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Isoflurane: Drug information

Isoflurane: Drug information
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For additional information see "Isoflurane: Patient drug information"

For abbreviations, symbols, and age group definitions show table
Brand Names: US
  • Forane;
  • Terrell
Pharmacologic Category
  • General Anesthetic, Inhalation
Dosing: Adult

Note: Coughing, breath-holding, bronchospasm, or laryngospasm may occur during induction; use of an ultra short-acting barbiturate may avoid these symptoms. Minimum alveolar concentration of isoflurane decreases with increasing patient age. Select premedication according to the need of the individual patient, taking into account that secretions are weakly stimulated by isoflurane, and the heart rate tends to be increased. Dosage must be individualized based on patient response.

Anesthesia

Anesthesia: Inhalation:

Induction: 1.5% to 3% isoflurane with oxygen or oxygen-nitrous oxide mixture.

Maintenance: With nitrous oxide: 1% to 2.5%; additional 0.5% to 1% with oxygen alone.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Adult

There are no dosage adjustments provided in the manufacturer’s labeling.

Dosing: Liver Impairment: Adult

There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.

Dosing: Older Adult

Refer to adult dosing. Minimum alveolar concentration is decreased in older patients.

Dosing: Pediatric
Anesthesia

Anesthesia: Inhalation: Refer to adult dosing.

Dosing: Kidney Impairment: Pediatric

There are no dosage adjustments provided in the manufacturer’s labeling.

Dosing: Liver Impairment: Pediatric

There are no dosage adjustments provided in the manufacturer’s labeling.

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Adverse reactions reported in adult and pediatric patients.

>10%:

Gastrointestinal: Nausea (recovery: 15%)

Nervous system: Agitation (induction: 52%), chills (≤14%), shivering (≤14%)

Respiratory: Breath-holding (induction: 24%; maintenance: 1%), cough (induction: 28%; maintenance: 4%)

1% to 10%:

Cardiovascular: Atrial arrhythmia (intraoperative: 2%), atrioventricular nodal arrhythmia (intraoperative: 2% to 4%), cardiac arrhythmia (postoperative: 1%), ventricular arrhythmia (intraoperative: 2% to 3%)

Gastrointestinal: Retching (induction, maintenance: ≤1%), vomiting (recovery: 10%; induction: <1%)

Nervous system: Delirium (6%), involuntary muscle movements (maintenance: 2%)

Neuromuscular & skeletal: Laryngospasm (induction: 8%; maintenance: <1%)

<1%:

Cardiovascular: Hypertension (intraoperative, postoperative), hypotension (intraoperative, postoperative)

Dermatologic: Diaphoresis (induction)

Nervous system: Abnormal electroencephalogram (convulsive pattern), mood changes, nightmares, seizure

Respiratory: Change in bronchial secretions (induction)

Frequency not defined:

Endocrine & metabolic: Decreased serum cholesterol, increased lactate dehydrogenase, increased serum glucose

Hematologic & oncologic: Leukocytosis

Hepatic: Abnormal hepatic function tests (bromsulphthalein clearance decreased), decreased serum alkaline phosphatase, increased serum alanine aminotransferase, increased serum alkaline phosphatase, increased serum aspartate aminotransferase, increased serum bilirubin

Nervous system: Asthenia, ataxia, cognitive dysfunction, confusion, dizziness, drowsiness, fatigue, nervousness

Neuromuscular & skeletal: Myalgia

Renal: Decreased blood urea nitrogen, increased serum creatinine

Postmarketing:

Cardiovascular: Acute myocardial infarction, atrial fibrillation, bradycardia, complete atrioventricular block, first-degree atrioventricular block, flushing, ischemic heart disease, low cardiac output, premature ventricular contractions, prolonged QT interval on ECG, second-degree atrioventricular block, tachycardia, torsades de pointes, ventricular fibrillation, ventricular tachycardia

Dermatologic: Skin rash

Endocrine & metabolic: Hyperkalemia (with underlying myopathies)

Gastrointestinal: Hiccups, pancreatitis

Genitourinary: Oliguria

Hematologic & oncologic: Increased hemoglobin (carboxyhemoglobin)

Hepatic: Cholestatic hepatitis, fulminant hepatitis, hepatic failure, hepatic necrosis, hepatitis, hepatotoxicity (idiosyncratic; Chalasani 2021), increased gamma-glutamyl transferase, jaundice, liver steatosis

Hypersensitivity: Hypersensitivity reaction (including anaphylaxis)

Nervous system: Awareness under anesthesia without pain, brain edema, headache, hypothermia, increased intracranial pressure, migraine, myoclonus, withdrawal syndrome (following multi-day exposure)

Neuromuscular & skeletal: Rhabdomyolysis

Ophthalmic: Anisocoria, nystagmus disorder

Renal: Acute kidney injury

Respiratory: Airway obstruction, apnea, bronchospasm, hypercapnia, hypoxia, respiratory depression, stridor

Miscellaneous: Malignant hyperthermia

Contraindications

Known sensitivity to isoflurane, other halogenated agents, or any component of the formulation; patients in whom general anesthesia is contraindicated; known or suspected genetic susceptibility to malignant hyperthermia; history of hepatitis due to a halogenated inhalational anesthetic or a history of unexplained moderate to severe liver dysfunction (eg, jaundice associated with fever and/or eosinophilia) after anesthesia with isoflurane or other halogenated inhalational anesthetics.

Warnings/Precautions

Concerns related to adverse effects:

• Cardiovascular effects: Decrease in BP is dose dependent due to peripheral vasodilation; cardiac output is maintained. Use caution in patients who are hypovolemic, hypotensive, or hemodynamically compromised; use caution in patients with coronary artery disease to avoid risk of myocardial ischemia. May prolong the QT interval and rarely torsades de pointes; use caution in patients at risk of QT prolongation. May produce cardiac steal (due to coronary vasodilation) and reflex tachycardia, but does not depress cardiac conduction nor does it sensitize the myocardium to catecholamine-induced arrhythmias like halothane (not available in the United States) (Golembiewski 2004).

• CNS depression: Advise patients to wait at least 24 hours after administration before engaging in activities which require mental alertness (operating machinery or driving).

• Decreased blood flow: May cause decrease in hepatic, renal, and splenic blood flow (Gelman 1984).

• Hepatic effects: Postoperative mild to severe hepatic dysfunction (including fatal hepatic necrosis and hepatic failure) and hepatitis with or without jaundice have been reported; may cause sensitivity hepatitis in patients who have been sensitized by previous exposure to halogenated anesthetics. Risk may be increased with repeated isoflurane exposure in a short time.

• Hyperkalemia: Use of inhaled anesthetics has been associated with rare cases of perioperative hyperkalemia that have resulted in cardiac arrhythmias (including fatalities) in pediatric patients; concomitant use of succinylcholine was associated with many of the reported cases, but not all. Risk of hyperkalemia is increased in pediatric patients with underlying neuromuscular disease (eg, Duchenne muscular dystrophy). Other abnormalities may include elevation in creatinine kinase (CK) and myoglobinuria. Aggressively identify and treat the hyperkalemia and resistant arrhythmias.

• Hypersensitivity: Hypersensitivity reactions (eg, anaphylaxis, cardiovascular collapse, difficulty breathing, hypotension, rash) have been reported.

• Increased intracranial pressure: Dilates the cerebral vasculature and may, in certain conditions, increase intracranial pressure (ICP). Administer in conjunction with ICP-reducing strategies, as clinically needed.

• Malignant hyperthermia: May trigger malignant hyperthermia; some reported cases have been fatal. Risk may be increased with concomitant administration of succinylcholine and volatile anesthetic agents and patients with genetic factors or family history of malignant hyperthermia, including ryanodine receptor or dihydropyridine receptor inherited variants. Signs of malignant hyperthermia may include arrhythmias, cyanosis, hemodynamic instability, hypercapnia, hyperthermia, hypovolemia, hypoxia, muscle rigidity, tachycardia, and tachypnea; coagulopathies, renal failure, and skin mottling may also occur. If malignant hyperthermia is suspected, discontinue triggering agents and institute appropriate therapy (eg, dantrolene) and other supportive measures.

• Obstetrical anesthesia: Increased blood loss comparable with that seen with halothane has been reported during abortions.

• Respiratory depression: Causes dose-dependent respiratory depression and blunted ventilatory response to hypoxia and hypercapnia (Golembiewski 2004).

Disease-related concerns:

• Heart failure: In a scientific statement from the American Heart Association, isoflurane has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: major) (AHA [Page 2016]).

• Hepatic impairment: Use with caution in patients with history of hepatic impairment or taking medications known to cause hepatic impairment; evaluate need for repeated exposure in a short time as clinically indicated.

Special populations:

• Pediatric neurotoxicity: In pediatric and neonatal patients <3 years and patients in third trimester of pregnancy (ie, times of rapid brain growth and synaptogenesis), the repeated or lengthy exposure to sedatives or anesthetics during surgery/procedures may have detrimental effects on child or fetal brain development and may contribute to various cognitive and behavioral problems. Epidemiological studies in humans have reported various cognitive and behavioral problems including neurodevelopmental delay (and related diagnoses), learning disabilities, and ADHD. Human clinical data suggest that single, relatively short exposures are not likely to have similar negative effects. No specific anesthetic/sedative has been found to be safer. For elective procedures, risk vs benefits should be evaluated and discussed with parents/caregivers/patients; critical surgeries should not be delayed.

Special handling:

• Occupational caution: There is no specific work exposure limit established for isoflurane. However, the National Institute for Occupational Safety and Health (NIOSH) recommends no worker be exposed to >2 ppm (ceiling concentrations) over a period of 1 hour. Precautions (eg, adequate ventilation, scavenging-systems, minimizing leaks/spills) can help to lessen any potential risk.

Other warnings/precautions:

• Desiccated absorbents: Reaction of isoflurane with desiccated CO2 absorbents produce carbon monoxide, which may result in elevated carboxyhemoglobin levels in some patients. Replace any desiccated CO2 absorbents prior to administration; the color indicator of most CO2 absorbents may not change when it becomes desiccated and, therefore, replacement of CO2 absorbents routinely regardless of color change is recommended.

• Monitoring: Transient elevations in burst suppression pattern retention, blood glucose, and SCr with decreases in alkaline phosphatase, BUN, and serum cholesterol may occur.

Dosage Forms: US

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution, Inhalation:

Forane: USP: >= 99.9 mL/100 mL (100 mL, 250 mL)

Terrell: USP: >= 99.9 mL/100 mL (100 mL, 250 mL)

Generic: USP: >= 99.9 mL/100 mL (100 mL, 250 mL)

Generic Equivalent Available: US

Yes

Administration: Adult

Via isoflurane-specific calibrated vaporizer or vaporizer with calculated flow required

Administration: Pediatric

Inhalation: Administer via isoflurane-specific calibrated vaporizer or vaporizer with calculated flow required

Use: Labeled Indications

Anesthesia: For induction and maintenance of general anesthesia. Adequate data have not been developed to establish its application in obstetrical anesthesia.

Medication Safety Issues
Sound-alike/look-alike issues:

Isoflurane may be confused with enflurane

High alert medication:

The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drug classes (anesthetic agent, general, inhaled and IV) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Acute Care Settings).

Metabolism/Transport Effects

Substrate of CYP2E1 (Minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential;

Drug Interactions

Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.

Acrivastine: May increase adverse/toxic effects of Inhalational Anesthetics. Risk C: Monitor

Alfuzosin: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Amifostine: Blood Pressure Lowering Agents may increase hypotensive effects of Amifostine. Management: When used at chemotherapy doses, hold blood pressure lowering medications for 24 hours before amifostine administration. If blood pressure lowering therapy cannot be held, do not administer amifostine. Use caution with radiotherapy doses of amifostine. Risk D: Consider Therapy Modification

Amisulpride (Oral): May increase hypotensive effects of Hypotension-Associated Agents. Risk C: Monitor

Amisulpride (Oral): May increase QTc-prolonging effects of QT-prolonging Agents (Moderate Risk). Risk C: Monitor

Amphetamines: May increase hypotensive effects of Inhalational Anesthetics. Risk C: Monitor

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may increase hypotensive effects of Antipsychotic Agents (Second Generation [Atypical]). Risk C: Monitor

Arginine: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Bambuterol: May increase arrhythmogenic effects of Inhalational Anesthetics. Management: Some labels recommend specifically avoiding halothane; others recommend separating administration by at least 6 hours; other bambuterol labels do not mention this possible interaction. Monitor for increased sensitivity to arrhythmias if coadministered. Risk D: Consider Therapy Modification

Barbiturates: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Benperidol: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Blood Pressure Lowering Agents: May increase hypotensive effects of Hypotension-Associated Agents. Risk C: Monitor

Brimonidine (Topical): May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Bromperidol: May decrease hypotensive effects of Blood Pressure Lowering Agents. Blood Pressure Lowering Agents may increase hypotensive effects of Bromperidol. Risk X: Avoid

Calcium Channel Blockers: Inhalational Anesthetics may increase hypotensive effects of Calcium Channel Blockers. Risk C: Monitor

Dabrafenib: QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of Dabrafenib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

Dexmethylphenidate-Methylphenidate: May increase hypertensive effects of Inhalational Anesthetics. Management: Avoid the use of dexmethylphenidate/methylphenidate on the day of a planned surgery with an inhalational anesthetic. Risk D: Consider Therapy Modification

Diazoxide: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Domperidone: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Domperidone. Risk X: Avoid

DOPamine: Inhalational Anesthetics may increase arrhythmogenic effects of DOPamine. Risk C: Monitor

DroPERidol: May increase CNS depressant effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). DroPERidol may increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Consider dose reductions and monitor for QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk D: Consider Therapy Modification

DULoxetine: Blood Pressure Lowering Agents may increase hypotensive effects of DULoxetine. Risk C: Monitor

Ephedra: May increase arrhythmogenic effects of Inhalational Anesthetics. Risk X: Avoid

EPHEDrine (Nasal): May increase arrhythmogenic effects of Inhalational Anesthetics. Risk X: Avoid

EPINEPHrine (Nasal): Inhalational Anesthetics may increase arrhythmogenic effects of EPINEPHrine (Nasal). Risk C: Monitor

EPINEPHrine (Oral Inhalation): Inhalational Anesthetics may increase arrhythmogenic effects of EPINEPHrine (Oral Inhalation). Risk C: Monitor

EPINEPHrine (Systemic): Inhalational Anesthetics may increase arrhythmogenic effects of EPINEPHrine (Systemic). Management: Administer epinephrine with added caution in patients receiving, or who have recently received, inhalational anesthetics. Use lower than normal doses of epinephrine and monitor for the development of cardiac arrhythmias. Risk D: Consider Therapy Modification

Esketamine (Injection): May increase sedative effects of Inhalational Anesthetics. Risk C: Monitor

Fenfluramine: May increase hypotensive effects of Inhalational Anesthetics. Risk C: Monitor

Fenoterol: Inhalational Anesthetics may increase arrhythmogenic effects of Fenoterol. Risk C: Monitor

Fluorouracil Products: QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of Fluorouracil Products. Management: Monitor for QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

Haloperidol: May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

Herbal Products with Blood Pressure Lowering Effects: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Hypotension-Associated Agents: Blood Pressure Lowering Agents may increase hypotensive effects of Hypotension-Associated Agents. Risk C: Monitor

Iloperidone: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Isocarboxazid: May increase hypotensive effects of Inhalational Anesthetics. Risk X: Avoid

Isoproterenol: Inhalational Anesthetics may increase arrhythmogenic effects of Isoproterenol. Risk X: Avoid

Levodopa-Foslevodopa: Blood Pressure Lowering Agents may increase hypotensive effects of Levodopa-Foslevodopa. Risk C: Monitor

Levoketoconazole: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Levoketoconazole. Risk X: Avoid

Lormetazepam: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Metaraminol: Inhalational Anesthetics may increase arrhythmogenic effects of Metaraminol. Risk X: Avoid

Metergoline: May decrease antihypertensive effects of Blood Pressure Lowering Agents. Blood Pressure Lowering Agents may increase orthostatic hypotensive effects of Metergoline. Risk C: Monitor

Methadone: May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase CNS depressant effects of Methadone. Management: Consider alternatives to this drug combination. If combined, monitor for QTc interval prolongation, ventricular arrhythmias, sedation, and respiratory depression. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk D: Consider Therapy Modification

Molsidomine: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Naftopidil: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Neuromuscular-Blocking Agents (Nondepolarizing): Inhalational Anesthetics may increase neuromuscular-blocking effects of Neuromuscular-Blocking Agents (Nondepolarizing). Management: When initiating a non-depolarizing neuromuscular blocking agent (NMBA) in a patient receiving an inhalational anesthetic, initial NMBA doses should be reduced 15% to 25% and doses of continuous infusions should be reduced 30% to 60%. Risk D: Consider Therapy Modification

Neuromuscular-Blocking Agents: Isoflurane may increase neuromuscular-blocking effects of Neuromuscular-Blocking Agents. Risk C: Monitor

Nicergoline: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Nicorandil: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Nitroprusside: Blood Pressure Lowering Agents may increase hypotensive effects of Nitroprusside. Risk C: Monitor

Nitrous Oxide: May increase therapeutic effects of Isoflurane. Specifically, isoflurane MAC values may be decreased. Isoflurane may increase CNS depressant effects of Nitrous Oxide. Risk C: Monitor

Norepinephrine: Inhalational Anesthetics may increase arrhythmogenic effects of Norepinephrine. Risk C: Monitor

Obinutuzumab: May increase hypotensive effects of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Risk D: Consider Therapy Modification

Ondansetron: May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

Pentamidine (Systemic): May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

Pentoxifylline: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Phenylephrine (Ophthalmic): May increase adverse/toxic effects of Inhalational Anesthetics. Specifically, the cardiovascular depressant effects of inhalational anesthetics may be increased. Risk C: Monitor

Pholcodine: Blood Pressure Lowering Agents may increase hypotensive effects of Pholcodine. Risk C: Monitor

Phosphodiesterase 5 Inhibitors: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Pimozide: May increase QTc-prolonging effects of QT-prolonging Agents (Moderate Risk). Risk X: Avoid

Piperaquine: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Piperaquine. Risk X: Avoid

Prostacyclin Analogues: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

QT-prolonging Agents (Highest Risk): QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Agents (Highest Risk). Management: Consider alternatives to this drug combination. If combined, monitor for QTc interval prolongation and ventricular arrhythmias. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk D: Consider Therapy Modification

QT-prolonging Antidepressants (Moderate Risk): QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Antidepressants (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Antipsychotics (Moderate Risk): QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Antipsychotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Class IC Antiarrhythmics (Moderate Risk): QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Class IC Antiarrhythmics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-Prolonging Inhalational Anesthetics (Moderate Risk): May increase hypotensive effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for hypotension and QTc interval prolongation and ventricular arrhythmias, including torsades de pointes when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Kinase Inhibitors (Moderate Risk): May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Miscellaneous Agents (Moderate Risk): May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk): QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Quinolone Antibiotics (Moderate Risk): QT-Prolonging Inhalational Anesthetics (Moderate Risk) may increase QTc-prolonging effects of QT-prolonging Quinolone Antibiotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk): May increase QTc-prolonging effects of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor

Quinagolide: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Reproterol: Inhalational Anesthetics may increase arrhythmogenic effects of Reproterol. Risk C: Monitor

Ritodrine: May increase adverse/toxic effects of Inhalational Anesthetics. Risk C: Monitor

Sertindole: May increase QTc-prolonging effects of QT-prolonging Agents (Moderate Risk). Risk X: Avoid

Silodosin: May increase hypotensive effects of Blood Pressure Lowering Agents. Risk C: Monitor

Thioridazine: QT-prolonging Agents (Moderate Risk) may increase QTc-prolonging effects of Thioridazine. Risk X: Avoid

Pregnancy Considerations

Isoflurane crosses the placenta (Dwyer 1995; Satoh 1995).

Based on animal data, repeated or prolonged use of general anesthetic and sedation medications that block N-methyl-D- aspartate (NMDA) receptors and/or potentiate gamma-aminobutyric acid (GABA) activity, may affect brain development. Evaluate benefits and potential risks of fetal exposure to isoflurane when duration of surgery is expected to be >3 hours (Olutoye 2018).

Use of isoflurane in obstetric anesthesia has been described (Abboud 1989; ACOG 209 2019; Devroe 2015; Ghaly 1988; Liu 2013). Maternal exposure should be minimized due to dose dependent uterine relaxation and fetal depression (ACOG 209 2019; Devroe 2015).

The ACOG recommends that pregnant patients should not be denied medically necessary surgery, regardless of trimester. If the procedure is elective, it should be delayed until after delivery (ACOG 775 2019).

Breastfeeding Considerations

It is not known if isoflurane is present in breast milk.

According to the manufacturer, the decision to breastfeed should consider the risk of infant exposure and the benefits of breastfeeding to the infant. Based on pharmacokinetic properties, use of isoflurane in breastfeeding patients may be considered acceptable (Lee 1993). The Academy of Breastfeeding Medicine recommends postponing elective surgery until milk supply and breastfeeding are established. Milk should be expressed ahead of surgery when possible. In general, when the child is healthy and full term, breastfeeding may resume, or milk may be expressed once the mother is awake and in recovery. For children who are at risk for apnea, hypotension, or hypotonia, milk may be saved for later use when the child is at lower risk (ABM [Reece-Stremtan 2017]).

Monitoring Parameters

Burst suppression pattern, BP, electrocardiogram, serum potassium, SCr, BUN, oxygen saturation, respiration, end-tidal CO2 and isoflurane concentrations should be monitored prior to and throughout anesthesia; consider additional cardiac monitoring in patients with coronary artery disease; QT interval in patients at risk for QTc prolongation; blood glucose; alkaline phosphatase; serum cholesterol.

Mechanism of Action

Isoflurane is a general anesthetic agent capable of producing profound respiratory depression. Inhaled anesthetics alter activity of neuronal ion channels, particularly the fast synaptic neurotransmitter receptors (nicotinic acetylcholine, gamma-aminobutyric acid [GABA], and glutamate receptors). May depress myocardial contractility, decrease blood pressure through a decrease in systemic vascular resistance, and decrease sympathetic nervous activity (Stachnik 2006).

Pharmacokinetics (Adult Data Unless Noted)

Metabolism: Minimally hepatic (<0.2%), predominantly CYP2E1 (Golembiewski 2004)

Excretion: Exhaled gases

Brand Names: International
International Brand Names by Country
For country code abbreviations (show table)

  • (AE) United Arab Emirates: Aerrane | Forane;
  • (AR) Argentina: Forane | Isoflurano | Zuflax;
  • (AT) Austria: Forane | Isofluran | Isofluran Rhodia;
  • (AU) Australia: Aerrane | Forthane;
  • (BD) Bangladesh: Forane;
  • (BE) Belgium: Aerrane | Forene;
  • (BG) Bulgaria: Forane | Terrell;
  • (BR) Brazil: Isoflurano | Isoforine | Isoran | Isothane;
  • (CN) China: Aerrane | Forane | Ning fen | Terrell | Yi mei ning;
  • (CO) Colombia: Isoflurano | Isorane | Terrell;
  • (CZ) Czech Republic: Aerrane | Forane | Isofluran nicholas piramal;
  • (DE) Germany: Forane | Forene | Isofluran | Isofluran DeltaSelect;
  • (DO) Dominican Republic: Isoforine;
  • (EE) Estonia: Aerrane | Forane | Isofluran baxter | Isofluran piramal;
  • (EG) Egypt: Aerrane | Anahal | Forane | Isoflurane Sedico | Mira isoflurane;
  • (ES) Spain: Aerrane | Forane | Isoflurano inibsa | Sedaconda;
  • (ET) Ethiopia: Forane;
  • (FI) Finland: Forene | Isofluran baxter | Isofluran Rhodia;
  • (FR) France: Aerrane | Cedaconda | Forane | Forene | Forene ecofil;
  • (GB) United Kingdom: Aerrane | Forane | Isoflurane abbott | Isoflurane bioglan;
  • (GR) Greece: Forenium;
  • (HK) Hong Kong: Aerrane | Forane;
  • (HU) Hungary: Aerrane | Forane;
  • (ID) Indonesia: Aerrane | Forane | Terrell;
  • (IE) Ireland: Forane;
  • (IN) India: Aerrane | Forane | Iflurane | Isifrane | Isorane | Isotroy;
  • (IT) Italy: Aerrane | Forane;
  • (JO) Jordan: Aerrane | Floran | Forane;
  • (JP) Japan: Escain | Forane | Isoflurane merck hoei;
  • (KE) Kenya: Forane | Isotroy;
  • (KR) Korea, Republic of: Aerane | Forane | I-Fran | Rhodiaisoflurane | Terrel;
  • (KW) Kuwait: Aerrane | Forane;
  • (LB) Lebanon: Forane;
  • (LT) Lithuania: Forane;
  • (LU) Luxembourg: Forene;
  • (LV) Latvia: Forane;
  • (MX) Mexico: Dorin | Fluduk | Forane | Isoflurano | Lisorane | Sofloran;
  • (MY) Malaysia: Aerrane | Forane | Isorane;
  • (NG) Nigeria: Forane | Isotroy;
  • (NL) Netherlands: Forene | Isofluraan | Sedaconda;
  • (NO) Norway: Aerrane | Forene | Isofluran | Sedaconda;
  • (NZ) New Zealand: Aerrane | Forane;
  • (PE) Peru: Isoflurano;
  • (PH) Philippines: Aerrane | Florane | Forane | Isorane | Pascual isoflurane;
  • (PK) Pakistan: Forane;
  • (PL) Poland: Aerrane | Forane;
  • (PR) Puerto Rico: Forane;
  • (PT) Portugal: Aerrane | Forene | Isoflurano;
  • (PY) Paraguay: Forane | Isoflurano interlabo | Isoflurano omicron | Isoflurano prosalud | Isoflurano quimfa | Isoflurano usp interlabo | Isoforine | Zuflax;
  • (QA) Qatar: Aerrane | Floran;
  • (RO) Romania: Aerrane | Anesteran | Forane;
  • (RU) Russian Federation: Aerrane | Forane;
  • (SA) Saudi Arabia: Aerrane | Floran | Forane;
  • (SE) Sweden: Aerrane | Forene | Isofluran baxter | Isofluran Rhodia | Isoflurane Medeva Europe | Sedaconda;
  • (SG) Singapore: Aerrane | Forane;
  • (SI) Slovenia: Forane | Isofluran;
  • (SK) Slovakia: Forane | Isofluran Rhodia;
  • (SR) Suriname: Isofluraan;
  • (TH) Thailand: Aerrane | Forane | Isofluran Rhodia | Terrell;
  • (TN) Tunisia: Forene;
  • (TR) Turkey: Aerrane | Forane | Isoflurane usp;
  • (TW) Taiwan: Aerrane | Forane;
  • (UA) Ukraine: Forane;
  • (UG) Uganda: Forane | Isotroy;
  • (UY) Uruguay: Forane | Isoflurano Zeneca | Isoforine | Terrell;
  • (VE) Venezuela, Bolivarian Republic of: Forene | Isoflurano | Isoflurano usp;
  • (ZA) South Africa: Aerrane | Forane | Isofor;
  • (ZM) Zambia: Forane | Isotroy;
  • (ZW) Zimbabwe: Forane
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