Clonidine Overdose

Key Features

• Symptoms usually resolve in 24 hours

• Deaths are rare

• Similar symptoms may occur after application of topical nasal decongestants chemically similar to clonidine; for example

  • Oxymetazoline

  • Tetrahydrozoline

  • Naphazoline

  • Brimonidine

  • Apraclonidine

  • Tizanidine

Clinical Findings

• Bradycardia

• Hypotension

• Miosis

• Respiratory depression

• Coma

• Transient hypertension occasionally occurs as a result of peripheral α-adrenergic effects

Diagnosis

• Clinical

• Not detected in usual toxicology screenings

Treatment

• Symptomatic treatment is usually sufficient

  • Maintain blood pressure with intravenous fluids

  • Dopamine can also be used for hypotension

  • Atropine is usually effective for bradycardia

• Activated charcoal

  • Administer 60–100 g orally or via gastric tube, mixed in aqueous slurry

  • Do not use for comatose or convulsing patients unless it can be given by gastric tube and the airway is protected by a cuffed endotracheal tube

• There is no specific antidote

  • Tolazoline should not be used for clonidine overdose because its effects are unpredictable

  • Naloxone has had anecdotal success