Etomidate: Formula, Presentation, Indications, Action Mechanism, Side Effects and Interactions

It is a unique drug used to induce general anesthesia and sedation.

Among the induction drugs of general anesthesia, Etomidate is the only imidazole with the most favorable therapeutic index for administering a single bolus.

Etomidate in typical anesthetic induction doses does not produce heart rate, blood pressure, or cardiac output changes.

This medication does not block sympathetic responses to laryngoscopy and intubation, produces less apnea than barbiturates or propofol, there is no release of histamine, and allergic reactions are rare.

Due to its mild hemodynamic effects, Etomidate is valid for the induction of general anesthesia in patients undergoing cardiac surgery with poor cardiac function, valvular or ischemic heart disease.

Also, for hemodynamically unstable or hypovolemic patients.

Due to its effect on the decrease in intraocular pressure, it is appropriate for ophthalmological surgeries.


It also decreases intracranial pressure, oxygen consumption, and blood flow in the brain, making it a good option for neurosurgery.

Chemical formula

  • C14H16N2O2.


  • 10 ml ampoules containing 20 mg (2 mg / ml).


It has been proposed as an induction anesthetic and maintenance of general anesthesia; it is an alternative medicine for the induction of anesthesia, especially in unstable cardiovascular systems.

Mechanism of action

Etomidate is a hypnotic non-barbiturate that acts at the level of the reticular activation system, responsible for regulating the waking state for provoking anesthesia.

Etomidate is an imidazole compound that seems to depress the function of the central nervous system through the neurotransmitter: gamma-aminobutyric acid.

The duration of action of Etomidate is intermediate between the time of thiopental and methohexital, and the recovery of a single dose is rapid with few residual effects.

Like the barbiturates and propofol, the Etomidate does not induce analgesia but induces unconsciousness within the circulation time of the medication.

Its recovery is rapid as a result of extensive redistribution and fast metabolism.


Intravenous anesthesia with an initial dose of 0.2 to 0.6 mg per kg of body weight, for 30 to 60 seconds for the induction of anesthesia, and the maintenance of 5 to 20 mg/kg of body weight per minute.

Sedation procedure in intravenous administration, the initial dose is 0.1 to 0.2 mg/kg of body weight, followed by 0.05 mg/kg of body weight every 3 to 5 minutes as necessary.

In children older than ten years and geriatric patients, it is the same as adults.

This solution is highly irritating, so you should avoid administration through small vessels; in some cases, you can consider the previous administration of lidocaine.

Oral transmucosal Etomidate has been used to induce sedation; rectal administration has been used to induce general anesthesia in pediatric patients.

Side effects

Several unfavorable side effects associated with the administration of the Etomidate have been reported.

In the first studies, the pain was observed in the area where the injection was placed, and myoclonic movements were presented during the induction of general anesthesia.

It was found that the pain in the injection was worse with the Etomidate in aqueous solutions in comparison with the propylene glycol formulation.

The lipid formulation seems to further reduce the incidence of pain due to injection and hemolysis.

It has been shown that myoclonus increases with the dose of Etomidate and can be attenuated by induction in divided doses or premedication with benzodiazepines, thiopental, dexmedetomidine, and opioids.

Significant adverse reactions can be divided into two groups according to the percentage of occurrence:

Occurrence greater than 10%:

  • Gastrointestinal reactions: Nausea, vomiting when leaving anesthesia.
  • Local reactions: Pain at the injection site.
  • Neuromuscular and skeletal responses: Presence of myoclonus, transient skeletal movements, uncontrolled eye movements. Reactions have also been observed as hiccups with an occurrence of 1 to 10%

Occurrence less than 1% (limited to significant or life-threatening):

Apneas, arrhythmias, bradycardias, decreases in cortisol synthesis, hypertension, hypotension, hypoventilation and hyperventilationlaryngospasm, and tachycardia, have been reported.

Warnings and contraindications

Etomidate is contraindicated in cases of hypersensitivity to the active component or any other element of the formulation.

It should be used with caution in patients with:

  • A patient with a history of seizures or focal epilepsy.
  • In the cases of immunosuppressed patients and cases of transplantation due to adrenal involvement.
  • In septic patients.
  • Etomidate is contraindicated in pregnancy and childbirth.

There are concerns related to the adverse effects of the production of adrenal steroids since Etomidate inhibits 11-B-hydroxylase.

This is an essential enzyme in the production of adrenal steroids.

A single induction dose blocks the average increase in adrenal cortisol production induced by stress for 4 to 8 hours and up to 24 hours in elderly and debilitated patients.

In cases of continuous infusion of Etomidate for sedation in intensive care units, mortality may increase because patients may not be able to respond to stress.

The replacement of exogenous corticosteroids should be considered in those patients subjected to severe stress.

The use of Etomidate in special populations should be restricted; in the case of pediatric patients, safety and efficacy have not been established in children under ten years of age.

In cases of safety problems with drugs, due to confusion of Etomidate with etidronate, this is a high-alert medicine since they have a greater risk of causing significant damage to the patient when used by mistake.


Within interactions, although not considered significant, we found the inhibition of pseudo-cholinesterase activity is likely to increase the effects of succinylcholine.

When used concomitantly with narcotics and volatile anesthetics, it may potentiate the effects of non-depolarizing relaxants.