Tox: Anticholinergics, cholinergics

Question 1

Examples of anticholinergic agents

Answer 1

1) Pupillary dilators: e.g. atropine, homatropine, cyclopentolate.
2) Antispasmodics: e.g. buscopan, dicyclomine.
3) Motion sickness meds: e.g. scopolamine.
4) COPD meds (rarely cause systemic symptoms): tiotropium, ipratropium.
5) Airway secretion meds: glycopyrrolate.
6) Antiparkinsonian meds: benztropine, amantadine.
7) Urinary incontinence/bladder spasm meds: tolteridone, oxybutynin.
8) Meds w/ antichol SE: TCAs, antihistamines, cyclobenzaprine.
9) Plants: jimsonweed, nightshade.

Question 2

MOA of anticholinergic toxicity

Answer 2

Competitive antagonism of acetylcholine at muscarinic receptors in the CNS, PNS and sweat glands

Question 3

Anticholinergic toxidrome

Answer 3

Agitation, delirium, hallucinations, hyperthermia, dry/flushed, mydriasis, tachycardia, HTN, decreased bowel sounds, constipation, urinary retention.

‘Mad as a hatter, red as a beet, dry as a bone, blind as a bat, full as a flask, seizing like a squirrel, tachy as a pink flamingo’

Question 4

In addition to the anticholinergic toxidrome, what cardiac finding can be seen with diphenhydramine (benadryl) overdose?

Answer 4

Cardiac sodium channel blockade

Question 5

Treatment of anticholinergic toxidrome

Answer 5

Supportive: IVF, benzos (for sz, agitation, hyperthermia).
May require intubation, passive/active cooling for hyperthermia.
Antidote: physostigmine

Question 6

When is the antidote for anticholinergic toxidromes indicated? What are the potential complications?

Answer 6

Indications: agitation, delirium uncontrolled with benzos/’sedatives.’
Monitor for bradycardia and seizures (contraindicated if QRS>100ms or hx of TCA OD)

Question 7

What medications should specifically be avoided in anticholinergic toxidrome

Answer 7

BB, sedatives with anticholinergic effects (e.g. antipsychotics, benadryl)

Question 8

Complications of anticholinergic OD

Answer 8

1) Rhabdo (2* agitation, coma, hyperthermia)

2) QRS prolongation, wide complex dysrhythmias with certain agents (e.g. TCA, benadryl).

Question 9

Mxn of cholinergic toxidrome

Answer 9

Inhibition of acetylcholinesterase -> excess acetylcholine at muscarinic and nicotinic receptors.

Question 10

Symptoms of cholinergic toxidrome

Answer 10

SLUDGE plus the Killer B’s:

Salivation, lacrimation, urination, diarrhea, GI distress, emesis.
Bradycardia, bronchorrhea, bronchospasm.

May see: muscle fasciculations, miosis, hyperactive bowel sounds

Question 11

Examples of cholinergic drugs

Answer 11

1) Alzheimer meds (cholinesterase inhibitors): e.g. donepezil, galantamine, rivastigmine.
2) Myasthenia meds: e.g. pyridostigmine.
3) Insecticides: e.g. organophosphates, carbamates.
4) Chemical weapons: nerve agents (e.g. sarin)
5) glaucoma meds: e.g. pilocarpine
6) Nicotine
7) Mushrooms: e.g. Clytocybe and inocybe species

Question 12

potential ECG findings with cholinergic toxidrome

Answer 12

Bradycardia, AV block

Question 13

Treatment of cholinergic toxidrome

Answer 13

1) Atropine: dry airway secretions, treat unstable bradycardia (very high doses often required).
2) Benzos for seizures/agitation.
3) Pralidoxime (2-PAM): to regenerate acetylcholinesterase in organophosphate poisoning.