Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ENFLURANE vs ULTANE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Enflurane is a volatile halogenated ether that potentiates GABA-A receptor activity, inhibits NMDA receptors, and enhances glycine receptor function, leading to generalized central nervous system depression and anesthesia.
Sevoflurane is a volatile general anesthetic that enhances inhibitory neurotransmission via GABA-A and glycine receptors, and inhibits excitatory neurotransmission via NMDA and nicotinic acetylcholine receptors, producing anesthesia, amnesia, and muscle relaxation.
Induction and maintenance of general anesthesia,Supplement to nitrous oxide and oxygen anesthesia
Induction and maintenance of general anesthesia in adult and pediatric patients for inpatient and outpatient surgery
Induction: 0.5-4.5% inspired concentration; Maintenance: 0.5-3% inspired concentration with oxygen/nitrous oxide; via inhalation.
Inhalation: Induction, 0.5-3% sevoflurane in oxygen or oxygen/nitrous oxide; maintenance, 1.5-3% sevoflurane with or without nitrous oxide.
Terminal elimination half-life is approximately 4-8 hours in adults; context: prolonged with obesity due to high lipid solubility and storage in adipose tissue.
Terminal elimination half-life of inorganic fluoride is approximately 2-5 hours (mean 3.0 h) in adults; context: prolonged with obesity or renal impairment.
Primarily hepatic via cytochrome P450 (CYP2E1); approximately 2% undergoes oxidative metabolism to difluoromethoxy-difluoroacetic acid and fluoride ions; rest is excreted unchanged by lungs.
Approximately 5% of sevoflurane is metabolized by cytochrome P450 (CYP2E1) to hexafluoroisopropanol (HFIP), carbon dioxide, and inorganic fluoride.
Primarily eliminated by pulmonary excretion as unchanged drug (>90%); less than 5% is metabolized via CYP2E1 to fluoride ions and other metabolites, which are renally excreted.
Renal excretion of inorganic fluoride metabolites accounts for >95% of elimination; <5% excreted unchanged in urine.
Approximately 55-75% bound to serum proteins, primarily albumin and alpha-1-acid glycoprotein.
Minimal binding to plasma proteins; <5% bound.
Volume of distribution at steady state (Vdss) is approximately 3.5-4.5 L/kg, indicating extensive tissue distribution and lipid solubility.
Volume of distribution at steady state: 0.5-1.5 L/kg (mean 1.0 L/kg); large Vd indicates extensive tissue distribution.
Inhalation: Bioavailability is essentially 100% as administered via inhalation, with rapid absorption across the alveolar-capillary barrier.
Inhalation: ~100% bioavailable; no oral route.
No specific GFR-based dose adjustment required; however, monitor for nephrotoxicity in severe renal impairment (e GFR <30 m L/min) due to potential fluoride ion accumulation.
No dose adjustment required for GFR ≥30 m L/min; use with caution in GFR <30 m L/min due to potential for elevated fluoride concentrations, but no specific dose adjustment recommended.
Child-Pugh A: no adjustment; Child-Pugh B: use with caution, reduce concentration; Child-Pugh C: avoid due to risk of hepatotoxicity and altered metabolism.
No dose adjustment required for Child-Pugh A or B; use with caution in Child-Pugh C, but no specific dose adjustment recommended.
Induction: 1-4% inspired concentration; Maintenance: 0.5-2% inspired concentration; adjust based on age and response.
Induction: 2-4% sevoflurane in oxygen or oxygen/nitrous oxide, up to 8% for mask induction; maintenance: 1.5-3% with or without nitrous oxide.
Reduce inspired concentration by 25-50% due to decreased minimal alveolar concentration (MAC) and increased sensitivity; monitor hemodynamics closely.
Elderly patients are more sensitive to sevoflurane; use lower doses for induction and maintenance, typical maintenance 0.5-2% sevoflurane.
None
None
May cause dose-dependent respiratory and cardiovascular depression,Risk of seizures (especially with deep anesthesia or hypocarbia),Potential for hepatotoxicity (rare, but caution in patients with pre-existing liver disease),Malignant hyperthermia risk,Should not be used in patients with known sensitivity to halogenated anesthetics
Risk of malignant hyperthermia; may cause respiratory depression; caution in patients with preexisting respiratory or cardiovascular disease; monitor for hepatotoxicity; use with caution in patients with renal impairment (elevated fluoride levels); sevoflurane may cause QT prolongation
Known hypersensitivity to enflurane or other halogenated anesthetics,Known or suspected genetic susceptibility to malignant hyperthermia,Severe hypotension or hypovolemia (relative),Prior history of hepatitis after halothane or other halogenated agents (relative)
Known or suspected susceptibility to malignant hyperthermia,Known sensitivity to sevoflurane or other halogenated agents
No specific food interactions known for enflurane. Avoid alcohol for at least 24 hours post-anesthesia as it may increase sedation and hepatotoxicity risk.
No specific food interactions with sevoflurane. However, patients should adhere to preoperative fasting guidelines (typically 6-8 hours for solids, 2 hours for clear liquids) to reduce aspiration risk during anesthesia.
Enflurane is not recommended during the first and second trimesters due to potential teratogenicity based on animal studies showing fetal malformations. During the third trimester, use is avoided for elective procedures as it may cause uterine relaxation and fetal depression. Risk is dose-dependent and duration-dependent.
Sevoflurane (ULTANE) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated teratogenic or fetotoxic effects at clinically relevant doses. In humans, limited data do not indicate an increased risk of major malformations with first-trimester exposure. However, use during the second and third trimesters may cause transient neonatal depression, including hypotonia and respiratory depression, due to placental transfer. Prolonged or repeated exposure should be avoided, especially during organogenesis, as with all volatile anesthetics.
Enflurane is excreted into breast milk in low concentrations. The M/P ratio is not well established but estimated around 0.5-1.0. Because of rapid clearance and minimal oral bioavailability, a single exposure is considered compatible with breastfeeding after waiting 24 hours. No adverse effects reported in infants.
Sevoflurane is excreted into breast milk in low quantities. The milk-to-plasma (M/P) ratio has not been specifically determined for sevoflurane, but based on physicochemical properties, it is expected to be low. Due to rapid clearance and low oral bioavailability, the risk to a nursing infant is considered minimal after a single anesthetic dose. However, it is recommended to express and discard breast milk for 24 hours after anesthesia to minimize infant exposure.
Pregnancy may decrease MAC (minimum alveolar concentration) by up to 40% due to progesterone and endogenous opioids. Dose should be reduced accordingly. No specific dose adjustment based on pharmacokinetic changes, but careful titration to effect is required.
During pregnancy, pharmacokinetic changes such as increased plasma volume, decreased protein binding, and increased cardiac output may necessitate dose adjustments. Sevoflurane requirements may be reduced by approximately 25-30% during pregnancy due to increased sensitivity to volatile anesthetics and decreased minimum alveolar concentration (MAC). Induction and maintenance doses should be titrated to effect, with close hemodynamic monitoring to avoid hypotension. No specific dose reduction is mandated, but careful titration is recommended.
Enflurane is a potent inhalation anesthetic that can cause dose-dependent myocardial depression and hypotension. It sensitizes the myocardium to catecholamines, increasing arrhythmia risk. Enflurane may provoke seizure activity at high concentrations or with hypocapnia. Malignant hyperthermia trigger. Use caution in patients with hepatic or renal impairment due to fluoride ion release.
ULTANE (sevoflurane) is a volatile anesthetic with low blood-gas solubility, facilitating rapid induction and emergence. It is associated with a risk of malignant hyperthermia; have dantrolene available. Sevoflurane can degrade in carbon dioxide absorbents to compound A, which may cause renal injury; use fresh gas flows ≥2 L/min to minimize this risk. Monitor end-tidal sevoflurane concentration closely, as hypotension and respiratory depression are dose-dependent.
You will be unconscious and feel no pain during surgery.,You may experience nausea or shivering after waking up.,Inform your anesthesiologist if you have a personal or family history of malignant hyperthermia.,Avoid operating machinery or driving for at least 24 hours after anesthesia.,Report any unusual muscle stiffness, fever, or dark urine after surgery.
You will receive this medication only under the supervision of an anesthesia professional,Do not eat or drink before surgery as instructed by your doctor,You may experience dizziness or drowsiness after waking; do not drive for 24 hours,Report any history of kidney disease or adverse reactions to anesthesia,Inform your doctor if you are pregnant or breastfeeding,You will be monitored throughout the procedure for vital signs and safety
"Enflurane, a halogenated volatile anesthetic, and venlafaxine, a serotonin-norepinephrine reuptake inhibitor (SNRI), both inhibit neuronal reuptake of monoamines, leading to increased central nervous system (CNS) levels of serotonin and norepinephrine. Concurrent use may potentiate the risk of serotonin syndrome, characterized by agitation, hyperthermia, autonomic instability, and neuromuscular hyperactivity. Additionally, venlafaxine can lower the seizure threshold, while enflurane may produce epileptiform EEG activity, raising the potential for perioperative seizures."
"Enflurane is a halogenated volatile anesthetic that potentiates the effects of gamma-aminobutyric acid (GABA) at GABA-A receptors, leading to central nervous system (CNS) depression. Tiapride, a selective dopamine D2 receptor antagonist, can also cause CNS depression and prolong the QT interval. Combined use may result in additive CNS depression, increasing the risk of excessive sedation, respiratory depression, and hypotension. Additionally, both drugs can lower the seizure threshold, potentially increasing the risk of perioperative seizures."
"The combination of enflurane and levobupivacaine increases the risk of cardiotoxicity and central nervous system (CNS) toxicity. Enflurane sensitizes the myocardium to the arrhythmogenic effects of levobupivacaine, potentially leading to severe ventricular arrhythmias. Additionally, both drugs depress myocardial contractility and conduction, which may result in hypotension, bradycardia, or cardiac arrest."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ENFLURANE vs ULTANE, answered by our medical review team.
ENFLURANE is a Inhalational Anesthetic that works by Enflurane is a volatile halogenated ether that potentiates GABA-A receptor activity, inhibits NMDA receptors, and enhances glycine receptor function, leading to generalized central nervous system depression and anesthesia.. ULTANE is a Inhalational Anesthetic that works by Sevoflurane is a volatile general anesthetic that enhances inhibitory neurotransmission via GABA-A and glycine receptors, and inhibits excitatory neurotransmission via NMDA and nicotinic acetylcholine receptors, producing anesthesia, amnesia, and muscle relaxation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ENFLURANE and ULTANE depend on the specific clinical indication. These are both Inhalational 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 ENFLURANE is: Induction: 0.5-4.5% inspired concentration; Maintenance: 0.5-3% inspired concentration with oxygen/nitrous oxide; via inhalation.. The standard adult dose of ULTANE is: Inhalation: Induction, 0.5-3% sevoflurane in oxygen or oxygen/nitrous oxide; maintenance, 1.5-3% sevoflurane with or without nitrous oxide.. 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 ENFLURANE and ULTANE 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. ENFLURANE is classified as Category C. Enflurane is not recommended during the first and second trimesters due to potential teratogenicity based on animal studies showing fetal malformations. During the third trimester,. ULTANE is classified as Category C. Sevoflurane (ULTANE) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated teratogenic or fetotoxic effects at clinically relevant doses. In humans, limit. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.