Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ETOMIDATE vs ETHRANE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Etomidate is a nonbarbiturate hypnotic agent that acts as a positive allosteric modulator of the gamma-aminobutyric acid (GABA) type A receptor, enhancing GABA-mediated inhibition in the central nervous system. It produces rapid anesthesia with minimal cardiovascular and respiratory depression.
Enflurane is a volatile inhalational anesthetic that potentiates GABA-A receptor activity and inhibits excitatory neurotransmission, resulting in general anesthesia.
Induction of general anesthesia,Procedural sedation (off-label),Rapid sequence intubation (off-label)
Induction and maintenance of general anesthesia
Induction: 0.2–0.6 mg/kg IV over 30–60 seconds. Maintenance: 10–20 mcg/kg/min IV continuous infusion.
1-5% inspired concentration via inhalation, titrated to effect for maintenance of general anesthesia.
Terminal elimination half-life: 2.9–5.3 hours (context: redistribution shortens clinical effect; hepatic impairment prolongs).
Context-sensitive half-life: approximately 2-5 minutes after short procedures; prolonged after prolonged administration due to slow washout from fat stores.
Etomidate is extensively metabolized in the liver via hydrolysis of the ester side chain by hepatic esterases to its principal metabolite, etomidate carboxylic acid. A minor metabolite is formed via N-demethylation. Metabolites are inactive.
Primarily hepatic via cytochrome P450 (CYP2E1); minor metabolism to fluoride ions.
Renal: 75% as metabolite (carboxylic acid), 2% unchanged; fecal/biliary: minimal.
Primarily exhaled unchanged via lungs (>95%); less than 5% metabolized in liver to fluoride ion and other metabolites, with renal excretion of metabolites.
76% bound to albumin.
Approximately 30-40%, primarily to albumin.
Vd: 2.5–4.5 L/kg (large, indicating extensive tissue uptake).
Vd: 1.2-2.0 L/kg, indicating extensive distribution into tissues, especially fat.
IV: 100% (only route used clinically).
By inhalation: 100% as delivered; not administered orally.
No dose adjustment required for renal impairment. Hemodialysis does not alter dosing. Use caution in severe renal failure due to propylene glycol vehicle if prolonged infusion.
No dose adjustment required for GFR >10 m L/min; use with caution in severe renal impairment (GFR <10 m L/min) due to potential accumulation of inorganic fluoride metabolites.
No specific adjustment for Child-Pugh class. However, prolonged effect may occur in severe hepatic impairment; reduce induction dose by 50% and titrate to effect.
No specific Child-Pugh based adjustment; use with caution in severe hepatic impairment as metabolism may be decreased.
Induction: 0.2–0.6 mg/kg IV (max 40 mg). Age >10 years: use adult dosing. Neonates and infants: reduce dose to 0.3 mg/kg due to higher volume of distribution.
Induction: 2-5% inspired concentration; Maintenance: 1-3% inspired concentration, adjusted to age and response.
Induction: 0.15–0.3 mg/kg IV (50% reduction of adult dose) due to decreased clearance and increased sensitivity. Use lower end of dosing range.
Lower inspired concentrations (0.5-2%) recommended due to increased sensitivity and reduced clearance; titrate to effect.
Etomidate has been associated with mortality in children. It should not be used in children younger than 6 months of age. (This warning is included in the prescribing information based on FDA labeling; specific text may vary.)
None
Inhibition of adrenal steroidogenesis (adrenal suppression) due to blockade of 11-beta-hydroxylase, leading to decreased cortisol and aldosterone production; may persist for 12-24 hours after single dose,Myoclonic movements during induction (involuntary muscle contractions),Hypotension and bradycardia (less common than with other induction agents),Venous irritation and pain on injection (may be reduced by using larger veins)
May cause dose-dependent cardiovascular depression,Risk of malignant hyperthermia,Potential for nephrotoxicity due to fluoride release,Hepatotoxicity risk, especially with repeated use,Neurologic effects including seizure activity at high doses
Hypersensitivity to etomidate,Patients with acute porphyria (may be porphyrinogenic)
Known hypersensitivity to enflurane or other halogenated anesthetics,Known or suspected susceptibility to malignant hyperthermia,Severe hepatic impairment,Uncontrolled epilepsy
No specific food interactions are known. Etomidate is administered intravenously and does not have oral bioavailability. However, concurrent use of drugs that affect CYP3A4 (e.g., grapefruit juice) is not clinically significant due to IV route.
No specific food interactions. Patient must follow preoperative fasting guidelines (nil per os, NPO) as directed by anesthesiologist to reduce risk of aspiration.
Etomidate is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses higher than human doses. There are no adequate and well-controlled studies in pregnant women. First trimester exposure may be associated with a slightly increased risk of congenital malformations, but data are limited. Risks to the fetus should be weighed against the benefits of maternal anesthesia. The drug is not recommended during pregnancy unless clearly needed, especially during organogenesis. In the second and third trimesters, etomidate may cause fetal central nervous system depression and respiratory depression if used near term.
FDA Category B. No evidence of teratogenicity in animal studies; human data limited. Use only if clearly needed during pregnancy, especially first trimester due to potential fetal hypoxia from maternal hypotension.
It is unknown whether etomidate is excreted in human breast milk. The molecular weight (244.3) suggests potential excretion into milk. The milk-to-plasma ratio (M/P) has not been determined. Due to the short half-life (2–5 hours) and use as a single induction dose, transfer to the infant is likely minimal. However, caution is advised. The American Academy of Pediatrics classifies etomidate as 'compatible' with breastfeeding after a single dose, but data are insufficient for repeated or prolonged use. Infants should be monitored for sedation and respiratory depression.
Excreted in breast milk in low amounts; M/P ratio not established. Consider benefits of breastfeeding vs. risk of infant exposure. Minimal systemic absorption in infant expected.
No specific dose adjustments are recommended for etomidate during pregnancy, but the dose should be individualized to achieve the desired level of anesthesia with the lowest effective dose. Physiologic changes in pregnancy (e.g., increased plasma volume, altered protein binding) may affect pharmacokinetics, but etomidate is rapidly redistributed and has a short duration of action. The standard induction dose of 0.2–0.6 mg/kg IV is used. Close monitoring of maternal and fetal status is advised. In cesarean section, lower doses may be considered to reduce fetal depression.
No specific dose adjustments required for pregnancy; however, MAC decreases by approximately 30% during pregnancy due to hormonal changes and increased progesterone. Monitor depth of anesthesia closely.
Etomidate is an induction agent of choice in hemodynamically unstable patients due to minimal cardiovascular depression. Adrenal suppression occurs even after a single dose, manifesting as decreased cortisol and aldosterone synthesis via 11β-hydroxylase inhibition. Administer slowly over 30-60 seconds to reduce myoclonus and pain on injection. Use a lower dose (0.2-0.3 mg/kg IV) in elderly or debilitated patients. Etomidate is not recommended for rapid sequence intubation in septic shock due to risk of adrenal insufficiency; consider ketamine as alternative. Prolonged infusion is not advised due to propylene glycol vehicle and adrenal suppression.
ETHRANE (enflurane) is a potent inhalation anesthetic. Its use is limited due to risk of seizures at high doses and potential for nephrotoxicity from fluoride ion release. Avoid in patients with history of seizures or renal impairment. Rapid induction and recovery; use with caution in hypotensive patients due to myocardial depression. Malignant hyperthermia trigger.
You may experience brief involuntary muscle movements during injection, which are usually harmless.,Tell your doctor if you have adrenal gland problems or are taking corticosteroids.,This drug may cause a temporary decrease in your body's ability to produce stress hormones.,Avoid driving or operating machinery until the effects of the medication have completely worn off.,Report any severe pain at the injection site or unusual weakness after the procedure.
You will receive this anesthesia medication only in a hospital setting under expert supervision.,Possible side effects include nausea, vomiting, shivering, and confusion after waking up.,Tell your doctor if you have a history of seizures, kidney problems, or muscle disorders.,Avoid driving or operating machinery for at least 24 hours after anesthesia.,Do not eat or drink for the time specified by your healthcare team before surgery.
"Concurrent administration of etomidate and fluoxetine may potentiate the anesthetic and sedative effects, as fluoxetine inhibits CYP3A4 which is involved in the metabolism of etomidate, leading to increased etomidate plasma concentrations and prolonged recovery time. Additionally, both drugs can cause QTc interval prolongation, increasing the risk of torsades de pointes and other ventricular arrhythmias. Patients may experience enhanced central nervous system depression, respiratory depression, and hypotension."
"The combination of Promazine, a phenothiazine antipsychotic with strong alpha-adrenergic blocking activity, and Etomidate, a non-barbiturate hypnotic used for induction of anesthesia, can lead to an increased risk of hypotension due to additive vasodilatory effects. Promazine's alpha-1 receptor antagonism impairs compensatory vasoconstriction, while Etomidate suppresses adrenal cortisol synthesis, potentially blunting the stress response and further reducing hemodynamic stability. Clinically, this interaction may result in profound hypotension, especially in hypovolemic or elderly patients, requiring careful dose titration and monitoring."
"The coadministration of oxazepam, a benzodiazepine that enhances GABA-A receptor activity, with etomidate, a non-barbiturate anesthetic that also potentiates GABA-A receptor function, results in additive central nervous system (CNS) depression. This synergistic interaction can lead to excessive sedation, respiratory depression, hypotension, and prolonged recovery from anesthesia. Patients are at increased risk of apnea, hypoxia, and hemodynamic instability, particularly during induction and maintenance of anesthesia."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ETOMIDATE vs ETHRANE, answered by our medical review team.
ETOMIDATE is a General Anesthetic that works by Etomidate is a nonbarbiturate hypnotic agent that acts as a positive allosteric modulator of the gamma-aminobutyric acid (GABA) type A receptor, enhancing GABA-mediated inhibition in the central nervous system. It produces rapid anesthesia with minimal cardiovascular and respiratory depression.. ETHRANE is a General Anesthetic that works by Enflurane is a volatile inhalational anesthetic that potentiates GABA-A receptor activity and inhibits excitatory neurotransmission, resulting in general anesthesia.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ETOMIDATE and ETHRANE depend on the specific clinical indication. These are both General Anesthetic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ETOMIDATE is: Induction: 0.2–0.6 mg/kg IV over 30–60 seconds. Maintenance: 10–20 mcg/kg/min IV continuous infusion.. The standard adult dose of ETHRANE is: 1-5% inspired concentration via inhalation, titrated to effect for maintenance of general anesthesia.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ETOMIDATE and ETHRANE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ETOMIDATE is classified as Category C. Etomidate is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and teratogenicity at doses higher than human doses. There are no adequate and well-co. ETHRANE is classified as Category C. FDA Category B. No evidence of teratogenicity in animal studies; human data limited. Use only if clearly needed during pregnancy, especially first trimester due to potential fetal . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.