Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
KETAMINE HYDROCHLORIDE vs ETHRANE
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; also interacts with opioid receptors, monoaminergic receptors, and voltage-gated calcium channels.
Enflurane is a volatile inhalational anesthetic that potentiates GABA-A receptor activity and inhibits excitatory neurotransmission, resulting in general anesthesia.
Induction and maintenance of general anesthesia,Sedation,Analgesic for acute pain,Treatment-resistant depression (off-label),Status epilepticus (off-label)
Induction and maintenance of general anesthesia
Induction: 1-2 mg/kg IV, 0.5-1 mg/kg/min IV infusion for maintenance. Dissociative sedation: 1-1.5 mg/kg IV or 3-4 mg/kg IM. Pain management: 0.1-0.5 mg/kg IV bolus followed by 0.1-0.4 mg/kg/h IV infusion.
1-5% inspired concentration via inhalation, titrated to effect for maintenance of general anesthesia.
Terminal elimination half-life of ketamine is 2.5–3 hours; norketamine half-life is approximately 4 hours. Context: Prolonged elimination may occur with hepatic impairment or high-dose infusions.
Context-sensitive half-life: approximately 2-5 minutes after short procedures; prolonged after prolonged administration due to slow washout from fat stores.
Hepatic via CYP2B6 and CYP3A4; major metabolite norketamine.
Primarily hepatic via cytochrome P450 (CYP2E1); minor metabolism to fluoride ions.
Ketamine is primarily metabolized in the liver via N-demethylation to norketamine. Renal excretion accounts for approximately 90% of the dose, with 4% as unchanged drug, 16% as norketamine, and the remainder as conjugated metabolites. Fecal excretion is minimal (<5%).
Primarily exhaled unchanged via lungs (>95%); less than 5% metabolized in liver to fluoride ion and other metabolites, with renal excretion of metabolites.
Approximately 47% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
Approximately 30-40%, primarily to albumin.
Volume of distribution is 3–5 L/kg, indicating extensive tissue distribution and accumulation in lipid-rich tissues (e.g., brain, adipose).
Vd: 1.2-2.0 L/kg, indicating extensive distribution into tissues, especially fat.
Oral: 17–20% (extensive first-pass metabolism); Intranasal: 45–50%; IM: 93%; Rectal: 25–50%; IV: 100%.
By inhalation: 100% as delivered; not administered orally.
No specific GFR-based dose adjustment is required. Use with caution in severe renal impairment (Cr Cl <30 m L/min) due to potential accumulation of active metabolite norketamine; monitor for prolonged effects.
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.
Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 25-50% and titrate to effect. Child-Pugh Class C: Contraindicated or use with extreme caution; reduce dose by 50-75% and monitor closely.
No specific Child-Pugh based adjustment; use with caution in severe hepatic impairment as metabolism may be decreased.
Induction: 1-2 mg/kg IV, 3-4 mg/kg IM. Maintenance: 0.5-1 mg/kg IV or IM as needed. Procedural sedation: 0.5-1 mg/kg IV, may repeat. Continuous infusion: 0.2-0.5 mg/kg/h. Maximum single dose: 2 mg/kg IV, 4 mg/kg IM.
Induction: 2-5% inspired concentration; Maintenance: 1-3% inspired concentration, adjusted to age and response.
Reduce initial dose by 20-50% due to decreased clearance and increased sensitivity. Titrate slowly to effect. Monitor for cardiovascular and cognitive adverse effects closely.
Lower inspired concentrations (0.5-2%) recommended due to increased sensitivity and reduced clearance; titrate to effect.
None.
None
Emergence reactions (hallucinations, confusion),Hemodynamic instability (hypertension, tachycardia),Increased intracranial pressure,Respiratory depression,Urinary tract toxicity with chronic use
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 ketamine,Conditions where elevated blood pressure is dangerous (e.g., aneurysms, uncontrolled hypertension),Severe coronary artery disease,Increased intracranial pressure (relative)
Known hypersensitivity to enflurane or other halogenated anesthetics,Known or suspected susceptibility to malignant hyperthermia,Severe hepatic impairment,Uncontrolled epilepsy
No significant food interactions; grapefruit juice may increase ketamine levels via CYP3A4 inhibition, but clinical relevance is unclear; avoid alcohol consumption due to additive sedative effects.
No specific food interactions. Patient must follow preoperative fasting guidelines (nil per os, NPO) as directed by anesthesiologist to reduce risk of aspiration.
Ketamine crosses the placenta. First trimester: Limited human data, animal studies show developmental toxicity at high doses; avoid unless essential. Second/Third trimester: Use only for indicated procedures (e.g., surgical anesthesia, procedural sedation) as maternal hypoxia may risk fetus; potential for neonatal respiratory depression if used near delivery. Neonatal effects: Possible altered neurodevelopment; consider risk-benefit.
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.
Ketamine enters breast milk; milk-to-plasma ratio approximately 0.8-1.5. Limited data; low absolute dose (<2% maternal weight-adjusted dose). Caution with repeated high doses; monitor infant for sedation, feeding difficulties. American Academy of Pediatrics: compatible with breastfeeding after single doses.
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.
Pregnancy may alter pharmacokinetics: increased volume of distribution may require higher initial doses; decreased plasma protein binding may increase free fraction. However, standard dosing guidelines for procedures apply; titrate to effect. Use lowest effective dose due to potential neurotoxicity. Caution with repeated use or long infusions.
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.
Ketamine produces dissociative anesthesia with preserved airway reflexes and respiratory drive at sub-anesthetic doses; monitor for emergence reactions (hallucinations, delirium) especially in adults; co-administer a benzodiazepine to reduce psychotomimetic effects; use with caution in patients with hypertension, tachycardia, or increased intracranial pressure; can cause increased secretions, consider an anticholinergic like glycopyrrolate; analgesic doses are sub-dissociative (0.1-0.5 mg/kg IV); contraindicated in patients with severe coronary artery disease or recent cerebrovascular accident.
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 feel detached from your body or have unusual dreams during recovery; this is normal and temporary.,Do not drive or operate machinery for 24 hours after receiving ketamine.,Avoid alcohol and other sedatives for at least 24 hours after treatment.,Report any hallucinations, confusion, or difficulty breathing to your healthcare provider immediately.,For nasal spray (esketamine), follow instructions for administration and avoid eating or drinking for 30 minutes after use.
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.
"Butabarbital, a barbiturate, induces cytochrome P450 (CYP) enzymes, enhancing the hepatic metabolism of ketamine, a dissociative anesthetic primarily metabolized by CYP3A4 and CYP2B6. This interaction reduces ketamine's systemic exposure and anesthetic efficacy, potentially leading to suboptimal sedation or anesthesia. Additionally, concurrent use may increase the risk of respiratory depression and hypotension due to additive central nervous system (CNS) depressant effects."
"The combination of ketamine and diamorphine can lead to additive central nervous system (CNS) depression and respiratory depression, increasing the risk of hypoxia, sedation, and respiratory arrest. Ketamine, an NMDA receptor antagonist, enhances opioid-induced analgesia but also potentiates the adverse effects of diamorphine, including hypotension and bradycardia. Patients may experience profound sedation, confusion, and cardiovascular instability, particularly at higher doses or in opioid-naive individuals."
"Ketamine, an NMDA receptor antagonist, may inhibit cytochrome P450 3A4 (CYP3A4) activity, which is responsible for the 25-hydroxylation of cholecalciferol (vitamin D3) to calcidiol (25-hydroxyvitamin D). This inhibition can reduce the conversion of cholecalciferol to its active form, potentially leading to decreased vitamin D levels and impaired calcium homeostasis. Clinically, this may increase the risk of vitamin D deficiency, contributing to bone demineralization, hypocalcemia, or secondary hyperparathyroidism in patients receiving long-term or high-dose ketamine therapy."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about KETAMINE HYDROCHLORIDE vs ETHRANE, answered by our medical review team.
KETAMINE HYDROCHLORIDE is a General Anesthetic that works by Noncompetitive NMDA receptor antagonist; also interacts with opioid receptors, monoaminergic receptors, and voltage-gated calcium channels.. 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 KETAMINE HYDROCHLORIDE 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 KETAMINE HYDROCHLORIDE is: Induction: 1-2 mg/kg IV, 0.5-1 mg/kg/min IV infusion for maintenance. Dissociative sedation: 1-1.5 mg/kg IV or 3-4 mg/kg IM. Pain management: 0.1-0.5 mg/kg IV bolus followed by 0.1-0.4 mg/kg/h IV 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 KETAMINE HYDROCHLORIDE 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. KETAMINE HYDROCHLORIDE is classified as Category C. Ketamine crosses the placenta. First trimester: Limited human data, animal studies show developmental toxicity at high doses; avoid unless essential. Second/Third trimester: Use on. 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.