HWN Suggests

Toxicology 101: Talking Tox with The Dantastic Mr. Tox & Howard

Really we are talking about antimuscarinics and NOT antinicotinic agents, which cause paralysis. Parasympathetics control all glandular secretions. A pure antimuscarinic like atropine will give you the classic textbook symptoms: “Everything in your body that makes juice, is blocked” (Rusyniak 2018). Symptoms include dry mouth armpit. Some body systems like the heart and the eye are dually innervated by the sympathetic and parasympathetic systems. Blocking cholinergic receptors (the parasympathetic system) leaves the sympathetic system without a counterbalance and hence tachycardia and mydriasis (dilated pupils).

However, many drugs (like quetiapine) may have sympatholytic effects…

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Featured

 Anticholinergic Toxicity: Mad as a Hatter

ACh poisoning should be considered in all patients presenting with an altered mental status and physical exam findings consistent with ACh toxicity. The diagnosis of ACh toxicity is principally based on the physical exam and common clinical manifestations.

 Anticholinergic Toxicity: The Wacky, Tachy Patient

Anticholinergic toxicity can be challenging to manage. First, many patients are unable provide a history due to their symptoms or altered mental status, and family members are not always present to give additional information. Second, anticholinergic toxicity can mimic other disease states.

 Mad as a Hatter: Physostigmine for Delirium Control in Anticholinergic Toxicity

... delirium can be completely refractory to repeated doses of benzodiazepines and may actually be worsened by the use of some antipsychotics that have anticholinergic properties. Fortunately, there is a better approach: delirium reversal with physostigmine.

 So Bored, I Took My Mom’s Pills: Anticholinergic Toxicity

Treatment is primarily supportive. The goal is to prevent life-threatening complications including status epilepticus, rhabdomyolysis, hyperthermia, and cardiovascular collapse. Benzodiazepines are the most commonly used drug.

 Sympathomimetic vs. Anticholinergic Toxidromes

The clinical picture of sympathomimetic and anticholinergic can appear similar. Both may have agitation, confusion, delirium, seizures, tachycardia, hypertension, fever, and mydriasis. Distinguishing characteristics for anticholinergic syndrome are dry skin, absent bowel sounds, and urinary retention. Remember the colloquial description for anticholinergic toxicity; “Blind as a bat, mad as a hatter, red as a beet, hot as Hades (or hot as a hare), dry as a bone, the bowel and bladder lose their tone, and the heart runs alone.” Both sympathomimetic and anticholinergic syndrome respond well to benzodiazepines. Physostigmine can be used to treat delirium associated with anticholinergic syndrome after checking the EKG for signs of Na channel blockade.

Articles of Interest

Altered Mental Status- Is It Anticholinergic Toxicity?

Keep anticholinergic syndrome within your differential for a patient with altered mental status without a clear cause.

Anticholinergic or Sympathomimetic

Anticholinergic exposure paralyzes pupillary constrictor muscles and causes dilated pupils that do not react to light. Think about when you go to the eye doctor's office. They put homoatropine in your eyes so that when they look with the slit lamp they can see the retina without interference from pupillary constriction. Sympathomimetic exposure like cocaine activates pupillary dilator muscles, the constrictors are still intact and will give a reflexive constriction to light.

Anticholinergic Plants

Most plants with anticholinergic properties are from the family Solanaceae, and can be identified from their characteristic flowers. The Solanaceae family is extensively utilized by humans for food and medicine but is often rich in alkaloids that can cause life-threatening toxicity in humans.

Drugs Exhibiting Anticholinergic Toxicity

This week we delve into the anticholinergic toxidrome with a focus on management and the use of physostigmine.

Pearl of the Day: Anticholinergic Toxicity

sources: antihistamines, belladonna, mydriatic agents (e.g., tropicamide, cyclopentolate), TCAs, benztropine, phenothiazines, clozapine, olanzapine, Amanita muscaria - can be absorbed through ingestion, smoking, or ocular use - muscarinic blockade delays gastric emptying -> absorption and peak clinical effects are delayed - cholinergic receptors: muscarinic, nicotinic - central anticholinergic syndrome: fever, agitation, delirium, coma - peripheral anticholinergic syndrome: tachycardia, flushed dry skin, dry mouth, ileus, urinary retention - risk of toxicity is dose related.

Rapid Review: Anticholinergic Toxidrome

Classes of medications with anticholinergic properties include antihistamines, tricyclic antidepressants, and sleep aids.

The Ocular Anticholinergic Crisis

A two year-old normally healthy female arrives with her mother to the emergency department with the complaint of inconsolable crying. Shortly prior to this, she was examined in the ophthalmologist’s office and received a mydriatic during her ocular exam. About five minutes after the drops had been administered, the child began crying, initially rubbing her eyes, then progressing to whole body writhing and loud screaming.

Toxidromes; what’s your poison?

The anticholinergic toxidrome, as the name implies, is a group of drugs that interfere with the binding of acetylcholine to muscarinic receptors (Burns et al. 2000). The basic effect of blocking the muscarinic receptors, is to block the parasympathetic nervous system. Those of you who like the ‘brake and gas pedal’ analogy for the sympathetic versus parasympathetic nervous systems, can think of this as losing the brakes! T

Resources

Benadryl OD

A single therapeutic adult dose of diphenhydramine ranges from 25 to 100 mg every six hours. Manifestations of toxicity may occur after ingestion of three to five times the daily dose. The fatal oral dose is estimated to be between 20 to 40 mg/kg.

EMCrit Project

???? Dilated pupils. ???? Delirium. ???? Tachycardia. ???? Dry skin – This is an essential element, which helps separate anticholinergic toxidromes from sympathomimetic toxidromes.

Life in the Fastlane

Anticholinergic Toxidrome was one of the first flashcards I designed. I wanted to make a play on the old mnemonic: mad as a hatter, hot as hell, red as a beat, dry as a bone, and blind as a bat. I thought of the opening scene from Fear and Loathing in Las Vegas,...

StatPearls

Anticholinergic toxicity is commonly seen in the emergency department but is rarely fatal.

WikEM

Differential Diagnosis: Sympathomimetic toxicity, Red, dry skin and absent bowel sounds favors anticholinergic toxicity' Encephalitis. Head trauma. ETOH/sedative withdrawal. Neuroleptic Malignant Syndrome (NMS). Acute psychotic disorder.