Enflurane

Enflurane
Adult Indications & Dosage
Pediatric Indications & Dosage
Contraindications
Warnings & Precautions
Adverse Reactions
Drug Interactions
Use in Specific Populations
Administration & Monitoring
Overdosage
Pharmacology
Clinical Studies
How Supplied
Images
Patient Counseling Information
Precautions with Alcohol
Brand Names
Look-Alike Names

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]

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Overview

Enflurane is a general anesthetic that is FDA approved for the {{{indicationType}}} of analgesia for labor/delivery, For vaginal delivery, anesthesia - obstetric procedure, as supplement to other general anesthetic agents during cesarean section, general anesthesia.. Common adverse reactions include gastrointestinal: nausea, vomiting, musculoskeletal: involuntary movement, neurologic: shivering.

Adult Indications and Dosage

FDA-Labeled Indications and Dosage (Adult)

• Analgesia for labor/delivery, for vaginal delivery: for vaginal delivery, 0.25 to 1% concentration.
• Anesthesia - Obstetric procedure, As supplement to other general anesthetic agents during Cesarean section: during cesarean section, 0.5 to 1% concentration (to supplement other anesthetics).
• General anesthesia: induction, 2 to 4.5% concentration via vaporizer; with oxygen or combination with oxygen-nitrous oxide mixtures.
• General anesthesia: maintenance, 0.5 to 3% concentration; MAX 3%

Off-Label Use and Dosage (Adult)

Guideline-Supported Use

• General anesthesia - Surgical procedure on eye proper

Non–Guideline-Supported Use

There is limited information about Off-Label Non–Guideline-Supported Use of Enflurane in adult patients.

Pediatric Indications and Dosage

FDA-Labeled Indications and Dosage (Pediatric)

There is limited information regarding Enflurane FDA-Labeled Indications and Dosage (Pediatric) in the drug label.

Off-Label Use and Dosage (Pediatric)

Guideline-Supported Use

There is limited information about Off-Label Guideline-Supported Use of Enflurane in pediatric patients.

Non–Guideline-Supported Use

There is limited information about Off-Label Non–Guideline-Supported Use of Enflurane in pediatric patients.

Contraindications

Seizure disorders (see WARNINGS) Known sensitivity to Enflurane or other halogenated anestheticsKnown or suspected genetic susceptibility to malignant hyperthermia

Warnings

Perioperative Hyperkalemia Use of inhaled anesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in pediatric patients during the postoperative period. Patients with latent as well as overt neuromuscular disease, particularly Duchenne muscular dystrophy, appear to be most vulnerable. Concomitant use of succinylcholine has been associated with most, but not all, of these cases. These patients also experienced significant elevations in serum creatinine kinase levels and, in some cases, changes in urine consistent with myoglobinuria. Despite the similarity in presentation to malignant hyperthermia, none of these patients exhibited signs or symptoms of muscle rigidity or hypermetabolic state. Early and aggressive intervention to treat the hyperkalemia and resistant arrhythmias is recommended, as is subsequent evaluation for latent neuromuscular disease. Malignant Hyperthermia In susceptible individuals, enflurane anesthesia may trigger a skeletal muscle hypermetabolic state leading to high oxygen demand and the clinical syndrome known as malignant hyperthermia. The syndrome includes nonspecific features such as muscle rigidity, tachycardia, tachypnea, cyanosis, arrhythmias, and unstable blood pressure. (It should also be noted that many of these nonspecificsigns may appear with light anesthesia, acute hypoxia, etc. The syndrome of malignant hyperthermia secondary to enflurane appears to be rare; by March 1980, 35 cases had been reported in North America for an approximate incidence of 1:725,000 enflurane anesthetics.) An increase in overall metabolism may be reflected in an elevated temperature (which may rise rapidly early or late in the case, but usually is not the first sign of augmented metabolism) and an increased usage of the CO2 absorption system (hot cannister). PaO2 and pH may decrease, and hyperkalemia and a base deficit may appear. Treatment includes discontinuance of triggering agents (e.g., enflurane), administration of intravenous dantrolene sodium, and application of supportive therapy. Such therapy includes vigorous efforts to restore body temperature to normal, respiratory and circulatory support as indicated, and management of electrolyte-fluid-acid-base derangement. (Consult prescribing information for dantrolene sodium intravenous for additional information on patient management.) Renal failure may appear later, and urine flow should be sustained if possible.

Increasing depth of anesthesia with Enflurane may produce a change in the electroencephalogram characterized by high voltage, fast frequency, progressing through spike-dome complexes alternating with periods of electrical silence to frank seizure activity. The latter may or may not be associated with motor movement. Motor activity, when encountered, generally consists of twitching or “jerks” of various muscle groups; it is self-limiting and can be terminated by lowering the anesthetic concentration. This electroencephalographic pattern associated with deep anesthesia is exacerbated by low arterial carbon dioxide tension. A reduction in ventilation and anesthetic concentrations usually suffices to eliminate seizure activity. Cerebral blood flow and metabolism studies in normal volunteers immediately following seizure activity show no evidence of cerebral hypoxia. Mental function testing does not reveal any impairment of performance following prolonged enflurane anesthesia associated with or not associated with seizure activity.

Since levels of anesthesia may be altered easily and rapidly, only vaporizers producing predictable concentrations should be used. Hypotension and respiratory exchange can serve as a guide to depth of anesthesia. Deep levels of anesthesia may produce marked hypotension and respiratory depression When previous exposure to a halogenated anesthetic is known to have been followed by evidence of unexplained hepatic dysfunction, consideration should be given to use of an agent other than enflurane.

Adverse Reactions

Clinical Trials Experience

1. Malignant hyperthermia (see WARNINGS). 2. Motor activity exemplified by movements of various muscle groups and/or seizures may be encountered with deep levels of enflurane anesthesia, or light levels with hypocapnia 3. Hypotension, respiratory depression and hypoxia have been reported. 4. Arrhythmias, shivering, nausea and vomiting have been reported. 5. Elevation of the white blood count has been observed 6. Mild, moderate and severe liver injury, including hepatic failure, may rarely follow anesthesia with enflurane Serum transaminases may be increased and histologic evidence of injury may be found. The histologic changes are neither unique nor consistent. In several of these cases, it has not been possible to exclude enflurane as the cause or as a contributing cause to liver injury. The incidence of unexplained hepatotoxicity following the administration of enflurane is unknown, but it appears to be rare and not dose related. Enflurane has also been associated with perioperative hyperkalemia (see WARNINGS). There have been rare post-marketing reports of hepatic failure and hepatic necrosis associated with the use of potent volatile anesthetic agents, includingEnflurane. Due to the spontaneous nature of these reports, the actual incidence and relationship of Enflurane to these events cannot be established with certainty

Postmarketing Experience

There is limited information regarding Enflurane Postmarketing Experience in the drug label.

Drug Interactions

The action of nondepolarizing relaxants is augmented by enflurane. Less than the usual amounts of these drugs should be used. If the usual amounts of nondepolarizing relaxants are given, the time for recovery from neuromuscular blockade will be longer in the presence of enflurane than when halothane or nitrous oxide with a balanced technique are used

Use in Specific Populations

Pregnancy

Pregnancy Category (FDA): Reproduction studies have been performed in rats and rabbits at doses up to four times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to enflurane. There are, however, no adequate and well-controlled studies inpregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed
Pregnancy Category (AUS): There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Enflurane in women who are pregnant.

Labor and Delivery

There is no FDA guidance on use of Enflurane during labor and delivery.

Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when enflurane is administered to a nursing woman

Pediatric Use

There is no FDA guidance on the use of Enflurane in pediatric settings.

Geriatic Use

There is no FDA guidance on the use of Enflurane in geriatric settings.

Gender

There is no FDA guidance on the use of Enflurane with respect to specific gender populations.

Race

There is no FDA guidance on the use of Enflurane with respect to specific racial populations.

Renal Impairment

There is no FDA guidance on the use of Enflurane in patients with renal impairment.

Hepatic Impairment

There is no FDA guidance on the use of Enflurane in patients with hepatic impairment.

Females of Reproductive Potential and Males

There is no FDA guidance on the use of Enflurane in women of reproductive potentials and males.

Immunocompromised Patients

There is no FDA guidance one the use of Enflurane in patients who are immunocompromised.

Administration and Monitoring

Administration

There is limited information regarding Enflurane Administration in the drug label.

Monitoring

There is limited information regarding Enflurane Monitoring in the drug label.

IV Compatibility

There is limited information regarding the compatibility of Enflurane and IV administrations.

Overdosage

In the event of overdosage, or what may appear to be overdosage, the following action should be taken: Stop drug administration, establish a clear airway and initiate assisted or controlled ventilation with pure oxygen.

Pharmacology

Mechanism of Action

There is limited information regarding Enflurane Mechanism of Action in the drug label.

Structure

There is limited information regarding Enflurane Structure in the drug label.

Pharmacodynamics

There is limited information regarding Enflurane Pharmacodynamics in the drug label.

Pharmacokinetics

Biotransformation of enflurane in man results in low peak levels of serum fluoride averaging 15 μmol/L. These levels are well below the 50 μmol/L threshold level, which can produce minimal renal damage in normal subjects. However, patients chronically ingesting isoniazid or other hydrazine-containing compounds may metabolize greater amounts of enflurane. Although no significant renal dysfunction has been found thus far in such patients, peak serum fluoride levels can exceed 50 μmol/L, particularly when anesthesia goes beyond 2 MAC hours. Depression of lymphocyte transformation does notfollow prolonged enflurane anesthesia in man in the absence of surgery. Thus enflurane does not depress this aspect of the immune response.

Nonclinical Toxicology

There is limited information regarding Enflurane Nonclinical Toxicology in the drug label.

Clinical Studies

There is limited information regarding Enflurane Clinical Studies in the drug label.

How Supplied

There is limited information regarding Enflurane How Supplied in the drug label.

Storage

There is limited information regarding Enflurane Storage in the drug label.

Images

Drug Images

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Package and Label Display Panel

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Patient Counseling Information

There is limited information regarding Enflurane Patient Counseling Information in the drug label.

Precautions with Alcohol

Alcohol-Enflurane interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

Brand Names

There is limited information regarding Enflurane Brand Names in the drug label.

Look-Alike Drug Names

There is limited information regarding Enflurane Look-Alike Drug Names in the drug label.

Drug Shortage Status

Price

References

The contents of this FDA label are provided by the National Library of Medicine.