Isoflurane

Toxicity

LC50=15300 ppm/3 hrs (inhalation by rat)

Chemical properties

colourless liquid

Originator

Forane,Ohio Medical,US,1980

The Uses of Isoflurane

Isoflurane is a halogenated ether used for inhalational anesthesia. Recent studies suggest that there might be a relationship between administration of isoflurane and postoperative cognitive dysfunct ion (POCD).

The Uses of Isoflurane

Solvent and dispersant for fluorinated materials.

The Uses of Isoflurane

Isoflurane is a volatile anesthetic agent mainly used to study its interaction with the biological system.

Background

A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.

Indications

For induction and maintenance of general anesthesia.

What are the applications of Application

Isoflurane is a halogenated ether with anesthetic properties, useful solvent for dispersing fluorinated materials.

Definition

ChEBI: Isoflurane is an organofluorine compound. It has a role as an inhalation anaesthetic. It is functionally related to a methoxyethane.

Manufacturing Process

A 1-liter 3-necked stainless steel flask was fitted with a copper "Dry Ice" cold finger condenser, a stainless steel stirring shaft and gland and a copper gas inlet tube. To the flask there was then added 50 g (0.23 mol) of CF3CHClOCHCl2 and 1.5 g of SbCl5 · HF gas was then slowly bubbled through the stirred mixture which was maintained at 0°C. The reaction was run until 0.35 mol of HCl was collected, as indicated by the titration of the effluent gas which was dissolved in water. Following the fluorination 26 g of material were recovered and determined to be 90% pure by vapor phase chromatography. Fractional distillation using a 30 x 0.5 cm column packed with glass helices gave the pure product, BP 48°C to 48.5°C.

brand name

Forane (Baxter Healthcare).

Therapeutic Function

Inhalation anesthetic

Biological Functions

Isoflurane (Forane) is a structural isomer of enflurane and produces similar pharmacological properties: some analgesia, some neuromuscular blockade, and depressed respiration. In contrast, however, isoflurane is considered a particularly safe anesthetic in patients with ischemic heart disease, since cardiac output is maintained, the coronary arteries are dilated, and the myocardium does not appear to be sensitized to the effects of catecholamines. Also, blood pressure falls as a result of vasodilation, which preserves tissue blood flow. Isoflurane causes transient and mild tachycardia by direct sympathetic stimulation; this is particularly important in the management of patients with myocardial ischemia.
Unlike enflurane, isoflurane does not produce a seizurelike EEG pattern. Furthermore, the metabolic transformation of isoflurane is only one-tenth that of enflurane, so fluoride production is quite low. Among the halogenated hydrocarbons, isoflurane is one of the most popular, since it preserves cardiovascular stability and causes a low incidence of untoward effects.

General Description

Isoflurane is a volatile liquid (bp＝48.5°C) with an MAC of1.15, a blood:gas partition coefficient of 1.43 and high solubilityin fat. Isoflurane is a structural isomer of enflurane. Itis a known respiratory irritant, but less so than desflurane.Approximately 0.2% of the administered drug undergoesmetabolism, the rest is exhaled unchanged. The metabolismof isoflurane yields low levels of the nephrotoxic fluoride ionas well as a potentially hepatotoxic trifluoroacetylating compound). The relatively low concentrations ofthese compounds have resulted in very low risks of hepatotoxicityand nephrotoxicity. There have been no reports ofseizures caused by isoflurane and only transient increases inheart rate have been reported.

Biochem/physiol Actions

Isoflurane is a tandem pore potassium channel activator. It is also a very widely used anesthetic for animal research and for in vitro studies on anesthesia mechanisms.

Pharmacokinetics

Isoflurane is a general inhalation anesthetic used for induction and maintenance of general anesthesia. It induces muscle relaxation and reduces pains sensitivity by altering tissue excitability. It does so by decreasing the extent of gap junction mediated cell-cell coupling and altering the activity of the channels that underlie the action potential.

Clinical Use

Isoflurane was introduced in the United States in 1981 and is a potent anesthetic agent with many similarities to its isomer enflurane (potent, nonflammable, and intermediate blood solubility). It does produce significantly fewer cardiovascular effects than enflurane, however, and it can be used safely with epinephrine without as great a concern for arrhythmia production. Isoflurane has a more pungent odor than halothane and, thus, can cause irritation to the throat and respiratory tract, triggering coughing and laryngospasm. To overcome this problem, it often is supplemented with intravenous agents. Less than 0.2% of an administered dose is metabolized, mostly to fluoride and trifluoroacetic acid. Some minimal potential for hepatotoxicity is associated with a trifluoroacetyl halide metabolite.

Synthesis

Isoflurane is prepared by chlorination of 2,2,2-trifluoroethoxydifluoromethane, itself obtained by alkylation of trifluoroethanol with difluorochloromethane , :

Veterinary Drugs and Treatments

Isoflurane is an inhalant anesthetic that has some distinct advantages over either halothane or methoxyflurane due to its lessened myocardial depressant and catecholamine sensitizing effects, and the ability to use it safely in patients with either hepatic or renal disease. Isoflurane’s higher cost than either methoxyflurane or halothane is a disadvantage.
Horses may recover more rapidly than with halothane, but be more susceptible to anesthetic associated- myopathy.

Metabolism

Minimal