1 · Overview
Atropine, hyoscyamine and scopolamine are tropane alkaloids concentrated in plants of the Solanaceae family—most notably Atropa belladonna (deadly nightshade) and Datura stramonium (jimson-weed). These compounds act as potent competitive antagonists at muscarinic acetylcholine receptors, producing the classic “anticholinergic toxidrome.” Untreated, severe poisoning may culminate in seizures, hyperthermia, rhabdomyolysis, dysrhythmia or respiratory failure [1] [2].
2 · Causes & Modes of Exposure
- Accidental ingestion of attractive belladonna berries by children or misidentified wild greens mixed with edible plants [1] [6].
- Recreational consumption of Datura seeds, teas or smoked leaves for their hallucinogenic effect; alkaloid content is unpredictable and easily leads to overdose [1].
- Medication error—excess parenteral or ophthalmic atropine during medical treatment, especially in paediatrics or anaesthesia [1].
- Unregulated herbal products containing belladonna alkaloids in mislabeled doses [1].
3 · Pathophysiology
Tropane alkaloids freely cross the blood-brain barrier and reversibly block M1-3 receptors in peripheral organs and the CNS. The loss of parasympathetic tone yields:
- Peripheral effects: anhidrosis → hyperthermia; tachycardia; mydriasis; urinary retention; ileus.
- Central effects: agitation, vivid visual hallucinations, disorientation, delirium and, with high doses, seizures or coma [1] [3].
4 · Clinical Features – “Anticholinergic Toxidrome”
| Mnemonic | Manifestations |
|---|---|
| Hot as a hare | Hyperthermia (↓ sweating) |
| Blind as a bat | Mydriasis, blurred vision, photophobia |
| Dry as a bone | Dry mouth, dry skin, absent bowel sounds |
| Red as a beet | Cutaneous flushing |
| Mad as a hatter | Agitated delirium, hallucinations, picking behaviour |
Additional findings: sinus tachycardia, hypertension (or later hypotension), ataxia, urinary retention, decreased lacrimation and cough reflex, possible ventricular dysrhythmias in severe cases [1] [5].
5 · Differential Diagnosis
- Sympathomimetic toxidrome (cocaine, amphetamines) – sweaty patient vs. dry skin.
- Serotonin syndrome – clonus > anticholinergic “dryness”.
- Neuroleptic malignant syndrome – drug history, rigidity.
- Delirium from infection, stroke or metabolic derangement.
6 · Diagnostic Approach
- Bedside evaluation: history of plant or drug exposure, characteristic vitals, pupillary exam and skin moisture [1] [6].
- Laboratory: electrolytes, creatine kinase (hyperthermia), creatinine; ECG for QRS/QT prolongation.
- Toxicology screens rarely detect tropanes rapidly; diagnosis remains clinical [1].
7 · Management & Treatment
7.1 Initial Stabilisation
- Airway / Breathing / Circulation (ABC) – intubate if airway reflexes fail or agitation compromises oxygenation.
- Cardiac monitoring for dysrhythmias; treat wide-complex tachycardia with sodium bicarbonate.
- Active cooling (evaporative, ice packs) if temperature > 38.5 °C.
7.2 Gastrointestinal Decontamination
Activated charcoal 1 g/kg orally/NG if presentation < 1 h post-ingestion and airway protected [6] [8]. Gastric lavage is seldom required.
7.3 Antidotal Therapy – Physostigmine
- Central acting reversible acetylcholinesterase inhibitor; counteracts both peripheral and CNS blockade.
- Adult dose: 1–2 mg IV slow push (0.5 mg/min); paediatric: 0.02 mg/kg (max 0.5 mg) – may repeat every 10–15 min if symptoms recur [5] [6].
- Contra-indications: suspected tricyclic antidepressant overdose (risk of asystole), AV block, severe asthma.
7.4 Symptomatic & Supportive Measures
- Benzodiazepines (diazepam or lorazepam) for agitation or seizures.
- IV fluids for rhabdomyolysis risk, Foley catheter for urinary retention.
- Anti-pyretics ineffective because fever is anticholinergic in origin—focus on external cooling.
- Consider lipid emulsion therapy if refractory cardiovascular collapse (rare case reports).
8 · Prognosis
With prompt recognition and physostigmine therapy, most patients recover within 24–48 h without sequelae. Delay or misdiagnosis may allow complications—heat stroke, aspiration pneumonia, ventricular tachycardia or multi-organ failure—to elevate morbidity and mortality, particularly in children and the elderly [[6]].
9 · Prevention & Public Health Notes
- Educate foragers and gardeners to identify Solanaceae plants accurately.
- Secure ophthalmic or parenteral atropine to prevent accidental paediatric access.
- Regulate over-the-counter herbal products containing belladonna alkaloids.
- School programmes warning adolescents about the dangers of so-called “natural” hallucinogens.
10 · Key Take-Home Points
- Atropine, hyoscyamine and scopolamine produce a distinct dry, flushed, delirious toxidrome.
- Diagnosis is clinical; sweat absence plus mydriasis and tachycardia are red flags.
- Physostigmine is the antidote of choice when serious CNS or cardiac manifestations emerge.
- Timely supportive care—airway control, cooling, benzodiazepines—prevents fatal complications.
- Accidental ingestion, especially in children, underscores the need for community education on toxic plants.
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