Forane Side Effects Center

Last updated on RxList: 11/10/2022
Forane Side Effects Center

What Is Forane?

Forane (isoflurane) is a general inhalation anesthetic drug used to induce and maintain general anesthesia. Forane is available in generic form.

What Are Side Effects of Forane?

Forane may cause serious side effects including:

  • hives,
  • difficulty breathing,
  • swelling of your face, lips, tongue, or throat,
  • red, swollen, blistered, or peeling skin with or without fever,
  • wheezing,
  • tightness in the chest or throat,
  • unusual hoarseness,
  • confusion,
  • weakness,
  • lightheadedness,
  • dizziness,
  • numbness or tingling,
  • shortness of breath,
  • fainting,
  • slow breathing,
  • shallow breathing,
  • abnormal heartbeat,
  • muscle stiffness,
  • bluish skin color of the lips, nails, fingers, or toes,
  • fast heartbeat,
  • fast breathing,
  • fever,
  • spasm or stiffness of the jaw muscles,
  • dark urine,
  • tiredness,
  • loss of appetite,
  • upset stomach,
  • abdominal pain,
  • clay-colored stools,
  • vomiting, and
  • yellowing of the skin or eyes (jaundice)

Get medical help right away, if you have any of the symptoms listed above.

Common side effects of Forane include

Post-operatively, side effects of Forane include

  • shivering,
  • nausea,
  • vomiting, and
  • abdominal distention or
  • gas

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheadedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Forane

To induce surgical anesthesia, the dose of Forane used is inspired concentrations of 1.5 to 3.0%. Surgical levels of anesthesia may be sustained with a 1.0 to 2.5% concentration when nitrous oxide is used at the same time. An additional 0.5 to 1.0% may be required when given using oxygen alone.

What Drugs, Substances, or Supplements Interact with Forane?

Forane may interact with muscle relaxants. Tell your doctor all medications and supplements you use.

Forane During Pregnancy or Breastfeeding

During pregnancy, Forane should be used only if prescribed. It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Forane (isoflurane) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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SIDE EFFECTS

The following adverse reactions were identified from controlled clinical studies of adult and pediatric subjects exposed to isoflurane. The studies were conducted using a variety of pre-medications, other anesthetics, and surgical procedures of varying lengths.

The most serious reported adverse reactions in alphabetical order are agitation, arrhythmia, breath holding, elevated liver enzyme, hypotension and laryngospasm.

The most frequent adverse reactions (incidence ≥ 5%) described in Table 1 are agitation, breath holding, chills/shivering, cough, delirium, laryngospasm, nausea, and vomiting.

Adverse reactions with and incidence between 1% and 5% are provided in Table 2.

Adverse reactions with an incidence less than 1% are provided in Table 3.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Table 1: Adverse Reactions ≥ 5%

System Organ Class (SOC) Adverse Reaction Frequency
PSYCHIATRIC DISORDERS Delirium 6.2% (N=2830)
NERVOUS SYSTEM DISORDERS Agitation (Excitement) Induction 51.8% (N=515) 1
RESPIRATORY, THORACIC, AND MEDIASTINAL DISORDERS Breath holding Induction 23.9% (N=515) 1
Cough Induction 28.2% (N=515) 1
Laryngospasm Induction 8.0% (N=515) 1
GASTROINTESTINAL DISORDERS Nausea Recovery 15.4 % (N=2830)
Vomiting Recovery 9.5% (N=2830)
GENERAL DISORDERS AND ADMINISTRATIVE SITE CONDITIONS Chills/shivering 14.0% (N=1691)2
1 Represents patients not receiving intravenous agents or muscle relaxants for intubation (i.e., patients receiving inhalation induction).
2 Reflects the number of patients with recorded body temperature measurements.

Table 2: Adverse Reactions between 1% and 5%

System Organ Class (SOC) Adverse Reaction Frequency
NERVOUS SYSTEM DISORDERS Movement Maintenance 1.8%
(N=2830)
CARDIAC DISORDERS Ventricular arrhythmia
(Intraoperative)
Induction 2.1%
(N=2161)
Maintenance 2.7%
(N=2253)
Nodal arrhythmia
(Intraoperative)
Induction 4.0%
(N=2161)
Maintenance 1.7%
(N=2253)
Atrial arrhythmia
(Intraoperative)
Induction 1.6%
(N=2161)
Maintenance 2.2%
(N=2253)
Arrhythmia
(Postoperative)
1.1%
(N=2830)
RESPIRATORY, THORACIC, AND MEDIASTINAL DISORDERS Breath holding Maintenance 1.1%
(N=359)1
Cough Maintenance 4.2 %
(N=359)1
1 Represents patients not receiving intravenous agents or muscle relaxants for intubation (i.e., patients receiving inhalation induction).

Table 3: Adverse Reactions less than 1%

System Organ Class (SOC) Adverse Reaction Frequency
PSYCHIATRIC DISORDERS Mood changes 0.3% (N=2830)
Nightmare 0.4% (N=2175)1
NERVOUS SYSTEM DISORDERS Convulsive pattern on electroencephalogram 0.5% (N=200)2
Seizure 0.04% (N=2830)
VASCULAR DISORDERS Hypotension Postoperative 0.3% (N=2830)
Hypertension Postoperative 0.1% (N=2830)
RESPIRATORY, THORACIC, AND MEDIASTINAL DISORDERS Laryngospasm Maintenance 0.8% (N=359)3
Secretions Induction 0.2% (N=515)3
Maintenance 0.0% (N=359)3
GASTROINTESTINAL DISORDERS Vomiting Induction 0.8% (N=515)3
Retching Induction 1.0% (N=515)3
Maintenance 0.8% (N=359)3
SKIN AND SUBCUTANEOUS TISSUE DISORDERS Diaphoresis Induction 0.2% (N=515)3
Maintenance 0.0% (N=359)3
1 Reflects the number of patients interviewed by a physician in the recovery period.
2 Reflects the number of recorded electroencephalograms.
3 Represents patients not receiving intravenous agents or muscle relaxants for intubation (i.e., patients receiving inhalation induction).

The following adverse reactions were observed, but due to limited data, frequency could not be determined.

Blood and Lymphatic System Disorders: White blood cell count increased

Metabolism and Nutrition Disorders: Blood glucose increased

Psychiatric Disorders: Confused state, Nervousness

Nervous System Disorders: Ataxia; Dizziness; Drowsiness; Intellectual function decrease

Vascular Disorders: Hypotension (Intraoperative); Hypertension (Intraoperative)

Hepatobiliary Disorders: Blood bilirubin increased; Bromsulphthalein clearance decreased; Alanine aminotransferase increased; Aspartate aminotransferase increased; Blood alkaline phosphatase increased; Blood lactate dehydrogenase increased

Musculoskeletal, Connective Tissue and Bone Disorders: Myalgia

General Disorders and Administrative Site Conditions: Asthenia; Fatigue

Post-Marketing Adverse Reactions

The following adverse reactions have been reported in the post-marketing experience, listed by MedDRA System Organ Class (SOC), then by preferred term in order of decreasing severity.

Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

BLOOD AND LYMPHATIC SYSTEM DISORDERS: Carboxyhemoglobin increased

IMMUNE SYSTEM DISORDERS: Anaphylactic reaction

METABOLISM AND NUTRITION DISORDERS: Hyperkalemia in patients with underlying myopathies

PSYCHIATRIC DISORDERS: Withdrawal syndrome (following multi-day exposure; symptoms include seizure, hallucination, ataxia, agitation, confusion)

NERVOUS SYSTEM DISORDERS: Brain edema, Intracranial pressure increased, Migraine, Myoclonus, Nystagmus, Pupils unequal, Headache

CARDIAC DISORDERS: Cardiac arrest, Ventricular fibrillation, Torsade de pointes, Myocardial infarction, Myocardial ischemia, Atrioventricular block complete, Atrioventricular block second degree, Atrial fibrillation, Electrocardiogram QT prolonged, Atrioventricular block first degree, Ventricular tachycardia, Ventricular extrasystoles, Tachycardia, Bradycardia, Cardiac output decreased

VASCULAR DISORDERS: Flushing

RESPIRATORY, THORACIC, AND MEDIASTINAL DISORDERS: Apnea, Hypoxia, Bronchospasm, Airway obstruction, Respiratory depression, Hypercapnia, Stridor, Hiccough

GASTROINTESTINAL DISORDERS: Pancreatitis

HEPATOBILIARY DISORDERS: Hepatic necrosis, Hepatic failure, Hepatitis fulminant, Cholestatic hepatitis, Hepatitis, Hepatic steatosis, Jaundice, Gammaglutamyltransferase increased

SKIN AND SUBCUTANEOUS TISSUE DISORDERS: Rash

MUSCULOSKELETAL, CONNECTIVE TISSUE AND BONE DISORDERS: Rhabdomyolysis

RENAL AND URINARY DISORDERS: Acute renal failure**, Oliguria**

GENERAL DISORDERS AND ADMINISTRATION SITE CONDITIONS: Malignant hyperthermia, hypothermia

INJURY, POISONING, AND PROCEDURAL COMPLICATIONS*: Unwanted awareness during anesthesia; Dyspnea, Bronchospasm, Stridor, Cough, Dizziness, Paresthesia, Hepatic reactions, Flushing, Rash, Contact dermatitis, Erythema, Periorbital edema, Eye irritation, Conjunctival hyperemia, Headache

*All reactions categorized within this SOC, with the exception of, Unwanted awareness during anesthesia, were from occupational exposure in non-patients.
**Cases of acute renal failure and oliguria have been reported after isoflurane anesthesia. These events may be secondary to hypotension or other effects of isoflurane.

DRUG INTERACTIONS

Opioids decrease the Minimum Alveolar Concentration (MAC) of isoflurane. Opioids such as fentanyl and its analogues, when combined with isoflurane, may lead to a synergistic fall in blood pressure and respiratory rate.

Nitrous oxide decreases the MAC of isoflurane (see DOSAGE AND ADMINISTRATION).

Isoflurane potentiates the muscle relaxant effect of all muscle relaxants and decreases the required doses of neuromuscular blocking agents. In general, anesthetic concentrations of isoflurane at equilibrium reduce the ED95 of succinylcholine, atracurium, pancuronium, rocuronium and vecuronium by approximately 25 to 40% or more compared to N2O/opioid anesthesia. If added relaxation is required, supplemental doses of muscle relaxants may be used.

Isoflurane is similar to sevoflurane in the sensitization of the myocardium to arrhythmogenic effect of exogenously administered adrenaline. Doses of adrenaline greater than 5mcg/kg, when administered submucosally may produce multiple ventricular arrhythmias. Isoflurane may lead to marked hypotension in patients treated with calcium antagonists.

Concomitant use of beta blockers may exaggerate the cardiovascular effects of inhalational anesthetics, including hypotension and negative inotropic effects. Concomitant use of MAO inhibitors and inhalational anesthetics may increase the risk of hemodynamic instability during surgery or medical procedures.

Read the entire FDA prescribing information for Forane (Isoflurane)

SLIDESHOW

Digestive Disorders: Common Misconceptions See Slideshow

© Forane Patient Information is supplied by Cerner Multum, Inc. and Forane Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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