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Isoflurane

General Description

  • Synonyms: 1-Chloro-2,2,2-Trifluoroethyl Difluoromethyl Ether; 2-Chloro-2-(Difluoromethoxy)-1,1,1-trifluoro Ethane; Forane
  • OSHA IMIS Code Number: F118
  • Chemical Abstracts Service (CAS) Registry Number: 26675-46-7
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: KN6799000
  • Chemical Description and Physical Properties:
    • colorless liquid
    • molecular weight: 184.50
    • vapor pressure: 32 kPa @ 20°C
    • molecular formula: C3H2ClF5O
    • boiling point: 48.5°C

Health Factors

  • Carcinogenic Classification:
  • Potential Symptoms: Irritation of eyes, skin, respiratory tract; cough, sore throat; headache, drowsiness, dizziness; asphyxia; unconsciousness
  • Health Effects: Narcosis (HE8); Asphyxiant (HE17)
  • Affected Organs: CNS
  • Notes:
    1. OSHA does not have a PEL for isoflurane.
    2. Isoflurane is used as a general anesthetic by inhalation. Its minimum alveolar concentration (MAC, a special type of ED50) is approximately 1.15%. Significant subjective effects and significant deficits in psychomotor tests occurred in volunteers (n=14) at a concentration of 0.2%.
    3. A comparison of the irritating effects (coughing, burning sensation, tolerability) of isoflurane, desflurane, and sevoflurane (n=27 male patients per anesthetic) at concentrations of 2 MAC for a one-minute exposure indicated that 2.3% isoflurane is more irritating than 4% sevoflurane and less irritating than 12% desflurane.
    4. Studies with patients undergoing anesthesia indicated that a small amount of isoflurane (approximately 0.2% of what is systemically absorbed) is metabolized to trifluoroacetic acid and inorganic fluoride by cytochrome P450 2E1 and that this metabolism is inhibited by disulfiram.
    5. Tissue levels of isoflurane have been measured in two fatal cases involving isoflurane abuse.
    6. Measurement of urinary isoflurane has been suggested as a suitable means for biomonitoring exposure in operating room personnel.
  • Literature Basis:
    • International Chemical Safety Cards (WHO/IPCS/ILO): Isoflurane.
    • Accorsi, A., Barbieri, A., Raffi, G.B. and Violante, F.S.: Biomonitoring of exposure to nitrous oxide, sevoflurane, isoflurane and halothane by automated GC/MS headspace urinalysis. Int. Arch. Occup. Environ. Health 74(8): 541-548, 2001.
    • Beckman, N.J., Zacny, J.P. and Walker, D.J.: Within-subject comparison of the subjective and psychomotor effects of a gaseous anesthetic and two volatile anesthetics in health volunteers. Drug Alcohol Depend. 81(1): 89-95, 2006.
    • Kharasch, E.D., Hankins, D.C. and Cox, K.: Clinical isoflurane metabolism by cytochrome P450 2E1. Anesthesiology 90(3): 766-771, 1999.
    • Kuhlman, J.J., Jr., Magluilo, J., Jr., Levine, B. and Smith, M.L.: Two deaths involving isoflurane abuse. J. Forensic Sci. 38(4): 968-971, 1993.
    • Stachnik, J.: Inhaled anesthetic agents. Am. J. Health Syst. Pharm. 63(7): 623-634, 2006.
    • TerRiet, M.F., et al.: Which is most pungent: isoflurane, sevoflurane or desflurane? Br. J. Anaesth. 85(2): 305-307, 2000.
  • Date Last Revised: 06/13/2006

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Anasorb 747 Tube (140/70 mg sections)
  • maximum volume: 12 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • analytical solvent: Carbon Disulfide
  • method reference: OSHA Analytical Method (OSHA 103)
  • method classification: Fully Validated
  • Anasorb CMS Tube (150/75 mg sections)
  • maximum volume: 12 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • analytical solvent: Carbon Disulfide
  • method reference: OSHA Analytical Method (OSHA 103)
  • method classification: Fully Validated

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