Toxidromes

There are five classic syndromes of toxic ingestion ("toxidromes") that should be recognized.

Class	Examples	Vital Signs	Mental Status	Pupils	Other Findings
Sympathomimetics	cocaine, amphetamines, serotonergic drugs	+HR, +RR, +BP, +temp	++	mydriasis	tremor, warm skin, diaphoresis
Sedative/Hyponotics	benzodiazepines	-HR, -RR, -BP, -temp	--	normal	nystagmus, hyporeflexia
Opioids	heroin, methadone	respiratory failure	--	miosis	hyporeflexia
Anticholinergics	TCAs, antihistamines, atropine	+HR, +BP, +temp	++	mydriasis	skin red dry hot, urinary retention
Cholinergics	organophosphates, muscarinics, mushrooms	-HR, -temp, +RR	--	miosis	salivation, lacrimation, urination, defectation, emesis

Sedative/Hypnotics

Flumazenil is the preferred antidote to benzodiazepine overdose. It is a competitive inhibitor of the GABA(A) receptor.

Opioids

Naloxone is the preferred antidote to opioid overdose. It is a nonselective competitive opioid receptor antagonist with a high affinity for the μ-opioid receptor. Half-life is short, so it may be necessary to administer multiple times or set up an infusion if the opioid has a long half-life.

Anticholinergics

Physostigmine is the preferred antidote to anticholinergic overdoses.

Cholinergics

Pralidoxime +/- atropine are the preferred antidotes to cholinergic overdoses, specifically organophosphates.