0071643192.pdf

TOXICOLOGY

A 23-year-old male with a history of depression presents to the ED via

EMS for altered mentation. On presentation he is agitated and delirious.

Physical examination reveals tachycardia, dilated pupils, mild hyperten-

sion, fever, dry mucous membranes, and flushed, dry skin. Ingestion of which

groups of drugs is suggested by this patient’s presenting symptoms?

This patient is presenting with an anticholinergic toxidrome, which may be

caused by over-the-counter antihistamines, certain plants, or a variety of pre-

scription medications.

ANTICHOLINERGICS/CHOLINERGICS

Anticholinergics

The anticholinergic toxidrome may result from exposure to medications or
plants (see Table 6.7).

MECHANISM/TOXICITY

■ Competitive antagonism of acetylcholine at muscarinic and central ner-
vous system cholinergic receptors

SYMPTOMS/EXAM

■ Agitation, delirium, hallucinations ↔coma, seizures.
■ Hyperthermia
■ Dry, flushed, warm skin
■ Mydriasis and blurry vision
■ Tachycardia
■ Sinus tachycardia
■ Tachydysrhythmias are unusual, but may occur.
■ QRS prolongation and wide complex dysrhythmias may be seen with cer-
tain agents (TCAs, diphenhydramine), but is due to other drug effects
(Na++channel blockade).

TABLE 6.7. Common Anticholinergic Agents

Prescription Medications

Antipsychotics

Scopolamine

Gastrointestinal antispasmodics

Skeletal muscle relaxants

Over-the-Counter Medications

Antihistamines

Plants

Jimsonweed (Datura stramonium)

Deadly nightshade (Atropa belladonna)