Isoflurane

Mechanism-of-action classes: GABA A Modulators; Glycine Agonists.

• Isoflurane USP may be used for induction and maintenance of general anesthesia. Adequate data have not been developed to establish its application in obstetrical anesthesia.

• Isoflurane USP is contraindicated in patients: • in whom general anesthesia is contraindicated. • with known sensitivity to Isoflurane USP or to other halogenated agents [see Warnings and Precautions ( 5.3 )].contraindicated

• Isoflurane USP should be administered only by persons trained in the administration of general anesthesia. Isoflurane USP should only be delivered using a vaporizer specifically designed and designated for use with isoflurane. ( 2 ) • The administration of general anesthesia must be individualized and titrated based on the patient’s age and clinical status. ( 2 ) 2.1 Important Dosage and Administration Information Isoflurane should be administered only by persons trained in the administration of general anesthesia. Facilities for maintenance of a patent airway, artificial ventilation, oxygen enrichment, and circulatory resuscitation must be immediately available. Isoflurane is administered by inhalation. Isoflurane should be delivered from a vaporizer specifically designed for use with isoflurane. Dosage for induction and maintenance must be individualized and titrated to the desired effect according to the patient’s age and clinical status. With the exception of neonates, the minimum alveolar concentration (MAC) of isoflurane decreases with increasing patient age. Nitrous oxide decreases the MAC of isoflurane (see Table 1 ). Opioids decrease the MAC of isoflurane [see Drug Interactions (7) ]. Isoflurane potentiates the muscle relaxant effect of all neuromuscular blockers and decreases the required doses of neuromuscular blocking agents [see Drug Interactions (7) ] . The dose should be adjusted accordingly.

• Malignant Hyperthermia : Malignant hyperthermia may occur, especially in individuals with known or suspected susceptibility based on genetic factors or family history. Discontinue triggering agents, administer intravenous dantrolene sodium, and apply supportive therapies. ( 5.1 ) • Perioperative Hyperkalemia : Perioperative hyperkalemia may occur. Patients with latent or overt neuromuscular disease, particularly with Duchenne muscular dystrophy, appear to be most vulnerable. Early, aggressive intervention is recommended. ( 5.2 ) • Hepatic Reactions : May cause sensitivity hepatitis in patients sensitized by previous exposure to halogenated anesthetics. Approach repeated anesthesia with caution. ( 5.3 ) • Hypersensitivity Reactions : Allergic-type hypersensitivity reactions, including anaphylaxis, have been reported with isoflurane. ( 5.4 ) • Abortions : Increased blood loss comparable to that seen with halothane has been observed in patients undergoing abortions. ( 5.5 ) • QT Prolongation : Carefully monitor cardiac rhythm when administering Isoflurane USP to susceptible patients. ( 5.6 ) • Interactions with Desiccated Carbon Dioxide (CO 2 ) Absorbents: May react with desiccated CO 2 absorbents to produce carbon monoxide. Replace desiccated CO 2 absorbent before administration of Isoflurane USP. ( 5.7 ) • Pediatric Neurotoxicity : In developing animals, exposures greater than 3 hours cause neurotoxicity. Weigh benefits against potential risks when considering elective procedures in children under 3 years old.

Most common adverse reactions (incidence > 5%) are agitation, cough, breath holding, nausea, chills/shivering, vomiting, laryngospasm, delirium. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Piramal Critical Care, Inc. at 1-888-822-8431 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience The following adverse reactions were identified from controlled clinical trials of adult and pediatric subjects exposed to Isoflurane USP. The trials were conducted using a variety of pre-medications, other anesthetics, and surgical procedures of varying lengths. The most serious reported adverse reactions in alphabetical order are agitation, arrhythmia, breath holding, elevated liver enzyme, hypotension and laryngospasm. The most frequent adverse reactions (incidence ³ 5%) described in Table 1 are agitation, breath holding, chills/shivering, cough, delirium, laryngospasm, nausea, and vomiting. Adverse reactions with an incidence between 1% and 5% are provided in Table 2. Adverse reactions with an incidence less than 1% are provided in Table 3. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

. Geriatric Use : The minimum alveolar concentration (MAC) of Isoflurane USP decreases with increasing patient age. ( 8.5 ) See 17 for PATIENT COUNSELING INFORMATION. Revised: 11/2025 8.1 Pregnancy Risk Summary There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, embryofetal toxicity was noted in pregnant mice exposed to 0.075% (increased post implantation losses) and 0.3% isoflurane (increased post implantation losses and decreased livebirth index) during organogenesis. Published studies in pregnant primates demonstrate that the administration of anesthetic and sedation drugs that block NMDA receptors and/or potentiate GABA activity during the period of peak brain development increases neuronal apoptosis in the developing brain of the offspring when used for longer than 3 hours. There are no data on pregnancy exposures in primates corresponding to periods prior to the third trimester in humans (see Data). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15- 20%, respectively.

Metabolism

Isoflurane undergoes minimal biotransformation in man. In the postanesthesia period, only 0.17% of the isoflurane taken up can be recovered as urinary metabolites.

The symptoms of overdosage of Isoflurane USP can present as a deepening of anesthesia, cardiac and/or respiratory depression in spontaneously breathing patients, and cardiac depression in ventilated patients in whom hypercapnia and hypoxia may occur only at a late stage. In the event of overdosage, or what may appear to be overdosage, the following action should be taken, as appropriate: Stop drug administration, establish a clear airway, and initiate assisted or controlled ventilation with pure oxygen. Monitor cardiovascular function and manage signs of poor end-organ perfusion as clinically indicated.

• Dec 18, 1979NDANDA017624Baxter Hlthcare
• Sep 30, 1994ANDAANDA074416Piramal Critical
• Jun 27, 1995ANDAANDA074502Piramal Pharma
• Oct 20, 1999ANDAANDA075225Halocarbon Prods
• Nov 4, 2025ANDAANDA216527Shandong

1. 1Hypotension23512%
2. 2Drug Ineffective1759.2%
3. 3Renal Failure1588.3%
4. 4Pain1497.8%
5. 5Injury1367.1%
6. 6Anxiety1286.7%
7. 7Unevaluable Event1236.4%
8. 8Drug Interaction1216.3%
9. 9Off Label Use1146.0%
10. 10Fear1105.8%
11. 11Emotional Distress1035.4%
12. 12Hyperthermia Malignant1035.4%
13. 13Renal Injury995.2%
14. 14Death985.1%
15. 15Renal Impairment944.9%

Recent PubMed references pinned to Isoflurane as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Brief Communication: Increased Frequency of Micronucleus in the Bone Marrow of Mice Under Simulated Occupational Exposure to Isoflurane.
  Environmental and molecular mutagenesis · 2026 · Zanin M, Braz MG, Destro MV, et al.
  PMID 42112785DOI 10.1002/em.70052
• Early Isoflurane Exposure Is Associated With Delayed Adolescent Neurobehavioral Deficits, Accompanied by Dysregulation of FOXG1 and EB3.
  Developmental neurobiology · 2026 · Chen K, Xia M, Li C, et al.
  PMID 42063249DOI 10.1002/dneu.70033
• Chloral Hydrate versus Isofluorane anesthesia and their differential impact on the midbrain system.
  Journal of neuroscience methods · 2026 · Hamza A, Grace AA
  PMID 42002006DOI 10.1016/j.jneumeth.2026.110778
• MiR-372-3p alleviates isoflurane-induced cognitive dysfunction by targeting STAT3 to mitigate neuroinflammation and oxidative stress.
  Neuroscience letters · 2026 · Zhao M, Li T, Zhang Q, et al.
  PMID 41980675DOI 10.1016/j.neulet.2026.138606
• Impact of low-flow desflurane versus sevoflurane anesthesia on thiol-disulfide homeostasis in adults undergoing elective thyroidectomy: a randomized controlled trial.
  Revista da Associacao Medica Brasileira (1992) · 2026 · Sen E, Aytekin A
  PMID 41919881DOI 10.1590/1806-9282.20250893
• Intranasal rosmarinic acid reduces cognitive and hippocampal damage from repeated neonatal isoflurane exposure by regulating apoptotic/oxidative/inflammatory responses, and heat-shock and 14-3-3 proteins.
  Neurotoxicology · 2026 · Demirgan S, Şengelen A, Aksüt Y, et al.
  PMID 41905503DOI 10.1016/j.neuro.2026.103440
• Utility of dynamic preload indices of hypovolemia in isoflurane-anesthetized horses.
  Veterinary anaesthesia and analgesia · 2026 · Byrne J, Guedes AG, Hickey C, et al.
  PMID 41825215DOI 10.1016/j.vaa.2026.101205
• Choosing wisely: Effects of propofol and alfaxalone induction on maternal and neonatal outcomes in isoflurane-anesthetized dogs undergoing cesarean section.
  Veterinary journal (London, England : 1997) · 2026 · Antończyk A, Ligocka-Kowalczyk Z, Ochota M, et al.
  PMID 41759766DOI 10.1016/j.tvjl.2026.106618

The 10 most recently updated of 199 ClinicalTrials.gov registrations naming Isoflurane as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Volatile Sedation for Patients With the Acute Respiratory Distress Syndrome
  Recruiting · Phase 2 · Phase 3 · Interventional · 20 enrolled · Guy's and St Thomas' NHS Foundation Trust
  NCT06014138updated 2026-06-04
• Inhaled Sedation in Critically Ill Patients
  Recruiting · Phase 4 · Interventional · 620 enrolled · Instituto de Investigación Hospital Universitario La Paz
  NCT07000526updated 2026-05-19
• Dexmedetomidine Versus Nitroglycerin on Surgical Field Quality and Drug Cost in Functional Endoscopic Sinus Surgeries
  Completed · Interventional · 66 enrolled · Zagazig University
  NCT07585201updated 2026-05-13
• Inhalational Sedation and Mechanical Power
  Completed · Interventional · 40 enrolled · Mahidol University
  NCT05559970updated 2026-05-07
• GA + ESP vs. SA + ESP in Lumbar Decompression Surgeries
  Enrolling by invitation · Phase 3 · Interventional · 142 enrolled · Hospital for Special Surgery, New York
  NCT05444751updated 2026-04-28
• The Influence of Genetic Polymorphism on Dose- Dependent Analgesic Response and Safety to Propofol in General Anesthesia
  Active not recruiting · Interventional · 159 enrolled · Superior University
  NCT07543523updated 2026-04-22
• Anesthesia and Non-small Cell Lung Cancer Recurrence
  Recruiting · Phase 4 · Interventional · 5,384 enrolled · Samsung Medical Center
  NCT06330038updated 2026-04-20
• Exploring the Impact of Genetic Variations on The Clinical Efficacy of Nalbuphine in Postoperative Pain Management
  Recruiting · Phase 2 · Phase 3 · Interventional · 263 enrolled · Dr. Asma Abdus Salam
  NCT06996561updated 2026-04-15
• Ultrasound-Guided Erector Spinae Plane Block for Postoperative Pain Control in Lumbar Spondylolisthesis Surgery
  Completed · Interventional · 50 enrolled · Bangladesh Medical University
  NCT07514806updated 2026-04-09
• Continuous Versus Single-Shot Spinal Anesthesia for Orthopedic Surgery
  Completed · Interventional · 105 enrolled · Benha University
  NCT06625606updated 2026-03-31

CPIC-curated drug–gene pairs for Isoflurane. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

• CACNA1SCPIC AClinPGx 1AFDA label: Actionable PGx
  RYR1, CACNA1S and Volatile anesthetic agents and Succinylcholine
• RYR1CPIC AClinPGx 1AFDA label: Actionable PGx
  RYR1, CACNA1S and Volatile anesthetic agents and Succinylcholine

Frequently asked questions

How does Isoflurane work?

Mechanism-of-action classes: GABA A Modulators; Glycine Agonists.

What is Isoflurane used for?

According to FDA labeling, Isoflurane carries indications including: Isoflurane USP may be used for induction and maintenance of general anesthesia. Adequate data have not been developed to establish its application in obstetrical anesthesia.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Isoflurane?

Isoflurane is classified as Halogenated hydrocarbons, General Anesthetic, GABA A Modulators, Glycine Agonists, Cerebral Arterial Vasoconstriction, Decreased Medullary Respiratory Drive, Decreased Organized Electrical Activity, General Anesthesia, Vasodilation.

What are the brand names for Isoflurane?

Isoflurane is marketed under brand names including Fluriso, Forane, IsoSol, Isospire, Terrell.

What are the contraindications for Isoflurane?

Isoflurane labeling lists contraindications including: Isoflurane USP is contraindicated in patients: • in whom general anesthesia is contraindicated. • with known sensitivity to Isoflurane USP or to other halogenated agents [see Warnings and Precautions ( 5.3 )].. Always consult the full prescribing information and a clinician.