Anticholinergic Syndrome
Definition
Dry as a bone, red as a beet, blind as a bat, mad as a hatter, hot as a hare. Hallmark of Datura, belladonna and scopolamine.
- Classic mnemonic
- Dry as a bone, red as a beet, blind as a bat, mad as a hatter, hot as a hare
- Mechanism
- Blockade of muscarinic acetylcholine receptors
- Implicated plants
- Datura, belladonna, and other tropane-alkaloid plants
- Implicated alkaloid
- Scopolamine, along with atropine and hyoscyamine
Common questions
Why does anticholinergic poisoning cause dry skin and flushing rather than sweating?+
Muscarinic receptor blockade shuts down sweat gland activation and causes cutaneous vasodilation, so the skin becomes hot, dry, and flushed instead of the clammy, sweaty presentation seen in many other poisonings.
How is anticholinergic syndrome distinguished from other toxidromes at autopsy or in a live patient?+
The combination of dilated pupils, dry mucous membranes, urinary retention, absent bowel sounds, and delirium together points to anticholinergic toxicity, whereas a sympathomimetic or cholinergic toxidrome instead presents with sweating and either agitation with normal pupils or pinpoint pupils and secretions.
Related terms
- Cardiac Glycoside
- A steroidal compound that inhibits the sodium-potassium ATPase pump in cardiac myocytes, raising intracellular calcium and producing bradyarrhythmia, AV block and hyperkalaemia....
- Cyanogenic Glycoside
- Sugar-cyanide conjugate (amygdalin in bitter almonds, linamarin in cassava). Hydrolysis releases HCN, which inhibits cytochrome c oxidase.
- Diterpene Alkaloid
- Aconitine and mesaconitine in Aconitum. Bind site 2 of the voltage-gated sodium channel and prevent inactivation. Refractory ventricular arrhythmia, death within hours.
- Keller-Kiliani Test
- Cardiac-glycoside test. Glacial acetic acid + FeCl3 layered with H2SO4 gives a reddish-brown ring and blue-green upper layer for 2-deoxysugars.
- Toxalbumin / Lectin
- Two-chain plant protein (A-chain catalytic, B-chain lectin) that depurinates a specific adenine in 28S rRNA, inactivating the 60S ribosomal subunit. Abrin and...
- Tropane Alkaloid
- A class of bicyclic nitrogen-containing alkaloids (atropine, hyoscyamine, scopolamine) produced by Solanaceae such as Datura and Atropa belladonna. Acts as a competitive...
- Vitali-Morin Test
- Tropane-alkaloid colour test. Fuming HNO3, evaporate, then alcoholic KOH gives violet with atropine and hyoscyamine. Negative on cocaine.