Article: Isoflurane

Systematic (IUPAC) name
CAS number 26675-46-7
ATC code N01AB06
PubChem 3763
DrugBank APRD00212
Chemical data
Formula C3H2F6O
Mol. weight 168.038 g/mol
Pharmacokinetic data
Bioavailability  ?
Metabolism  ?
Half life  ?
Excretion  ?
Therapeutic considerations
Pregnancy cat.


Legal status
Routes  ?

Isoflurane (2-chloro-2-(difluoromethoxy)-1,1,1-trifluoro-ethane) is a halogenated ether used for inhalation anesthesia. Together with enflurane and halothane, it replaced the flammable ethers used in the pioneer days of surgery. Its use in human medicine is now starting to decline, being replaced with sevoflurane, desflurane and the intravenous anaesthetic propofol. Isoflurane is still frequently used for veterinary anaesthesia.

Isoflurane is always administered in conjunction with air and/or pure oxygen. Often nitrous oxide is also used. Although its physical properties means that anaesthesia can be induced more rapidly than with halothane, its pungency can irritate the respiratory system, negating this theoretical advantages conferred by its physical properties. It is usually used to maintain a state of general anesthesia that has been induced with another drug, such as thiopentone or propofol.

A major advantage of isoflurane is that it is no longer patented, and hence very economical to use.

It vaporizes readily, but is a liquid at room temperature. It is completely non-flammable.

Physical properties

Molecular weight 184.5 g/mol
Boiling point (at 1 atm): 48.5 °C
Density (at 25 °C): 1.496 g/mL
MAC : 1.15 vol %
Vapor pressure: 238 mmHg 31.7 kPa (at 20°C)
295 mmHg 39.3 kPa (at 25°C)
367 mmHg 48.9 kPa (at 30°C)
450 mmHg 60.0 kPa (at 35°C)
Blood:Gas Partition coefficient: 1.4
Oil:Gas Partition coefficient: 98