Loperamide: Uses, Dosage, Side Effects, and More
1. Drug Name
Generic Name: Loperamide
Brand Name(s):
- Pakistan: Imodium, Lopamide
- India: Imodium, Loperamide Hydrochloride
- United States: Imodium, Diamode
- United Kingdom: Imodium, Entrocalm
2. Pharmacological Class
Class: Antidiarrheal
Subclass: Opioid receptor agonist
3. Mechanism of Action
Loperamide works by binding to opioid receptors in the gut wall. This action inhibits the release of acetylcholine and prostaglandins, reducing peristalsis and increasing intestinal transit time. This leads to greater water absorption from the fecal material, thus firming the stool and reducing diarrhea.
4. Indications
Primary Indications:
- Acute diarrhea
- Chronic diarrhea associated with inflammatory bowel disease
- Traveler's diarrhea
Off-label Uses:
- Management of chronic diarrhea in patients with short bowel syndrome
5. Dosage and Administration
Standard Dosage:
- Acute Diarrhea: 4 mg initially, followed by 2 mg after each loose stool. Maximum: 16 mg/day.
- Chronic Diarrhea: Start with 4-8 mg daily in divided doses. Adjust according to response. Maximum: 16 mg/day.
Route of Administration: Oral
Special Populations:
- Pediatric: Not recommended for children under 2 years. For children over 2 years, dosage should be based on weight and age.
- Geriatric: No specific dose adjustment, but caution is advised due to potential for greater sensitivity to side effects.
6. Pharmacokinetics
Absorption: Poorly absorbed from the gastrointestinal tract.
Distribution: Limited systemic distribution due to poor absorption.
Metabolism: Extensively metabolized in the liver via cytochrome P450 enzymes.
Excretion: Primarily excreted in feces.
Half-life: Approximately 10.8 hours.
7. Contraindications
Loperamide is contraindicated in patients with:
- Hypersensitivity to loperamide or any of its components.
- Acute dysentery (blood in stools and high fever).
- Acute ulcerative colitis.
- Bacterial enterocolitis caused by invasive organisms.
- Pseudomembranous colitis associated with the use of broad-spectrum antibiotics.
8. Warnings and Precautions
Use caution in patients with:
- Liver impairment (due to extensive first-pass metabolism).
- Dehydration and electrolyte imbalance.
- Risk of constipation, especially in elderly patients.
Do not exceed recommended doses as high doses can lead to severe cardiac events including QT interval prolongation and ventricular arrhythmias.
9. Side Effects
Common Side Effects:
- Constipation
- Dizziness
- Nausea
- Abdominal cramps
Serious Side Effects:
- Severe allergic reactions (anaphylaxis)
- Paralytic ileus
- Severe constipation
- Cardiac arrhythmias (at high doses)
10. Drug Interactions
Major Interactions:
- Quinidine (increased loperamide levels)
- Ritonavir (increased loperamide levels)
Moderate Interactions:
- Itraconazole (increased risk of cardiac side effects)
- Ketoconazole (increased risk of cardiac side effects)
Minor Interactions:
- Saquinavir (reduced efficacy of saquinavir)
11. Pregnancy and Lactation
Pregnancy Category: C
Breastfeeding Considerations: Loperamide is excreted in breast milk in small amounts. Use only if clearly needed and the benefits outweigh the risks.
12. Patient Counseling Information
Key Points for Patients:
- Take loperamide exactly as directed by your healthcare provider.
- Do not exceed the recommended dose as it can lead to severe heart problems.
- Stay hydrated and maintain electrolyte balance while treating diarrhea.
- Report any severe abdominal pain, swelling, or constipation to your healthcare