–10 (12 tablets, 2 mg)
Generic LoperamideVarious manufacturers$2–5 (12 tablets, 2 mg)

18. FAQs (15 Questions)

  1. What is loperamide used for?
    It is used to treat acute and chronic diarrhoea and reduce stool output in ileostomy patients.
  2. How does loperamide work?
    It slows bowel movements by acting on mu-opioid receptors in the gut, improving stool consistency and reducing frequency.
  3. How quickly does loperamide work?
    It usually starts working within 1–2 hours after taking the first dose.
  4. Can loperamide stop diarrhoea completely?
    It reduces diarrhoea but does not treat the underlying cause.
  5. What are common side effects of loperamide?
    Common side effects include constipation, abdominal cramps, and dizziness.
  6. Can loperamide be used for children?
    Yes, for children ≥6 years, but avoid use in younger children without medical advice.
  7. Is loperamide safe during pregnancy?
    It can be used if necessary, but consult your doctor first.
  8. Can I take loperamide for traveller’s diarrhoea?
    Yes, it is effective for mild traveller’s diarrhoea but avoid in cases of infection with blood in stools or fever.
  9. Can I drink alcohol while taking loperamide?
    Avoid alcohol, as it may increase dizziness or drowsiness.
  10. What should I do if I miss a dose of loperamide?
    Take it as soon as possible, but do not double the dose.
  11. How long can I take loperamide?
    Use for no longer than 48 hours without consulting a doctor.
  12. Can loperamide cause constipation?
    Yes, constipation is a common side effect, especially with prolonged use.
  13. Does loperamide treat the cause of diarrhoea?
    No, it only controls symptoms. Treating the underlying cause may require other medications.
  14. Can loperamide be taken with antibiotics?
    Yes, it is often used alongside antibiotics for bacterial diarrhoea, but consult your doctor first.
  15. How should loperamide be stored?
    Store at room temperature, away from light and moisture.