Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
KETALAR vs ETOMIDATE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Noncompetitive NMDA receptor antagonist; inhibits glutamate activity, modulates opioid receptors, and interacts with other neurotransmitter systems.
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.
Induction and maintenance of general anesthesia,Procedural sedation and analgesia,Treatment of refractory status epilepticus (off-label),Major depressive disorder with suicidal ideation (off-label)
Induction of general anesthesia,Procedural sedation (off-label),Rapid sequence intubation (off-label)
1-4.5 mg/kg IV or 6.5-13 mg/kg IM for induction of anesthesia; 0.1-0.5 mg/kg/min IV infusion for maintenance.
Induction: 0.2–0.6 mg/kg IV over 30–60 seconds. Maintenance: 10–20 mcg/kg/min IV continuous infusion.
Terminal elimination half-life: 2.5-3 hours (ketamine); norketamine: 12 hours. Clinical context: Short half-life facilitates rapid recovery, but context-sensitive half-life increases with infusion duration.
Terminal elimination half-life: 2.9–5.3 hours (context: redistribution shortens clinical effect; hepatic impairment prolongs).
Primarily hepatic via N-demethylation by CYP3A4 and CYP2B6 to norketamine, then further metabolized via hydroxylation and conjugation.
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.
Renal: 90% as metabolites (norketamine, dehydronorketamine); unchanged: 2-4%. Fecal: <3%.
Renal: 75% as metabolite (carboxylic acid), 2% unchanged; fecal/biliary: minimal.
12-50% primarily to albumin and alpha-1-acid glycoprotein.
76% bound to albumin.
1-2 L/kg (large, indicating extensive tissue distribution). Highly lipophilic, crosses blood-brain barrier rapidly.
Vd: 2.5–4.5 L/kg (large, indicating extensive tissue uptake).
Oral: 16-24% (extensive first-pass metabolism); Intranasal: 45-50%; IM: 93%; Subcutaneous: 100%.
IV: 100% (only route used clinically).
No dose adjustment required for GFR >10 m L/min; for GFR <10 m L/min, consider dose reduction by 50% due to accumulation of active metabolite norketamine.
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.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use or use with extreme caution, reduce dose by 75%.
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.
Induction: 1-2 mg/kg IV or 4-6 mg/kg IM; maintenance: 0.5-1 mg/kg IV boluses or 10-50 mcg/kg/min IV infusion. Titrate to effect.
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.
Reduce initial dose by 50% (e.g., 0.5-2 mg/kg IV) and titrate slowly due to increased sensitivity and risk of delirium; consider lower infusion rates (0.1-0.3 mg/kg/min).
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.
Hemodynamic instability (hypertension, tachycardia) and increased intracranial pressure; risk of emergent reactions (hallucinations, delirium); potential for abuse and dependence.
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.)
Monitor blood pressure and cardiac function; use with caution in patients with hypertension, heart failure, or increased intracranial pressure; emergence reactions may occur; laryngospasm risk; respiratory depression.
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)
Hypersensitivity to ketamine; conditions where elevated blood pressure or intracranial pressure would be dangerous (e.g., severe hypertension, cerebral hemorrhage); severe coronary artery disease; history of psychotic disorders.
Hypersensitivity to etomidate,Patients with acute porphyria (may be porphyrinogenic)
No specific food interactions; avoid alcohol for 24 hours due to additive CNS depression.
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.
First trimester: Limited human data; animal studies show no teratogenicity. Second/third trimester: Use only if clearly needed; may cause neonatal respiratory depression, hypotonia, and altered neurobehavior if used near delivery.
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.
Excreted into breast milk in low amounts; M/P ratio unknown. Use caution, especially with repeated doses or in neonates with hepatic impairment.
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.
No specific dose adjustment required for pregnancy; consider reduced dose due to increased volume of distribution and clearance in late pregnancy. Use lowest effective dose.
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.
Ketamine (Ketalar) produces dissociative anesthesia with potent analgesia. Onset of action is rapid (30 seconds IV, 5 minutes IM). Emergence reactions (hallucinations, delirium) can be mitigated with benzodiazepines. Contraindicated in patients with hypertension, aneurysms, or increased intracranial pressure due to sympathomimetic effects. Use with caution in patients with psychosis or thyroid disorders.
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.
You may experience vivid dreams or hallucinations as the medication wears off; this is common and can be reduced with other medications.,Do not drive, operate machinery, or make important decisions for at least 24 hours after receiving ketamine.,Avoid alcohol and other sedatives for 24 hours after administration.,Inform your healthcare provider if you have high blood pressure, heart disease, or a history of psychosis.
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.
No interactions on record
"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."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about KETALAR vs ETOMIDATE, answered by our medical review team.
KETALAR is a General Anesthetic that works by Noncompetitive NMDA receptor antagonist; inhibits glutamate activity, modulates opioid receptors, and interacts with other neurotransmitter systems.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between KETALAR and ETOMIDATE 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 KETALAR is: 1-4.5 mg/kg IV or 6.5-13 mg/kg IM for induction of anesthesia; 0.1-0.5 mg/kg/min IV infusion for maintenance.. 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.. 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 KETALAR and ETOMIDATE 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. KETALAR is classified as Category C. First trimester: Limited human data; animal studies show no teratogenicity. Second/third trimester: Use only if clearly needed; may cause neonatal respiratory depression, hypotonia. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.