Clonidine toxicity

2D molecular structure of Clonidine

Background

• Class: Imidazolines
  • Clonidine
  • Guanfacine
  • Oxymetazoline(Afrin)
  • Tetrahydrolozine (Visine)
  • Naphazoline (Naphcon)
  • Apraclonidine
• Alpha-2 and opioid receptor agonist

Clinical Features

• Cardiac
  • Bradycardia
  • Hypotension
• Neuro
  • Lethargy (may progress to apnea)
  • Miotic pupils
  • Respiratory depression

Differential Diagnosis

Toxidrome Chart

Finding	Cholinergic	Anticholinergic	Sympathomimetic	Sympatholytic^	Sedative/Hypnotic
Example	Organophosphates	TCAs	Cocaine	Clonidine	ETOH
Temp	Nl	Nl / ↑	Nl / ↑	Nl / ↓	Nl / ↓
RR	Variable	Nl / ↓	Variable	Nl / ↓	Nl / ↓
HR	Variable	↑	↑ (sig)	Nl / ↓	Nl / ↓
BP	↑	↑	↑	Nl / ↓	Nl / ↓
LOC	Nl / Lethargic	Nl, agitated, psychotic, comatose	Nl, agitated, psychotic	Nl, Lethargic, or Comatose	Nl, Lethargic, or Comatose
Pupils	Varriable	Mydriatic	Mydriatic	Nl / Miotic
Motor	Fasciculations, Flacid Paralysis	Nl	Nl / Agitated	Nl
Skin	Sweating (sig)	Hot, dry	Sweating	Dry
Lungs	Bronchospasm / rhinorrhea	Nl	Nl	Nl
Bowel Sounds	Hyperactive (SLUDGE)	↓ / Absent	Nl / ↓	Nl / ↓

^Consider Sympatholytic when looking at Sedative OD or someone who doesn't respond to Narcan

Withdrawal from substances have the opposite effect

Management

• Respiratory/neuro depression
  • Naloxone
    • High dose may be required (up to 10mg)
    • Not always effective
• Bradycardia
  • Atropine
• Hypotension
  • IVF

See Also

Toxicology (Main)

Authors

Ross Donaldson