Enflurane

IUPAC nomenclature

(RS)-2-chloro-1-(difluoromethoxy)-1,1,2-trifluoroethane

Classification

Enflurane is a halogenated inhalational anesthetic.

Physiochemical Properties

Mechanism of Action

• Enflurane produces depressive effects by binding with GABA_A and glycin receptors.
• The cardio depressive effect is produced due to binding of the drug with calcium channels.
• Enflurane binds with glycine receptors which results in CNS depression.

Structure Activity Relationship

The SAR for inhaled anesthetics can be summarized as follows:

• Halogenations of the hydrocarbons and ether increases the anesthetic potency.
• Halogenations of the hydrocarbons tends to induce arrhythmia in the following order F<Cl<Br<I.
• Due to presence of asymmetric halogenated carbon in ether, they are better anesthetics.
• Halogenated methyl ethyl ethers are more stable, more potent and have better clinical profile than halogenated diethyl ether.
• Fluorination increases the stability and decreases the flammability.
• Compete halogenations of the alkane or ether decreases the anesthetic potency and increases the convulsant potency
• Presence of double bond increases chemical reactivity and toxicity.

Method of synthesis

i. Free radical chlorination of methoxy-1,1,2-tifluoro-2-chloroethane.

ii. The reaction is followed by halogen exchange in presence of HF or SbCl₅ [1]

Therapeutic Uses

Enflurane is used for:

• As an anesthetic agent

Side Effects

Side effects of enflurane are: 

• Depression of myocardial contractility
• Decrease in myocardial oxygen consumption
• Malignant hyperthermia
• Nephrotoxicity
• Acute kidney injury
• Kidney failure

MCQs 

Q.1 Match the following with correct SAR of the Inhaled anesthetics.

a) i-A, ii-C

b) i-A, ii-D

c) i-B, ii-C

d) i-B, ii-D

Q.2 Correct sequence for the True/False for correct IUPAC names of the drug can be?

• Enflurane: (RS)-2-chloro-1-(difluoromethoxy)-1,1,2-trifluoroethane
• Phenobarbitone: N,N-dimethyl-3-[2-(trifluoromethyl)-10H-phenothiazin-10-yl]propan-1-amine.
• Felbamate: 8-Chloro-11-(4-methylpiperazin-1-yl)-5H-dibenzo[b,e][1,4]diazepine
• Esmolol: (9Z)-N,N-dimethyl-9-[3-(4-methylpiperazin-1-yl)propylidene]-9H-thioxanthene-2-sulfonamide.

a) TFFF

b) FTFT

c) TTFT

d) FTTF

Q.3 Correct statement related with the solubility of the drug Enflurane from the following is?

a) Solubility is water is very good

b) Solubility in water is good

c) Solubility in water is poor

d) None of the above

Q.4 Enflurane binds with?

a) GABA_A receptors

b) Glycine receptors

c) Both a) and b)

d) None of the above

Q.5 Which amongst the following is a therapeutic use of drug Enflurane?

a) As an anesthetic agent

b) Treatment of manic phase of bipolar disorder

c) Treatment of migraine headaches

d) Treatment of Parkinson diseases

Q.6 Which of the following drug and their classification are correct?

I. Enflurane: Inhalational anesthetics

II. Carbachol: Anti-inflammatory drug

III. Arecoline: Choline ester cholinergic agonist

IV. Pilocarpine: Alkaloid cholinergic agonist

a) I

b) II, IV

c) II, III

d) , I, IV 

Q.7 Enflurane can be synthesized by halogen exchange of compound?

a) 1-(dichloromethoxy)-1,2,2-trifluoroethane

b) 1-chloro-1-(dichloromethoxy)-1,2,2-tribromoethane

c) 1-chloro-1-(dichloromethoxy)-1,2,2-triiodoethane

d) 1-chloro-1-(dichloromethoxy)-1,2,2-trifluoroethane

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ANSWERS

1-b

2-a

3-c

4-c

5-a

6-d

7-d

REFERENCES