Clonidine and Eye

Q: Clonidine causes? - Select one

A) Miosis

B) Mydriasis

Answer: A

Clonidine is an alpha-2 adrenergic agonist. It was invented decades ago as a topical nasal decongestant. Later, many of its on- and off-label uses were utilized. Clonidine is now widely used for:

• Hypertension 
• Adjunctive for anesthetic sedation and analgesia
• Spinal anesthesia
• Opioid detoxification
• Alcohol withdrawal
• Smoking cessation
• Postmenopausal hot flashes
• Prevention of perioperative myocardial ischemia
• Attention deficit disorder with hyperactivity
• Refractory conduct disorder
• Tourette syndrome 
• Sleep disturbances

The classic clonidine "toxidrome” consists of four symptoms:

1. Depressed mental status
2. Miosis
3. Depressed respirations
4. Bradycardia and hypotension

#toxicity

#pharmacology

References:

1. Nishina K, Mikawa K, Uesugi T, et al. Efficacy of clonidine for prevention of perioperative myocardial ischemia: a critical appraisal and meta-analysis of the literature. Anesthesiology 2002; 96:323.

Glassman AH, Stetner F, Walsh BT, et al. Heavy smokers, smoking cessation, and clonidine. Results of a double-blind, randomized trial. JAMA 1988; 259:2863.

2. Clayden JR, Bell JW, Pellard P. Menopausal flushing: double-blind trial of a non-hormonal medication. Br Med J 1974; 9:490.

3. Manzon L, Nappe TM, DelMaestro C, Maguire NJ. Clonidine Toxicity. 2023 Jun 26. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. PMID: 29083752.