Propantheline 💊

📖 About

Always check the BNF link here for the latest guidance.

⚙️ Mode of Action

• 🛑 Propantheline is an antimuscarinic agent (quaternary ammonium compound).
• Blocks muscarinic ACh receptors in the GI tract → ↓ smooth muscle spasm & ↓ secretions.
• 🚫 Poor CNS penetration (unlike tertiary amines e.g. oxybutynin) → fewer central side effects.

💊 Indications / Dose

• 🍽️ Irritable Bowel Syndrome (IBS) & Bowel Spasm: 15 mg TDS 1 hr before meals + 30 mg at night (max 120 mg/day).
• 🩺 Historically used in peptic ulcer disease (rare now due to PPIs).

🔄 Interactions

• ⚠️ Additive anticholinergic burden with: tricyclics, antihistamines, antipsychotics.

⚠️ Cautions

• 👵 Elderly: higher risk of confusion, constipation, urinary retention.
• 🧠 Use with caution in autonomic neuropathy.
• 💩 Can mask underlying pathology in diarrhoea.

⛔ Contraindications

• 💪 Myasthenia gravis.
• 🚫 Paralytic ileus, pyloric stenosis.
• 👁️ Untreated angle-closure glaucoma.

🤒 Side Effects

• 👄 Dry mouth, 👓 blurred vision, 🚽 constipation, 💧 urinary retention.
• ❤️ Tachycardia, flushing.
• 🧠 CNS: dizziness/confusion (less frequent than tertiary amines).

🧠 Teaching Pearls

💡 Propantheline is quaternary → poor CNS penetration → fewer central side effects (contrast with oxybutynin, a tertiary amine that often causes drowsiness/confusion).
💡 Exam tip: In IBS with troublesome cramping, propantheline or hyoscine butylbromide may be used for short-term symptom relief, but long-term benefit is limited.

📚 References

• BNF: Propantheline
• Katzung BG. Basic & Clinical Pharmacology, 15th Edition.