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Key Points

  • Dexmedetomidine has sedative, hypnotic, analgesic, and sympatholytic properties without any respiratory depression.
  • It is commonly used as a component of general anesthesia, in the intensive care unit (ICU) for sedation in mechanically ventilated patients, for procedural sedation, as an emergence delirium prophylactic agent in pediatric patients, as a preoperative anxiolytic, and as an adjunct to local anesthetics in regional anesthesia and nerve blocks. Most recently, it has been used in the treatment of alcohol withdrawal.
  • Dexmedetomidine is a highly selective α2-adrenergic agonist that works at the locus ceruleus to produce a sedated yet arousable patient.
  • Adverse effects of dexmedetomidine include dose-dependent hypotension and bradycardia, as well as antimuscarinic effects.


Trade name- Precedex

Physiochemical Characteristics1

  • Dexmedetomidine ((S)-4-[1-(2,2-Dimethylphenylethyl]-3-H-imidazole) is available as a water-soluble salt that is typically diluted to 4 mcg/mL.

Mechanism of Action2

  • Dexmedetomidine is a highly selective α2-adrenergic agonist (α2:α1 = 1620:1), similar in nature to clonidine (α2:α1 = 220:1).
  • The agonism occurs in the central nervous system; specifically, the α2 receptors on neurons from the locus ceruleus are inhibited, which prevents norepinephrine release in the ventrolateral preoptic nucleus. This activates sleep centers in the brain.
  • The disinhibited nucleus reduces arousal in the midbrain, hypothalamic, and pontine nuclei, resulting in a sedated yet easily arousable patient.


  • The pharmacokinetics of dexmedetomidine are listed in Table 1.

Table 1. Pharmacokinetics of dexmedetomidine

  • Absorption
    • Only approved for intravenous (IV) use but well absorbed intranasally and via buccal mucosa.
    • Oral bioavailability is ~16% due to extensive first-pass effect.
  • Redistribution
    • Short initial distribution half-life (~6 minutes)
    • Readily crosses blood-brain and placental barriers
    • Exhibits linear pharmacokinetics in the range of 0.2-0.7 mcg/kg/hr (for up to 24 hours)
  • Metabolism
    • Undergoes almost complete biotransformation, involving both direct glucuronidation and the cytochrome P450 system with resultant inactive metabolites
    • Hepatic extraction ratio = 0.7
    • Clearance values are affected by varying levels of hepatic impairment.
  • Excretion
    • Dexmedetomidine and its metabolites are primarily (95%) eliminated through the renal route via urine.
    • Not significantly different in patients with severe renal impairment
  • Protein binding
    • Exhibits high-protein binding, with approximately 94% bound to plasma proteins

Systemic Effects2,3

The systemic effects of dexmedetomidine administration are listed in Table 2.

Table 2. Systemic effects of dexmedetomidine administration

Clinical Uses

Component of General Anesthesia1

  • Dexmedetomidine may be used as a component of a multimodal anesthetic. It has been demonstrated to decrease the need for other anesthetics, including sevoflurane and propofol.
  • It demonstrates both an intra- and postoperative opioid-sparing effect.

Sedation in ICU1

  • Although initially approved for only 24 hours of ICU sedation, multiple studies have demonstrated sufficient safety profile through 30 days.
  • Its use reduces the duration of mechanical ventilation and the ICU length of stay without a difference in mortality compared to traditional sedatives.4

Sedation for Medical Procedures

  • Dexmedetomidine is FDA-approved for therapeutic procedures, diagnostic procedures, and awake fiberoptic intubations.
  • Studies demonstrated a significantly reduced incidence of rescue midazolam required to complete the aforementioned procedures relative to placebo.5

Emergence Delirium Prophylaxis in Pediatric Anesthesia

  • An IV bolus dose of 0.5 mcg/kg immediately following induction demonstrated a significant reduction in the incidence of emergence delirium, minimal side effects, no delay in emergence, and a reduction in volatile and analgesic requirements.6

Preoperative Anxiolysis

  • Intranasal dexmedetomidine 1-2 mcg/kg is an effective anxiolytic premedication, particularly in the pediatric population; however, the clinical effect may not be observed for up to 30-45 minutes.7

Adjunct to Local Anesthetics in Regional Anesthesia

  • Perineural dexmedetomidine as an adjutant to local anesthetic nerve blocks increases the duration of the block.8
  • Administration of dexmedetomidine via the IV route has a similar efficacy to that of the perineural route.9

Adverse Effects

  • Antimuscarinic effects may occur due to α2 adrenal receptor-mediated inhibition of acetylcholine release.
  • Dexmedetomidine causes dose-dependent hypotension and bradycardia due to stimulation of presynaptic alpha receptors, leading to a decreased norepinephrine release and a decrease of central sympathetic flow.
  • Hypertension can occur with fast administration or with a loading dose due to stimulation of alpha subtype receptors on the vascular smooth muscles. It is usually self-limiting and does not require treatment.
  • No effective antagonist is available for human use.


  • In patients with baseline bradycardia, dexmedetomidine can worsen bradycardia.
  • In patients with hypotension, dexmedetomidine can worsen hypotension.
  • Consider avoiding a bolus in frail, critically ill, and elderly patients.
  • In patients with heart failure, there is evidence of possible exacerbation of myocardial dysfunction.10


  1. Weerink MAS, Struys MMRF, Hannivoort LN, et al Clinical pharmacokinetics and pharmacodynamics of dexmedetomidine. Clin Pharmacokinet. 2017;56(8):893-913. PubMed
  2. Abola R, Geralemou S, Szafran M, et al. Intravenous anesthetics. In: Barash PG, et al. (editors). Clinical Anesthesia. Philadelphia, Wolters Kluwer/Lippincott Williams & Wilkins, 2017: 496-8.
  3. Young ER. Clinical Anesthesia Procedures of the Massachusetts General Hospital, 6th Edition. Anesth Prog. 2005 Spring;52(1):45.
  4. Chen K, Lu Z, Xin YC, et al. Alpha-2 agonists for long-term sedation during mechanical ventilation in critically ill patients. Cochrane Database Syst Rev. 2015;1(1):CD010269. PubMed
  5. Bergese SD, Candiotti KA, Bokesch PM, et al; AWAKE Study Group. A phase IIIb, randomized, double-blind, placebo-controlled, multicenter study evaluating the safety and efficacy of dexmedetomidine for sedation during awake fiberoptic intubation. Am J Ther. 2010;17(6):586-95. PubMed
  6. Manning AN, Bezzo LK, Hobson JK, et al. Dexmedetomidine dosing to prevent pediatric emergence delirium. AANA J. 2020;88(5):359-64. PubMed
  7. Zhang X, Bai X, Zhang Q, et al. The safety and efficacy of intranasal dexmedetomidine during electrochemotherapy for facial vascular malformation: a double-blind, randomized clinical trial. J Oral Maxillofac Surg. 2013;71(11):1835-42. PubMed
  8. Wu HH, Wang HT, Jin JJ, et al. Does dexmedetomidine as a neuraxial adjuvant facilitate better anesthesia and analgesia? A systematic review and meta-analysis. PLoS One. 2014;9(3): e93114. PubMed
  9. Abdallah FW, Dwyer T, Chan VW, et al. IV and perineural dexmedetomidine similarly prolong the duration of analgesia after interscalene brachial plexus block: A randomized, three-arm, triple-masked, placebo-controlled trial. Anesthesiology. 2016 Mar;124(3):683-95. PubMed
  10. Page RL, O’Bryant CL, Cheng D, et al. Drugs that may cause or exacerbate heart failure: A scientific statement from the American Heart Association. Circulation. 2016;134(12): e261. PubMed