Loperamide

An antidiarrheal agent that slows intestinal movement and reduces stool frequency.

What is Loperamide?

Loperamide is an opioid-receptor agonist that acts locally in the gut to treat acute and chronic diarrhea.

Unlike opioids, it does not produce pain relief or euphoria at normal doses.

History & Background

Loperamide was developed to provide effective diarrhea control without central nervous system opioid effects.

Chemical Structure & Properties

• IUPAC name: 4-(4-chlorophenyl)-4-hydroxy-N,N-diphenyl-1-piperidinebutyramide
• Molecular formula: C₂₉H₃₃ClN₂O₂
• Molar mass: 477.03 g/mol
• Functional groups: Piperidine, amide, aromatic rings

Mechanism of Action

Loperamide acts by stimulating μ-opioid receptors in the intestinal wall:

• Reduces intestinal motility
• Increases water absorption
• Decreases stool frequency

Pharmacokinetics

• Absorption: Poor systemic absorption
• Peak plasma time: 2.5–5 hours
• Metabolism: Liver (CYP3A4, CYP2C8)
• Half-life: 9–14 hours
• Excretion: Feces

Medical Uses

• Acute diarrhea
• Chronic diarrhea
• Traveler’s diarrhea
• Ileostomy output control

Dosage Guidelines

Adults: 4 mg initially, then 2 mg after each loose stool

Maximum: 16 mg/day (prescription)

⚠️ Do not exceed recommended dose.

Side Effects

• Constipation
• Abdominal cramps
• Dizziness
• Nausea

Warnings & Precautions

• Risk of serious cardiac arrhythmias with overdose
• Avoid in bloody or infectious diarrhea
• Stop if constipation or abdominal distension occurs

Drug Interactions

• Macrolide antibiotics
• Azole antifungals
• Other QT-prolonging drugs

Frequently Asked Questions

Is loperamide an opioid? – Yes, but acts only in the gut.

Can it cause addiction? – Only if abused.

Can children take it? – Only under medical advice.

Is it safe long-term? – Short-term preferred.

⚠️ Educational content only. Not a substitute for professional medical advice.