Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PENTHRANE vs BILIVIST
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Penthrane (methoxyflurane) is a volatile halogenated ether anesthetic that potentiates GABA-A receptor activity and inhibits NMDA receptors, leading to neuronal hyperpolarization and central nervous system depression. It also sensitizes the myocardium to catecholamines and produces nephrotoxic fluoride ions via metabolism.
Bilivist (gadoxetate disodium) is a hepatobiliary MRI contrast agent. It is taken up by hepatocytes via organic anion transporting polypeptides (OATP1B1/1B3) and excreted into bile via multidrug resistance-associated protein 2 (MRP2). This dual renal and biliary excretion provides both dynamic and hepatocyte-specific imaging.
Induction and maintenance of general anesthesia,Analgesia for short-duration procedures (off-label)
Intravenous use for MRI of the liver to detect and characterize lesions in adults,Off-label: assessment of biliary function, hepatobiliary transit, and bile leak
0.2-0.5% inspired concentration via inhalation for analgesia; for general anesthesia, up to 2% inspired via vaporizer.
0.1 m L/kg (0.25 mmol Gd/kg) intravenously, single dose.
Terminal elimination half-life ranges from 1.5 to 4 hours, reflecting slow washout due to high fat solubility and prolonged release from adipose tissue. Clinically, this can lead to prolonged sedation and risk of fluoride-induced nephrotoxicity.
Terminal elimination half-life approximately 12 hours; clinically relevant for imaging timing and renal function adjustment.
Primarily hepatic via cytochrome P450 enzymes (CYP2E1), releasing inorganic fluoride ions; approximately 50% is metabolized.
Not metabolized. Eliminated via renal (approximately 50%) and biliary (approximately 50%) routes.
Approximately 50% of absorbed methoxyflurane is eliminated unchanged by the lungs; the remainder is metabolized, primarily via hepatic CYP450 isoenzymes, with fluoride ion and other metabolites excreted renally. Biliary/fecal elimination is negligible (<1%).
Primarily renal (glomerular filtration) as unchanged drug; ~95% excreted in urine within 24 hours; <5% biliary/fecal.
40–50% bound to plasma proteins, primarily albumin.
<10% bound to plasma proteins (mainly albumin).
Vd approx 2.0–3.5 L/kg, reflecting extensive distribution into adipose tissue and slow equilibration.
Approximately 0.15–0.20 L/kg; distributes primarily in extracellular fluid.
Inhalation: 100% via pulmonary route (no first-pass metabolism). Not administered orally or parenterally in clinical use.
Not applicable (administered only intravenously); 100% bioavailability by IV route.
No specific GFR-based dose adjustments; use with caution in severe renal impairment due to potential nephrotoxicity from fluoride ions.
Contraindicated in acute kidney injury or chronic severe renal impairment (GFR < 30 m L/min/1.73 m²). No dose adjustment recommended for mild to moderate impairment (GFR ≥ 30 m L/min/1.73 m²).
No specific Child-Pugh based modifications; use with caution in severe hepatic impairment due to potential hepatotoxicity.
No specific dosing adjustment for hepatic impairment; use with caution in severe impairment due to potential gadolinium retention.
Not recommended for children due to risk of nephrotoxicity and hepatotoxicity; alternative agents preferred.
Not approved for patients under 18 years of age; efficacy and safety not established.
Use lower inspired concentrations (e.g., 0.2-0.5%) and monitor closely for hypotension and respiratory depression; consider reduced dose due to decreased renal and hepatic function.
No specific dose adjustment; consider renal function as age-related decline may increase risk of nephrogenic systemic fibrosis (NSF).
Not approved for use in the United States; has been associated with fatal hepatotoxicity and nephrotoxicity, particularly when used at high doses or for prolonged periods.
Gadolinium-based contrast agents increase the risk of nephrogenic systemic fibrosis (NSF) in patients with acute or chronic severe renal insufficiency (glomerular filtration rate <30 m L/min/1.73m²) or acute kidney injury due to hepatorenal syndrome or in the perioperative liver transplantation period.
Hepatotoxicity and nephrotoxicity due to fluoride ion accumulation; myocardial sensitization to catecholamines; malignant hyperthermia risk; respiratory depression; dose-dependent renal impairment.
Risk of nephrogenic systemic fibrosis in patients with severe renal impairment,Hypersensitivity reactions including anaphylaxis,Acute kidney injury risk in patients with preexisting renal impairment,Injection site reactions, extravasation,Potential for false-positive diagnostic interpretation
Hypersensitivity to halogenated anesthetics; known or suspected susceptibility to malignant hyperthermia; significant hepatic or renal impairment; concurrent use of nephrotoxic agents.
History of hypersensitivity to gadoxetate disodium or any gadolinium-based contrast agent,Severe renal insufficiency (GFR <30 m L/min/1.73m²)
No direct food interactions are documented. However, methoxyflurane metabolism may be affected by hepatic enzyme inducers or inhibitors. Avoid excessive consumption of grapefruit juice as it may inhibit CYP2E1, potentially altering drug metabolism. Maintain adequate hydration to help reduce the risk of nephrotoxicity.
No specific food interactions. Fasting is not required. Encourage hydration before and after administration to promote renal elimination.
First trimester: Limited human data; animal studies show fetal toxicity at high doses. Potential risk of congenital anomalies cannot be excluded. Second and third trimesters: May cause fetal hypotension and bradycardia; avoid prolonged or high-dose exposure. Near term: Risk of neonatal respiratory depression.
BILIVIST (gadoxetate disodium) is a gadolinium-based contrast agent (GBCA). Gadolinium crosses the placenta and accumulates in fetal tissues. There are no adequate studies in pregnant women; however, animal studies have shown adverse effects at high doses. The risk of nephrogenic systemic fibrosis (NSF) from gadolinium exposure is theoretical in the fetus. Use in pregnancy only if clearly needed and after careful risk-benefit assessment. The highest risk is in the first trimester during organogenesis, but the agent should be avoided in all trimesters unless essential.
Unknown if excreted in human milk. M/P ratio not established. Caution advised; consider benefits of breastfeeding vs. potential risk to infant.
It is unknown whether gadoxetate disodium is excreted in human breast milk. Other GBCAs are excreted in very low amounts (less than 0.04% of the maternal dose) with milk-to-plasma ratios around 0.04. The risk to the nursing infant is likely minimal. However, caution is advised; a 24-hour period of breastfeeding interruption can be considered to reduce exposure. The M/P ratio is not specifically reported for BILIVIST.
No specific dose adjustments recommended due to limited data. Pharmacokinetic changes in pregnancy (increased volume of distribution, clearance) may reduce efficacy; use lowest effective dose for shortest duration.
No pharmacokinetic studies specifically in pregnancy are available. However, pregnancy does alter renal function (increased GFR), which may increase gadoxetate clearance. No dose adjustment is recommended; standard adult dose (0.025 mmol/kg body weight) is used if the exam is deemed necessary. Due to unknown risks, the lowest effective dose should be used.
Penthrane (methoxyflurane) is a volatile inhalational anesthetic with potent analgesic properties at subanesthetic doses. It is primarily used for emergency pain relief via a handheld inhaler (Penthrox). Key clinical pearls: (1) Nephrotoxicity is dose-dependent due to inorganic fluoride metabolites; limit exposure to a maximum of 6 m L over a week. (2) Avoid concurrent use of tetracyclines or aminoglycosides due to increased nephrotoxic risk. (3) Caution in patients with renal impairment, hepatic disease, or malignant hyperthermia susceptibility. (4) Rapid onset of analgesia within 2-5 breaths; monitor for excessive sedation or respiratory depression. (5) Do not use in patients with cardiovascular instability or hypovolemia as it can cause myocardial depression.
BILIVIST (gadoxetate disodium) is a hepatobiliary MRI contrast agent used for focal liver lesion detection. Its dual elimination (renal and biliary) allows for dynamic and hepatobiliary phase imaging. Administer as a bolus at 0.025 mmol/kg. Transient dyspnea or respiratory distress may occur during injection; monitor patient. Use with caution in severe renal impairment (e GFR <30 m L/min) due to risk of nephrogenic systemic fibrosis. Avoid rapid injection; preferred rate is 1 m L/sec.
Penthrane is used to relieve moderate to severe pain from trauma or procedures.,Inhale from the device as instructed; do not swallow the liquid.,You may feel drowsy or dizzy; avoid driving or operating machinery for at least 24 hours after use.,Do not consume alcohol or take other central nervous system depressants without consulting your doctor.,Report any signs of kidney injury such as decreased urination, swelling, or fatigue.,Use only as directed and do not exceed the prescribed dose or duration.,Keep the inhaler out of reach of children and do not share with others.
This medication is given intravenously before an MRI to help visualize liver lesions.,Inform your doctor if you have kidney disease, diabetes, or previous allergic reactions to contrast agents.,You may experience a brief sensation of shortness of breath or chest tightness during injection; this usually resolves quickly.,Drink plenty of water before and after the procedure to help eliminate the contrast agent.,Tell your doctor if you are pregnant, breastfeeding, or planning to become pregnant.
No interactions on record
No interactions on record
Common clinical questions about PENTHRANE vs BILIVIST, answered by our medical review team.
PENTHRANE is a Inhaled Anesthetic that works by Penthrane (methoxyflurane) is a volatile halogenated ether anesthetic that potentiates GABA-A receptor activity and inhibits NMDA receptors, leading to neuronal hyperpolarization and central nervous system depression. It also sensitizes the myocardium to catecholamines and produces nephrotoxic fluoride ions via metabolism.. BILIVIST is a Contrast Agent (Hepatobiliary) that works by Bilivist (gadoxetate disodium) is a hepatobiliary MRI contrast agent. It is taken up by hepatocytes via organic anion transporting polypeptides (OATP1B1/1B3) and excreted into bile via multidrug resistance-associated protein 2 (MRP2). This dual renal and biliary excretion provides both dynamic and hepatocyte-specific imaging.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PENTHRANE and BILIVIST 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 PENTHRANE is: 0.2-0.5% inspired concentration via inhalation for analgesia; for general anesthesia, up to 2% inspired via vaporizer.. The standard adult dose of BILIVIST is: 0.1 m L/kg (0.25 mmol Gd/kg) intravenously, single dose.. 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 PENTHRANE and BILIVIST 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. PENTHRANE is classified as Category C. First trimester: Limited human data; animal studies show fetal toxicity at high doses. Potential risk of congenital anomalies cannot be excluded. Second and third trimesters: May c. BILIVIST is classified as Category C. BILIVIST (gadoxetate disodium) is a gadolinium-based contrast agent (GBCA). Gadolinium crosses the placenta and accumulates in fetal tissues. There are no adequate studies in pregn. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.