Overview
Loperamide is a widely used antidiarrheal medication that helps to slow down the movement of the gut. It is effectively used to control acute episodes of diarrhoea and manage chronic diarrhoea in conditions like inflammatory bowel disease.

Mechanism of Action
It acts directly on the opioid receptors in the intestinal wall, inhibiting the release of acetylcholine and prostaglandins. This decreases peristalsis, increasing intestinal transit time and allowing for more water absorption from the faecal matter.

Dosage and Administration
For acute diarrhoea in adults, the initial dose is typically 4 mg, followed by 2 mg after each unformed stool. The daily dose should not exceed 16 mg (prescription) or 8 mg (over-the-counter).

Side Effects
Generally well-tolerated. Common side effects include constipation, dizziness, nausea, and abdominal cramps. High doses can lead to serious cardiac arrhythmias.

Contraindications
Contraindicated in patients with dysentery (bloody stools and high fever), acute ulcerative colitis, or bacterial enterocolitis caused by invasive organisms.

Pregnancy and Lactation
Category C; it should be used during pregnancy only if the potential benefit justifies the risk. Small amounts appear in breast milk, so it is not recommended during breastfeeding.