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2D Structure
Also known as: 13838-16-9, Methylflurether, 2-chloro-1-(difluoromethoxy)-1,1,2-trifluoroethane, Efrane, Ethrane, Alyrane
Molecular Formula
C3H2ClF5O
Molecular Weight
184.49  g/mol
InChI Key
JPGQOUSTVILISH-UHFFFAOYSA-N
FDA UNII
91I69L5AY5

An extremely stable inhalation anesthetic that allows rapid adjustments of anesthesia depth with little change in pulse or respiratory rate.
Enflurane is a General Anesthetic. The physiologic effect of enflurane is by means of General Anesthesia.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
2-chloro-1-(difluoromethoxy)-1,1,2-trifluoroethane
2.1.2 InChI
InChI=1S/C3H2ClF5O/c4-1(5)3(8,9)10-2(6)7/h1-2H
2.1.3 InChI Key
JPGQOUSTVILISH-UHFFFAOYSA-N
2.1.4 Canonical SMILES
C(C(OC(F)F)(F)F)(F)Cl
2.2 Other Identifiers
2.2.1 UNII
91I69L5AY5
2.3 Synonyms
2.3.1 MeSH Synonyms

1. Alyrane

2. Enfran

3. Enlirane

4. Ethrane

5. Etran

2.3.2 Depositor-Supplied Synonyms

1. 13838-16-9

2. Methylflurether

3. 2-chloro-1-(difluoromethoxy)-1,1,2-trifluoroethane

4. Efrane

5. Ethrane

6. Alyrane

7. 2-chloro-1,1,2-trifluoroethyl Difluoromethyl Ether

8. Compound 347

9. Anesthetic 347

10. Anesthetic Compound No. 347

11. Ohio 347

12. Enflurano

13. Enfluranum [inn-latin]

14. Enflurano [inn-spanish]

15. Nsc-115944

16. Ethane, 2-chloro-1-(difluoromethoxy)-1,1,2-trifluoro-

17. C 347

18. Ether, 2-chloro-1,1,2-trifluoroethyl Difluoromethyl

19. Chebi:4792

20. 91i69l5ay5

21. R-e-235ca2

22. Ncgc00167422-01

23. Enfluranum

24. Dsstox_cid_562

25. Dsstox_rid_75661

26. Dsstox_gsid_20562

27. Ethrane (tn)

28. Cas-13838-16-9

29. Einecs 237-553-4

30. Brn 1903921

31. Unii-91i69l5ay5

32. Hsdb 7909

33. Enflurane [anaesthetics, Volatile]

34. Enflurane [usan:usp:inn:ban:jan]

35. (+-)-2-chloro-1,1,2-trifluoroethyl Difluoromethyl Ether

36. Wln: Gyfxffoyff

37. Enflurane [inn]

38. Enflurane [jan]

39. Enflurane [mi]

40. Enflurane [usan]

41. Enflurane [vandf]

42. Enflurane [mart.]

43. Enflurane [usp-rs]

44. Enflurane [who-dd]

45. Chembl1257

46. Schembl61712

47. Enflurane (jp17/usp/inn)

48. Enflurane [green Book]

49. Gtpl7175

50. Enflurane [orange Book]

51. Dtxsid1020562

52. Enflurane [usp Impurity]

53. Enflurane [usp Monograph]

54. Act02934

55. Amy14276

56. Ethane, 2-chloro-1-(difluoromethoxy)-1,1,2-trifluoro-, (+-)-

57. Tox21_112426

58. Tox21_200166

59. Mfcd00069095

60. Nsc115944

61. Akos015853043

62. Db00228

63. Ether,1,2-trifluoroethyl Difluoromethyl

64. 4-chloro-1h,4h-perfluoro(2-oxabutane)

65. Ncgc00167422-02

66. Ncgc00257720-01

67. As-69470

68. Db-042426

69. Ft-0625662

70. C07516

71. D00543

72. D83877

73. 2-chloro-1,1,2-trifluoroethyldifluoromethylether

74. 2-chloro-1,2-trifluoroethyl Difluoromethyl Ether

75. 2-chloro-1-(difluoromethoxy)-1,2-trifluoroethane

76. Q416740

77. Sr-01000944966

78. 2-chloro-1,1,2-difluoroethane, 1-difluoromethoxy-

79. Sr-01000944966-1

80. 2- Chloro-1,1,2-trifluoroethyl Difluoromethyl Ether

81. 2-chloro-1-(difluoromethoxy)-1,1,2-trifluoro-ethane

82. 2-chloro-1,1,2-trifluoroethyl Difluoromethyl Ether, Aldrichcpr

83. (+/-)-2-chloro-1,1,2-trifluoroethyl Difluoromethyl Ether

84. Ethane, 2-chloro-1-(difluoromethoxy)-1,1,2-trifluoro-, (+/-)-

2.4 Create Date
2004-09-16
3 Chemical and Physical Properties
Molecular Weight 184.49 g/mol
Molecular Formula C3H2ClF5O
XLogP32.1
Hydrogen Bond Donor Count0
Hydrogen Bond Acceptor Count6
Rotatable Bond Count3
Exact Mass183.9714332 g/mol
Monoisotopic Mass183.9714332 g/mol
Topological Polar Surface Area9.2 Ų
Heavy Atom Count10
Formal Charge0
Complexity107
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count1
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Information
1 of 4  
Drug NameEnflurane
Drug LabelEnflurane, USP, a nonflammable liquid administered by vaporizing, is a general inhalation anesthetic drug. It is 2-chloro-1,1,2-trifluoroethyl difluoromethyl ether, (CHF2OCF2CHFCl). The boiling point is 56.5C at 760 mm Hg, and the vapor pressure (i...
Active IngredientEnflurane
Dosage FormLiquid
RouteInhalation
Strength99.9%
Market StatusPrescription
CompanyPiramal Critical

2 of 4  
Drug NameEthrane
Active IngredientEnflurane
Dosage FormLiquid
RouteInhalation
Strength99.9%
Market StatusPrescription
CompanyBaxter Hlthcare

3 of 4  
Drug NameEnflurane
Drug LabelEnflurane, USP, a nonflammable liquid administered by vaporizing, is a general inhalation anesthetic drug. It is 2-chloro-1,1,2-trifluoroethyl difluoromethyl ether, (CHF2OCF2CHFCl). The boiling point is 56.5C at 760 mm Hg, and the vapor pressure (i...
Active IngredientEnflurane
Dosage FormLiquid
RouteInhalation
Strength99.9%
Market StatusPrescription
CompanyPiramal Critical

4 of 4  
Drug NameEthrane
Active IngredientEnflurane
Dosage FormLiquid
RouteInhalation
Strength99.9%
Market StatusPrescription
CompanyBaxter Hlthcare

4.2 Therapeutic Uses

Anesthetics, Inhalation

National Library of Medicine; Medical Subject Headings (MeSH) (2011). Available from, as of March 10, 2011: https://www.nlm.nih.gov/mesh/2011/mesh_browser/MBrowser.html


Enflurane may be used for induction and maintenance of general anesthesia. Enflurane may be used to provide analgesia for vaginal delivery. Low concentrations of enflurane (see DOSAGE AND ADMINISTRATION) may also be used to supplement other general anesthetic agents during delivery by Cesarean section. Higher concentrations of enflurane may produce uterine relaxation and an increase in uterine bleeding. /Included in US product label/

US Natl Inst Health; DailyMed. Current Medication Information for ENFLURANE inhalant (April 2010). Available from, as of March 12, 2011: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=18189&CFID=55487510&CFTOKEN=245e1f8f4d81dce0-5FF4B3EE-CC3A-992F-5E755E9D27611217&jsessionid=ca30c8d8773f5f27c655


4.3 Drug Warning

A patient developed fever and acute hepatitis shortly after enflurane anesthesia. Other causes of postoperative hepatitis were excluded. Cross-sensitization with halothane may have occurred, and the enflurane hepatitis may have been aggravated by halothane hepatitis.

PMID:7426222 Danilewitz MD et al; Brit J Anesthesia 52 (11): 1151-3 (1980)


A case of mild post operative jaundice and transient renal insufficiency associated with enflurane anesthesia ... was eventually treated vigorously and successfully. ... Although other types of viral hepatitis cannot be completely ruled out, the anesthesiologist should be aware of the potential hazard of hepatic and renal toxicity attributed to enflurane...

PMID:7425324 Bernad PG et al; Anesthesie, Analgesie, Reanimation 37 (7-8): 427-8 (1980)


A case of succinylcholine and enflurane induced rhabdomyolysis and myoglobinuric acute renal failure in a mentally retarded patient is presented. The report illustrates some principles of management and the correlation of laboratory findings with the syndrome...

PMID:3476700 Lee SC et al; J Oral Maxillofac Surg 45 (9): 789-92 (1987)


Enflurane, as well as other general anesthetics, may cause a slight decrease in intellectual function for 2 or 3 days following anesthesia. As with other anesthetics, small changes in moods and symptoms may persist for several days following administration.

US Natl Inst Health; DailyMed. Current Medication Information for ENFLURANE inhalant (April 2010). Available from, as of March 12, 2011: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=18189&CFID=55487510&CFTOKEN=245e1f8f4d81dce0-5FF4B3EE-CC3A-992F-5E755E9D27611217&jsessionid=ca30c8d8773f5f27c655


For more Drug Warnings (Complete) data for Enflurane (9 total), please visit the HSDB record page.


4.4 Drug Indication

Enflurane may be used for both the induction and maintenance of general anesthesia. It can also be used to induce analgesia for vaginal delivery. Low concentrations of enflurane can also be used as an adjunct to general anesthetic drugs during delivery by Cesarean section.


5 Pharmacology and Biochemistry
5.1 Pharmacology

Enflurane rapidly induces anesthesia via the stimulation of inhibitory neural channels and the inhibition of excitatory neural channels. Muscle relaxation, obtundation of pharyngeal and laryngeal reflexes, and lowering of blood pressure are some of the main pharmacodynamic effects of this drug. Enflurane also decreases cardiac muscle contractility. High concentrations of enflurane may lead to uterine relaxation and increase the risk of uterine bleeding during delivery. Rare but clinically significant elevations in ALT may indicate hepatoxicity from the use of enflurane. In some susceptible patients, enflurane may cause malignant hyperthermia.


5.2 MeSH Pharmacological Classification

Anesthetics, Inhalation

Gases or volatile liquids that vary in the rate at which they induce anesthesia; potency; the degree of circulation, respiratory, or neuromuscular depression they produce; and analgesic effects. Inhalation anesthetics have advantages over intravenous agents in that the depth of anesthesia can be changed rapidly by altering the inhaled concentration. Because of their rapid elimination, any postoperative respiratory depression is of relatively short duration. (From AMA Drug Evaluations Annual, 1994, p173) (See all compounds classified as Anesthetics, Inhalation.)


5.3 FDA Pharmacological Classification
5.3.1 Active Moiety
ENFLURANE
5.3.2 FDA UNII
91I69L5AY5
5.3.3 Pharmacological Classes
Established Pharmacologic Class [EPC] - General Anesthetic
5.4 ATC Code

N - Nervous system

N01 - Anesthetics

N01A - Anesthetics, general

N01AB - Halogenated hydrocarbons

N01AB04 - Enflurane


5.5 Absorption, Distribution and Excretion

Absorption

Enflurane is rapidly absorbed into the circulation through the lungs. The minimum alveolar concentration is oxygen is 1.68%.


Route of Elimination

Metabolism accounts for 5-9% of enflurane elimination, sometimes causing nephrotoxicity. Excretion through the skin is believed to be minimal.


Volume of Distribution

Enflurane distributes to the brain, blood, and subcutaneous fat.


5.6 Metabolism/Metabolites

Enflurane is metabolized by the CYP2E1 enzyme in the liver to produce inorganic fluoride ions, the major metabolite of enflurane metabolism. One reference indicates that enflurane is only 2-5% eliminated after oxidative metabolism in the liver, however more recent evidence suggests that about 9% is eliminated via hepatic oxidation.


The toxicity of the chiral fluorinated volatile anesthetics halothane, enflurane, and isoflurane is closely related to their metabolism by hepatic cytochrome P450. Although individual anesthetic enantiomers have been shown to exhibit a difference in anesthetic efficacy, metabolism of anesthetic enantiomers has not been reported. Human liver enflurane metabolism to difluoromethoxydifluoroacetic acid (DFMDFA) and inorganic fluoride is catalyzed in vivo and in vitro by cytochrome P450 2E1. The purpose of this investigation was to characterize enflurane racemate and enantiomer metabolism to test the hypothesis that fluorinated ether anesthetic metabolism by cytochrome P450 2E1 exhibits substrate stereoselectivity. Enflurane metabolism by microsomes from three human livers and by microsomes containing cDNA-expressed human P450 2E1 was measured at saturating enflurane concentrations. DFMDFA was quantitated with gas chromatography-mass spectrometry by detection of the ethanolamide derivative. In microsomes from all three livers, (R)-enflurane metabolism was significantly greater than that of (S)-enflurane, whereas rates of racemic enflurane metabolism were generally between those seen for the R- and S-enantiomers. The ratio of (R)-enflurane to (S)-enflurane metabolism in the three livers studied was 2.1:1, 1.9:1, and 1.4:1. (R)-, (S)-, and racemic enflurane were all metabolized by expressed P450 2E1. The ratio of (R)-enflurane to (S)-enflurane metabolism was 1.9:1. The metabolic enantiomeric selectivity of human liver P450 2E1 for (R)-enflurane suggests that enflurane metabolism by P450 2E1 occurs by direct substrate oxidation, rather than indirectly through the generation of a P450-dependent reactive oxygen species, and supports the hypothesis that the P450 2E1 active site is somewhat restrictive and capable of stereochemical discrimination.

PMID:8689955 Garton KJ et al; Drug Metab Dispos 23 (12): 1426-30 (1995)


Difluoromethoxydifluoroacetic acid (CHF2OCF2CO2H) has been identified as a metabolite of enflurane (CHF2OCF2CHCIF) in rat liver microsomes in vitro and in human urine by gas chromatography mass spectrometry. The formation of the metabolite in rat liver microsomes was dependent upon the presence of NADPH and O2, and was inhibited when SKF 525-A or CO/O2 (8:2, v/v) were present in the reaction mixture. When the C-H bonds of the CHCIF group of enflurane or of the CHCI group of isoflurane (CHF2OCHCICF3) were replaced with a C-CI bond, virtually no fluoride ion was produced from either derivative in rat liver microsomes. These results indicate that cytochrome P-450 catalyzes the oxidative dehalogenation of CHF2OCF2CHCIF at its CHCIF group to form CHF2OCF2CO2H and chloride and fluoride ions. In contrast, the CHF2 group does not appear to be appreciably susceptible to metabolic oxidative dehalogenation...

PMID:6111426 Burke TR et al; Drug Metab Dispos 9 (1): 19-24 (1981)


Enflurane is a fluorinated volatile anesthetic, mostly eliminated unchanged in exhaled air. About 10% of inhaled enflurane undergoes oxidative metabolism in liver via mixed function oxidase.

PMID:10445395 Kolarovic J et al; Exptl Toxicol Pathol 51 (4-5): 347-51 (1999)


Fluorinated ether anesthetic hepatotoxicity and nephrotoxicity are mediated by cytochrome P450-catalyzed oxidative metabolism. Metabolism of the volatile anesthetic enflurane to inorganic fluoride ion by human liver microsomes in vitro is catalyzed predominantly by the cytochrome P450 isoform CYP2E1.

PMID:8162670 Kharasch ED et al; Clin Pharmacol Therap 55 (4): 434-40 (1994)


5.7 Biological Half-Life

Rats exposed to enflurane (100 ppm) ... in a closed all glass-system eliminated /enflurane/ from the atmosphere of the system with a half-life of 6.84 hr... . 24 hr-fasting had no influence on /the elimination half-life/. ... Pretreatment with diethyl maleate (1 mL/kg ip), dimethylsulfoxide (DMSO, 1 g/kg ip) or dithiocarb (100 mg/kg ip) prolonged the elimination half-life... . An accelerated metabolic elimination was only observed in DDT-pretreated rats exposed to enflurane; other inducers of the microsomal mixed-function oxidase system like phenobarbital or rifampicine had no significant influence on the in vivo metabolism ...

PMID:7224135 Siegers CP et al; Der Anaesthesist 30 (2): 83-7 (1981)


5.8 Mechanism of Action

The mechanism of action of enflurane is not completely established. Studies on rats indicate that enflurane binds to GABAA and glycine receptors, causing depressant effects at the ventral neural horn. It has been reported that 30% of the central nervous system depressant effects on the spinal cord after enflurane is administered are caused by the (GABA-A) receptor while binding to glycine receptors is responsible for about 20 % of the depressant effects. The relevance of these findings to humans is unknown. Other studies have found that enflurane binds to the calcium channels in the cardiac sarcoplasmic reticulum causing cardio depressant effects. Other studies support that this drug potentiates glycine receptors, which results in central nervous system depressant effects.


Renal toxicity has occasionally been observed after enflurane anesthesia. Although originally attributed to its oxidative metabolism to inorganic fluoride, serum levels of inorganic fluoride appear to be small to explain these renal effects. Formation of potentially nephrotoxic halogenated alkenes during alkaline degradation in carbon dioxide absorbers and subsequent bioactivation via the glutathione conjugation pathway may be considered as an alternative mechanism for renal toxicity. ... Alkaline degradation products of enflurane can be conjugated to thiol compounds, forming S-conjugates that could theoretically contribute to adverse renal effects observed occasionally with enflurane anesthesia. The N-acetyl-L-cysteine S-conjugates identified may be biomarkers to assess exposure of humans to alkaline degradation products of enflurane.

PMID:11465554 Orhan H et al; Anesthesiology 95 (1): 165-75 (2001)


Clinical case reports of unexplained hepatic dysfunction following enflurane and isoflurane anesthesia led to the hypothesis that oxidative metabolism of these drugs by cytochromes P-450 produces immunoreactive, covalently bound acylated protein adducts similar to those implicated in the genesis of halothane-induced hepatic necrosis. Microsomal adducts were detected by enzyme-linked immunosorbent assay and immunoblotting techniques utilizing specific anti-trifluoroacetyl (TFA) IgG hapten antibodies in rat liver following enflurane, isoflurane, or halothane administration. Preincubation of the antibodies with microsomes from halothane-pretreated rats or with 500 uM TFA-lysine, markedly inhibited adduct recognition, while preincubation with 500 uM acetyllysine had no effect. The relative amounts of immunoreactive protein adducts formed were halothane much greater than enflurane much greater than isoflurane and correlates directly with the relative extents of metabolism of these agents. These results support the view that acyl metabolites of the volatile anesthetics may become covalently bound to hepatic proteins, thus serving as antigens, and thereby account for the apparent cross-sensitization and idiosyncratic hepatotoxicity reported for these drugs.

PMID:2894942 Christ DD et al; Drug Metab Dispos 16 (1): 135-40 (1988)