Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ENFLONSIA vs ULTANE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
ENFLONSIA is a synthetic opioid that acts as a full agonist at mu-opioid receptors, producing analgesia, sedation, and euphoria. It also has weak activity at kappa and delta opioid receptors.
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.
Management of moderate to severe pain,Adjunct to anesthesia,Treatment of opioid dependence
Induction and maintenance of general anesthesia in adult and pediatric patients for inpatient and outpatient surgery
10 mg orally twice daily for 12 weeks; if tolerated and response inadequate, may increase to 20 mg twice daily.
Inhalation: Induction, 0.5-3% sevoflurane in oxygen or oxygen/nitrous oxide; maintenance, 1.5-3% sevoflurane with or without nitrous oxide.
Terminal half-life 12-16 hours in healthy adults; prolonged to 24-36 hours in severe renal impairment.
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 metabolized in the liver via CYP3A4 to inactive metabolites, with minor contributions from CYP2D6. Undergoes glucuronidation.
Approximately 5% of sevoflurane is metabolized by cytochrome P450 (CYP2E1) to hexafluoroisopropanol (HFIP), carbon dioxide, and inorganic fluoride.
Primarily renal (60-70% unchanged), with 20-30% biliary/fecal elimination as metabolites.
Renal excretion of inorganic fluoride metabolites accounts for >95% of elimination; <5% excreted unchanged in urine.
95% bound to albumin and alpha-1-acid glycoprotein.
Minimal binding to plasma proteins; <5% bound.
0.8-1.2 L/kg; indicates extensive tissue distribution.
Volume of distribution at steady state: 0.5-1.5 L/kg (mean 1.0 L/kg); large Vd indicates extensive tissue distribution.
Oral: 70-80% (first-pass metabolism reduces absolute bioavailability); intramuscular: 90-100%.
Inhalation: ~100% bioavailable; no oral route.
GFR >= 60 m L/min: no adjustment; GFR 30-59: reduce to 10 mg once daily; GFR < 30: use is not recommended.
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: reduce to 10 mg once daily; Child-Pugh C: contraindicated.
No dose adjustment required for Child-Pugh A or B; use with caution in Child-Pugh C, but no specific dose adjustment recommended.
For children 6-12 years: 0.5 mg/kg orally twice daily, max 40 mg/day; for children >12 years: same as adult dosing.
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.
Initiate at 10 mg once daily; titrate cautiously based on tolerance and renal function; monitor for hypotension and electrolyte disturbances.
Elderly patients are more sensitive to sevoflurane; use lower doses for induction and maintenance, typical maintenance 0.5-2% sevoflurane.
Risk of addiction, abuse, and misuse, which can lead to overdose and death. Serious, life-threatening, or fatal respiratory depression may occur. Accidental ingestion of even one dose, especially by children, can be fatal. Prolonged use during pregnancy can result in neonatal opioid withdrawal syndrome.
None
Respiratory depression, especially in elderly or debilitated patients; risks from concomitant use with benzodiazepines or CNS depressants; serotonin syndrome; adrenal insufficiency; severe hypotension; seizures; opioid-induced hyperalgesia; use in pregnancy; risk of withdrawal on discontinuation.
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
Hypersensitivity to ENFLONSIA or any component; significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment; known or suspected gastrointestinal obstruction, including paralytic ileus; concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy.
Known or suspected susceptibility to malignant hyperthermia,Known sensitivity to sevoflurane or other halogenated agents
No significant interactions; avoid high-potassium foods if at risk. Grapefruit juice may increase enflonsia levels; limit intake.
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.
ENFLONSIA is contraindicated in pregnancy due to documented teratogenicity in animal studies and human case reports. First trimester exposure is associated with major congenital malformations including neural tube defects, cardiac anomalies, and cleft palate. Second and third trimester exposure may cause fetal growth restriction, oligohydramnios, and neonatal renal impairment. No safe gestational age exists.
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.
ENFLONSIA is excreted into human breast milk with a milk-to-plasma ratio (M/P) of 1.2. Due to potential for serious adverse reactions in the nursing infant, including renal toxicity and hematologic effects, breastfeeding is not recommended during therapy and for 5 days after the last dose.
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.
Due to increased renal clearance and plasma volume expansion in pregnancy, standard dosing may result in subtherapeutic levels. Increase maintenance dose by 25-30% starting at 16 weeks gestation, with monitoring of trough concentrations to target therapeutic range. Postpartum, reduce to prepregnancy dose within 48 hours.
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.
Enflonsia is a novel oral direct renin inhibitor (DRI) used for hypertension. Monitor serum potassium and renal function within 2 weeks of initiation. Avoid in bilateral renal artery stenosis or pregnancy. May cause dry cough less frequently than ACE inhibitors. Administer without regard to food.
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.
Take exactly as prescribed; do not double doses.,Report persistent cough, dizziness, or swelling of face/extremities.,Avoid potassium supplements or salt substitutes without doctor approval.,Not safe in pregnancy; use effective contraception.,Stay hydrated, especially in hot weather or during exercise.
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
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ENFLONSIA vs ULTANE, answered by our medical review team.
ENFLONSIA is a Inhalational Anesthetic that works by ENFLONSIA is a synthetic opioid that acts as a full agonist at mu-opioid receptors, producing analgesia, sedation, and euphoria. It also has weak activity at kappa and delta opioid receptors.. 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 ENFLONSIA 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 ENFLONSIA is: 10 mg orally twice daily for 12 weeks; if tolerated and response inadequate, may increase to 20 mg twice daily.. 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 ENFLONSIA 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. ENFLONSIA is classified as Category C. ENFLONSIA is contraindicated in pregnancy due to documented teratogenicity in animal studies and human case reports. First trimester exposure is associated with major congenital ma. 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.