Master Anticholinergic Toxicity with a Mnemonic

Antimuscarinic agents block muscarinic receptors (type of ACh receptor), reversing muscarinic effects such as diarrhea, urination, miosis, bronchospasm, bradycardia, skeletal muscle excitation, lacrimation, sweating, and salivation. Therefore, signs and symptoms of antimuscarinic toxicity include flushing, dry skin and mucous membranes, mydriasis, altered mental status, and fever. These symptoms can be remembered with the mnemonic "red as a beet, dry as a bone, blind as a bat, mad as a hatter, and hot as a hare." The antidote for antimuscarinic toxicity is physostigmine salicylate. Physostigmine is the only reversible acetylcholinesterase inhibitor capable of directly antagonizing the CNS manifestations of anticholinergic toxicity because it is an uncharged tertiary amine that can efficiently cross the blood-brain barrier. By inhibiting acetylcholinesterase, there is an increased concentration of acetylcholine which augments stimulation at muscarinic receptors.