Isoflurane, sold under the brand name Forane among others, is a general anesthetic.[3] It can be used to start or maintain anesthesia; however, other medications are often used to start anesthesia rather than isoflurane, due to airway irritation with isoflurane.[2][4] Isoflurane is given via inhalation.[3]
Isoflurane is always administered in conjunction with air or pure oxygen. Often, nitrous oxide is also used. Although its physical properties imply that anaesthesia can be induced more rapidly than with halothane,[9] its pungency can irritate the respiratory system, negating any possible advantage conferred by its physical properties. Thus, it is mostly used in general anesthesia as a maintenance agent after induction of general anesthesia with an intravenous agent such as thiopentone or propofol.[10][11][12]
Adverse effects
Isoflurane can cause a sudden decrease in blood pressure due to dose-dependent peripheral vasodilation. This may be specially marked in hypovolemic patients.[12]
Animal studies have raised safety concerns of certain general anesthetics, in particular ketamine and isoflurane, in young children. The risk of neurodegeneration was increased in combination of these agents with nitrous oxide and benzodiazepines such as midazolam.[13] Whether these concerns occur in humans is unclear.[13]
Elderly
Biophysical studies using NMR spectroscopy has provided molecular details of how inhaled anesthetics interact with three amino acid residues (G29, A30 and I31) of amyloid beta peptide and induce aggregation. This area is important as "some of the commonly used inhaled anesthetics may cause brain damage that accelerates the onset of Alzheimer's disease".[14]
It is administered as a racemic mixture of (R)- and (S)-optical isomers.[17][18] Isoflurane has a melting point of 48 - 48.5°Celsius (118 - 119°Fahrenheit) and a boiling point of 48.5 - 49 °C (119 - 120 °F).[15] It is non-combustible but can give off irritable and toxic fumes when exposed to flame.[15]
The average lifetime of isoflurane in the atmosphere is 3.2 years, its global warming potential is 510 and the yearly emissions add up to 880 tons.[31]
^World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
^World Health Organization (2021). World Health Organization model list of essential medicines: 22nd list (2021). Geneva: World Health Organization. hdl:10665/345533. WHO/MHP/HPS/EML/2021.02.
^Pauca AL, Dripps RD (July 1973). "Clinical experience with isoflurane (Forane): preliminary communication". British Journal of Anaesthesia. 45 (7): 697–703. doi:10.1093/bja/45.7.697. PMID4730162.
^Chen Z (August 2004). "The effects of isoflurane and propofol on intraoperative neurophysiological monitoring during spinal surgery". Journal of Clinical Monitoring and Computing. 18 (4): 303–308. doi:10.1007/s10877-005-5097-5. PMID15779842. S2CID195331061.
^ abcdef"Isoflurane". PubChem. U.S. National Library of Medicine. Retrieved 2022-04-07.
^Seto T, Mashimo T, Yoshiya I, Kanashiro M, Taniguchi Y (January 1992). "The solubility of volatile anaesthetics in water at 25.0 degrees C using 19F NMR spectroscopy". Journal of Pharmaceutical and Biomedical Analysis. 10 (1): 1–7. doi:10.1016/0731-7085(92)80003-6. PMID1391078.
^Jenkins A, Franks NP, Lieb WR (February 1999). "Effects of temperature and volatile anesthetics on GABA(A) receptors". Anesthesiology. 90 (2): 484–491. doi:10.1097/00000542-199902000-00024. PMID9952156.
^Lin LH, Chen LL, Zirrolli JA, Harris RA (November 1992). "General anesthetics potentiate gamma-aminobutyric acid actions on gamma-aminobutyric acidA receptors expressed by Xenopus oocytes: lack of involvement of intracellular calcium". The Journal of Pharmacology and Experimental Therapeutics. 263 (2): 569–578. PMID1331405.
^Terrell RC (March 2008). "The invention and development of enflurane, isoflurane, sevoflurane, and desflurane". Anesthesiology. 108 (3): 531–533. doi:10.1097/ALN.0b013e31816499cc. PMID18292690.
^Ludders JW (March 1992). "Advantages and guidelines for using isoflurane". The Veterinary Clinics of North America. Small Animal Practice. 22 (2): 328–331. doi:10.1016/s0195-5616(92)50626-x. PMID1585568.