Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ETOMIDATE vs TENUATE
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.
Tenuate (diethylpropion) is a sympathomimetic amine that acts as an appetite suppressant. It stimulates the release of norepinephrine and to a lesser extent dopamine from presynaptic nerve terminals in the hypothalamus, increasing satiety.
Induction of general anesthesia,Procedural sedation (off-label),Rapid sequence intubation (off-label)
FDA-approved: short-term (up to 12 weeks) adjunct in a regimen of weight reduction based on caloric restriction in patients with exogenous obesity.,Off-label: long-term management of obesity (not FDA-approved for extended use).
Induction: 0.2–0.6 mg/kg IV over 30–60 seconds. Maintenance: 10–20 mcg/kg/min IV continuous infusion.
25 mg orally three times daily before meals, or 75 mg extended-release orally once daily in the morning.
Terminal elimination half-life: 2.9–5.3 hours (context: redistribution shortens clinical effect; hepatic impairment prolongs).
4-6 hours (terminal); clinical context: short half-life supports multiple daily dosing
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.
Extensively metabolized in the liver via N-dealkylation to active metabolites (ethylaminopropiophenone and diethylaminopropiophenone). Enzymes involved include CYP3A4 and CYP2D6.
Renal: 75% as metabolite (carboxylic acid), 2% unchanged; fecal/biliary: minimal.
Renal (90% as metabolites, ~10% unchanged); minor biliary/fecal (<10%)
76% bound to albumin.
~92% (primarily albumin)
Vd: 2.5–4.5 L/kg (large, indicating extensive tissue uptake).
~4 L/kg (extensive tissue distribution, including CNS)
IV: 100% (only route used clinically).
Oral: ~60-70% (first-pass metabolism)
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 specific guidelines; use with caution in severe renal impairment (GFR <30 m L/min) due to potential accumulation.
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.
Contraindicated in Child-Pugh Class C; use with caution in Class A and B, consider dose reduction.
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.
Not recommended for children under 16 years of age.
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.
Initial dose at 12.5 mg twice daily; titrate slowly due to increased sensitivity and risk of adverse effects.
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.)
There is no FDA boxed warning for Tenuate.
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)
Primary pulmonary hypertension: rare but serious condition associated with use.,Cardiac valvulopathy: risk increases with prolonged use or combination with other serotonergic drugs.,Tachyphylaxis: tolerance to anorectic effects may develop within a few weeks.,Psychiatric effects: may exacerbate psychiatric disorders, particularly in patients with history of substance abuse.,Seizures: risk increased in patients with epilepsy or history of seizures.
Hypersensitivity to etomidate,Patients with acute porphyria (may be porphyrinogenic)
Hypersensitivity to diethylpropion or other sympathomimetic amines.,Advanced arteriosclerosis, cardiovascular disease, moderate to severe hypertension, hyperthyroidism, glaucoma.,History of drug abuse, agitated states.,Concurrent use (or within 14 days of discontinuing) MAO inhibitors (hypertensive crisis risk).
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.
Avoid caffeine and other stimulants (e.g., in coffee, tea, cola, energy drinks) as they may increase cardiovascular side effects. Avoid high-tyramine foods (e.g., aged cheeses, cured meats, fermented products) if also taking MAOIs, but this is relevant only if transitioning therapy. No specific food restrictions otherwise, but a reduced-calorie diet is essential for efficacy.
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.
First trimester: Limited human data, but animal studies suggest increased risk of cardiovascular and neural tube defects. Second and third trimesters: Associated with reduced fetal growth and neonatal withdrawal symptoms (tremors, hypertonia, feeding difficulties). Avoid use unless clearly needed.
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 human milk; M/P ratio not determined. Potential for adverse effects in nursing infants (e.g., irritability, poor weight gain). Use caution; decision to discontinue nursing or drug based on importance to mother.
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 pharmacokinetic data; however, pregnancy may alter metabolism. Start with lowest effective dose (25 mg BID) and monitor clinical response. Avoid sustained-release formulations due to altered GI transit.
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.
Tenuate (diethylpropion) is a sympathomimetic amine anorectic indicated for short-term (8-12 weeks) adjunct in obesity management. Avoid in patients with history of drug abuse, cardiovascular disease, hyperthyroidism, or glaucoma. Monitor blood pressure and heart rate regularly. Tolerance may develop; discontinue if tolerance occurs. Contraindicated with MAOIs or within 14 days of their use. May impair ability to drive or operate machinery.
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.
Take exactly as prescribed; do not increase dose or duration.,May cause dizziness or blurred vision; avoid driving if affected.,Inform your doctor if you have heart disease, high blood pressure, or thyroid problems.,Avoid alcohol and other CNS stimulants while taking this medication.,Report any chest pain, palpitations, or severe headache immediately.,Do not take with other appetite suppressants without consulting your doctor.,This medication is only for short-term use; combine with diet and exercise.
"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 TENUATE, 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.. TENUATE is a Sympathomimetic anorectic that works by Tenuate (diethylpropion) is a sympathomimetic amine that acts as an appetite suppressant. It stimulates the release of norepinephrine and to a lesser extent dopamine from presynaptic nerve terminals in the hypothalamus, increasing satiety.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ETOMIDATE and TENUATE depend on the specific clinical indication. These are agents from distinct pharmacological classes 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 TENUATE is: 25 mg orally three times daily before meals, or 75 mg extended-release orally once daily in the morning.. 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 TENUATE 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. TENUATE is classified as Category C. First trimester: Limited human data, but animal studies suggest increased risk of cardiovascular and neural tube defects. Second and third trimesters: Associated with reduced fetal. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.