Etomidate is an ultrashort-acting, non-barbiturate hypnotic agent used primarily for the induction of general anesthesia and sedation for brief medical procedures.
Etomidate (brand name Amidate, among others) is a short-acting intravenous (IV) anesthetic agent belonging to the carboxylated imidazole class.
Etomidate is a prescription medication administered only by trained anesthesia or emergency providers. It is not for self-use or outpatient oral/sedative purposes.
Decisions about its use (vs. alternatives like ketamine or propofol) depend on patient factors such as hemodynamic status, adrenal function, and procedure type.
It is favored in emergency medicine—particularly for rapid sequence intubation (RSI)—because it maintains hemodynamic stability, meaning it has minimal impact on a patient’s blood pressure and heart rate.
It is administered exclusively through intravenous (IV) injection.
It works rapidly, typically inducing unconsciousness within one minute, with effects lasting approximately 3 to 5 minutes due to quick redistribution and metabolism.
Mechanism: It acts as a positive allosteric modulator of GABA receptors in the central nervous system, enhancing inhibitory signals to reduce neuronal excitability.
Critically, etomidate provides no analgesic, it only causes sedation and amnesia.
Adrenal Suppression: A single dose can inhibit the enzyme 11β-hydroxylase, suppressing cortisol production for up to 24–72 hours.
Common reactions include myoclonus (involuntary muscle twitching), pain at the injection site, and post-operative nausea or vomiting.
Etomidate has been identified as an additive in illicit vape liquids leading to severe health risks like seizures, psychosis, and dependence.
Etomidate is primarily used for the induction of general anesthesia and for procedural sedation or rapid sequence intubation (RSI), especially in hemodynamically unstable patients.
Usage:
Induction of anesthesia: Rapid onset, usually within 30–60 seconds, with a short duration of action 3–8 minutes for a standard dose, due to redistribution.
Rapid sequence intubation (RSI): Preferred in emergency settings, trauma, shock, or cardiovascular disease because it causes minimal blood pressure drop or respiratory depression compared to alternatives like propofol.
Short procedures: Such as joint reductions, cardioversion, or electroconvulsive therapy.
Off-label: Occasionally for brief sedation or (rarely) to inhibit steroidogenesis in severe Cushing syndrome.
It has no analgesic properties, so it is often combined with opioids or other agents.
Etomidate acts primarily as a positive allosteric modulator of GABA-A receptors (especially those with β2 and β3 subunits).
It enhances GABA binding, increasing chloride influx, hyperpolarizing neurons, and inhibiting the reticular activating system to produce hypnosis/sedation.
The clinically used form is the R(+)-enantiomer, which is far more potent than the S(-) form.
Dosing-Typical Adult Induction 0.2–0.6 mg/kg IV (usual ~0.3 mg/kg), injected over 30–60 seconds. Onset: <1 minute. Duration: Correlates with dose; each additional 0.1 mg/kg adds roughly 100 seconds of unconsciousness.
Lower doses may be used in elderly patients or those with hepatic impairment.
Advantages
Excellent hemodynamic stability: Minimal effects on blood pressure, heart rate, or cardiac output (slight decrease in systemic vascular resistance, but overall very stable). Ideal for hypovolemic, septic, or cardiac patients.
Rapid recovery.
No significant histamine release.
Side Effects and Notable Risks
Pain on injection (common, due to the propylene glycol vehicle; lipid emulsions may reduce this in some formulations).
Myoclonus (involuntary muscle movements) — often mitigated with a small dose of benzodiazepine or opioid pretreatment. Nausea/vomiting. Adrenal suppression: The most significant concern.
Etomidate reversibly inhibits 11β-hydroxylase (and to a lesser extent 17α-hydroxylase) in the adrenal cortex, blocking cortisol (and aldosterone) synthesis.
A single induction dose suppresses adrenals for ~4–8 hours (sometimes up to 24 hours).
This is usually clinically insignificant in healthy patients but can be problematic in critically ill, septic, or trauma patients, or those with preexisting adrenal issues.
Continuous infusions were largely abandoned due to increased mortality from adrenal insufficiency in ICU settings.
Other: Hiccups, transient apnea possible but less than with other agents.
In patients with known adrenal insufficiency or high-risk sepsis, stress-dose steroids may be considered if etomidate is used.
Pharmacokinetics Highly lipid-soluble; rapid redistribution from brain to muscle/fat.
Metabolized in the liver (mainly hydrolysis to inactive carboxylic acid metabolite).
Excreted mostly in urine (~75% in first 24 hours).
Elimination half-life: ~2–5 hours (context-sensitive half-time is short due to redistribution).