Pharmacology · Intravenous anaesthetics
Dexmedetomidine !
Alpha-2 agonist sedative that leaves the patient calm but rousable, without much respiratory depression. It causes bradycardia and hypotension.
Updated 2026-11-01
Also called: Dexmedetomidine hydrochloride
The figure shows dexmedetomidine bound to the human alpha-2A adrenergic receptor in its active complex with a Go protein.
Mechanism of action
Dexmedetomidine is a relatively selective agonist of alpha-2 adrenergic receptors. In the locus coeruleus it reduces the firing of noradrenergic neurons and produces a sedation that resembles natural sleep: the patient responds and cooperates when stimulated. By lowering sympathetic tone it reduces heart rate and blood pressure; at the start, blood pressure may rise through stimulation of vascular alpha-2 receptors.
- Stimulates alpha-2 receptors in the locus coeruleus
- Noradrenergic firing falls: sleep-like sedation
- Patient rousable, with little respiratory depression
- Lower sympathetic tone: bradycardia and hypotension
Pharmacokinetics
- Metabolism
- Almost complete hepatic metabolism: direct glucuronidation and hydroxylation by CYP2A6; liver impairment reduces its clearance.
- Elimination
- Kidney, as inactive metabolites.
- Onset and duration
- Intravenous infusion; it can be started with a loading infusion.
Indications
- Sedation of intubated, ventilated ICU patients
- Sedation of non-intubated patients before and during procedures
- Sedation for awake fibreoptic intubation
Adverse effects
Common
- Hypotension
- Bradycardia
- Dry mouth
- Nausea
- Transient hypertension during the loading infusion
Contraindications
- Hypersensitivity to dexmedetomidine
Key interactions
- Anaesthetics, sedatives, hypnotics and opioids
- Add sedation; lower doses may be needed.
- Other vasodilators or drugs that slow the heart (beta-blockers)
- Additive hypotension and bradycardia.
What is monitored
- Continuous heart rate, rhythm and blood pressure
- Sedation level on a scale
- Urine output, sodium and urine osmolality (diabetes insipidus)
- Withdrawal signs on stopping
Administration and safety
- Continuous intravenous infusion by pump; rapid infusion or bolus raises the risk of bradycardia and sinus arrest.
- The approved ICU sedation indication does not exceed 24 hours of infusion.
- Ready-to-use presentations and concentrates that must be diluted both exist: confirm which one is at hand.
Nursing care
- Before: baseline heart rate and blood pressure; caution in hypovolaemia, heart block or severe ventricular dysfunction.
- During: watch for bradycardia and hypotension; keep atropine available.
- Remember that the patient may wake with stimulation: this does not mean the drug is failing.
- When a long infusion stops: watch for agitation, tachycardia and hypertension.
Pregnancy and breastfeeding
Human data are too limited to establish a risk in pregnancy.
Test yourself
Think of the answer, then tap the question to see it.
Why can a patient sedated with dexmedetomidine wake when spoken to?
Because it produces a sleep-like sedation through its action in the locus coeruleus, not a global depression of the nervous system; waking with stimulation does not mean lack of effect.
What are the most common adverse effects of dexmedetomidine?
Hypotension, bradycardia and dry mouth.
Which antihypertensive drug shares dexmedetomidine's mechanism?
Clonidine, another alpha-2 adrenergic agonist.
Related drugs
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - DEXMEDETOMIDINE HYDROCHLORIDE injection (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 24 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.