Sedative · Alpha-2 agonist

Dexmedetomidine (Precedex)

Also called Precedex

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Indications

Sedation of intubated, ventilated adults (label: up to 24 h; trials ran for days)
Procedural sedation of non-intubated adults and children, including awake fiberoptic intubation
Light ICU sedation: PADIS 2025 favors it over propofol when light sedation or less delirium is the goal
Agitated delirium that blocks extubation (off-label; PADIS 2018)
Adjunct for autonomic signs of alcohol withdrawal (off-label)

Dosing

Dexmedetomidine drip card and mL/h converterStart: 0.2–0.7 mcg/kg/h; the loading dose is often skipped

Mechanism of action

Dexmedetomidine is a highly selective α₂-adrenergic agonist (α₂:α₁ ratio 1620:1, against 220:1 for clonidine). At α₂A receptors in the locus coeruleus it activates inhibitory Gi proteins: cAMP falls, potassium channels open and hyperpolarize the neuron, and calcium entry drops, so norepinephrine release falls. Quieting the locus coeruleus engages the brain's natural sleep pathways, giving rousable sedation, and spinal α₂ receptors reduce pain transmission. It has no GABA-A activity.

Pharmacology

CNS: rousable, cooperative sedation like non-REM sleep; little amnesia; modest opioid-sparing analgesia; not anticonvulsant and not enough alone for deep sedation
Cardiovascular: biphasic. A load or fast bolus stimulates vascular α₂B receptors, causing brief hypertension with reflex bradycardia; central sympatholysis then lowers BP and heart rate, occasionally to sinus arrest
Respiratory: little depression; the CO₂ response is preserved, so it can run through extubation
Other: diuresis (diabetes insipidus is a label warning), less shivering, dry mouth, and fever that resists cooling (label)

Pharmacokinetics

Onset	About 5–15 min IV with a loading infusion; slower without one
Context-sensitive half-time	4 min after a 10-min infusion; 250 min after an 8-h infusion (Venn 2002)
Half-life	Distribution 6 min; terminal about 2 h (label), 2–4 h in ICU patients
Distribution	Vd at steady state about 118 L (1.3–2.5 L/kg), larger with low albumin
Protein binding	94%
Metabolism	Liver: direct N-glucuronidation and CYP2A6 hydroxylation; metabolites inactive
Clearance	About 39 L/h (label); high hepatic extraction, so it falls with low cardiac output and liver disease
Elimination	Urine (95%) as metabolites; under 1% unchanged
Organ failure	Severe liver impairment halves clearance (half-life about 7 h), so reduce the dose; kidney failure leaves kinetics unchanged (label)
Routes	IV; sublingual film (Igalmi) for agitation in schizophrenia or bipolar disorder

Chemistry

(S)-4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole: an imidazole, the active S-enantiomer of the racemic veterinary drug medetomidine
A close relative of clonidine (an imidazoline), but about 8 times more α₂-selective and much shorter-acting
pKa 7.1: about two-thirds un-ionized at pH 7.4 and lipophilic, hence the 6-min distribution half-life
Water-soluble hydrochloride, preservative-free: a 4 mcg/mL premix in 0.9% sodium chloride, or a 100 mcg/mL concentrate to dilute to 4 mcg/mL
Do not run it in the same catheter as blood or plasma; it can adsorb to natural rubber (label)

Adverse effects and cautions

In the one-pagers

Practice Airway and RSI questions free196 exam-style questions with rationales on the topic where Dexmedetomidine comes up most. No account or download needed.

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Propofol

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Sources

FDA label: Precedex (2026)
Weerink 2017 (review)
Venn 2002
PubChem: dexmedetomidine

For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow your local protocols and medical direction.