Table 4.

The characteristics and properties of alpha2 agonists

Medication	Metabolism	Elimination half-life	Onset of action after consumption (minutes)	Commentsa
Dexmedetomidine	CYP2A6 and glucoronidation	3 hours (prolonged in hepatic impairment)	5–15 (5–10 and 15 with and without loading dose administration)	Potentially significant hypotension and bradycardia or hypertension that do not resolve quickly upon abrupt discontinuation which occur more commonly in patients with cardiovascular instability or hypovolemia; rapid administration of loading dose may be associated with cardiovascular instability, tachycardia, bradycardia, or heart-block; does not induce the deep sedation needed for neuromuscular blockade
Clonidine	Hepatic metabolism to inactive metabolites	12–16 hours (41 hours in renal impairment)	10	Causes bradycardia, hypotension, and xerostomia; use with caution in patients with cardiovascular and cerebrovascular diseases; CNS depressant

Notes:

^aDrugs that alter the blood pressure level can affect hypertensive or hypotensive effect of alpha2 agonists. Tricyclic antidepressants can desensitize alpha2 adrenoreceptors and should be stopped 3 weeks prior to use of these two drugs.

Abbreviation: CNS, central nervous system.