Makindo Medical Notes

📖 About

• 💊 Anticholinergic burden (ACB) refers to the cumulative effect of drugs with antimuscarinic activity. Older adults are especially vulnerable because of reduced cholinergic reserve, polypharmacy, and impaired renal clearance.
• 📉 High ACB has been linked with cognitive decline, delirium, dizziness, falls, urinary retention, constipation, and increased hospitalisation. Some evidence even suggests long-term use may contribute to dementia risk.
• ⚠️ In UK primary care, up to one-third of older adults are prescribed ≥1 drug with anticholinergic properties.

🩺 Clinical Features of Anticholinergic Toxicity

Remember the classic medical rhyme: “Dry as a bone, blind as a bat, red as a beet, mad as a hatter, hot as a hare.” 🐇 This captures mucosal dryness, mydriasis, flushed skin, delirium, and fever from impaired sweating.

• 👄 Dry mouth, impaired swallowing, taste disturbance
• 🤢 Nausea, 💩 constipation, abdominal pain, paralytic ileus
• 🚽 Urinary hesitancy or retention — can precipitate acute kidney injury
• 👀 Blurred vision, photophobia, increased intraocular pressure
• ❤️ Tachycardia, palpitations
• 🧠 Neurological: agitation, confusion, hallucinations, delirium → seizures, coma

💊 Common Drug Classes with Anticholinergic Activity

• 📘 Tricyclic antidepressants — amitriptyline, imipramine
• 🌼 First-generation antihistamines — chlorpheniramine, diphenhydramine
• 🚻 Bladder antimuscarinics — oxybutynin, solifenacin, tolterodine
• 💉 Antipsychotics — chlorpromazine, haloperidol (weaker)
• 💊 Anti-Parkinson’s drugs — benzatropine, amantadine

🚫 Contraindications / High-Risk Conditions

• 👴 BPH – risk of urinary retention
• 👁️ Angle-closure glaucoma – can trigger acute crisis
• 💪 Myasthenia gravis – worsens neuromuscular weakness
• 🧠 Alzheimer’s / dementia – accelerates cognitive decline
• 🚫 Bowel obstruction or paralytic ileus
• 💧 Dehydrated/frail older adults – higher risk of delirium

📊 ACB Scoring Criteria

• 1️⃣ Score 1: In-vitro evidence of muscarinic antagonism, usually weak effect
• 2️⃣ Score 2: Clinical evidence or expert opinion of significant anticholinergic effects
• 3️⃣ Score 3: Strong evidence of causing delirium, high cognitive/functional risk

🔥 Examples of Score = 3 (Highest risk)

• Amitriptyline, Chlorpromazine
• Chlorpheniramine, Imipramine
• Solifenacin, Oxybutynin

⚠️ Examples of Score = 2

• Amantadine, Carbamazepine

ℹ️ Examples of Score = 1

• Aripiprazole, Atenolol, Cetirizine, Diazepam
• Digoxin, Dipyridamole, Disopyramide, Fentanyl
• Furosemide, Fluvoxamine, Haloperidol, Hydralazine
• Hydrocortisone, Isosorbide, Loperamide, Loratadine
• Metoprolol, Morphine, Nifedipine, Prednisone
• Quinidine, Ranitidine, Risperidone, Theophylline
• Trazodone, Triamterene, Venlafaxine, Warfarin

🧮 Practical Use

• 🧾 Use tools such as the Anticholinergic Cognitive Burden (ACB) scale in medication reviews.
• ⚖️ A total score ≥3 is associated with falls, hospitalisation and cognitive decline.
• 🔄 Always look for safer alternatives (e.g. SSRIs instead of TCAs for depression, second-generation antihistamines instead of sedating ones).
• 👨‍⚕️ Discuss deprescribing in MDT or GP medication reviews, especially in frail older adults.

💡 Teaching tip: Think about ACB whenever an older patient presents with new confusion or falls. The culprit is often hidden in a “harmless” drug like an antihistamine for hayfever or an oxybutynin patch for bladder urgency.