Isoflurane 100% inhalation Vapour, liquid – patient leaflet, side effects, dosage

1. What Isoflurane is and what it is used for

Isoflurane is a general anaesthetic used which temporarily reduces the activity of the body’s central nervous system. This causes a complete loss of sensation in the body, including loss of consciousness allowing surgery to be carried out without pain or distress.

Isoflurane is a clear colourless liquid that when put into a special anaesthetic machine (vaporiser) becomes a gas which is mixed with oxygen and you will be breathing in the mixture. It causes you to fall into a deep, painless sleep (induction of anaesthesia). It also maintains a deep, painless sleep during which you can undergo surgery (maintenance of anaesthesia).

2. What you need to know before you use Isoflurane

Do not use Isoflurane

• if you are hypersensitive/ allergic to Isoflurane or any of the other ingredients of this medicine (listed in section 6).
• You or anyone in your family, are susceptible to rapid rise in body temperature during anaesthesia (a condition known as malignant hyperthermia). Warnings and precautions

Talk to your doctor or nurse before using Isoflurane: • You have previously been given an inhaled anaesthetic, particularly if this was more than • once over a short period (specifically in the last 3 months). Some anaesthetics can cause jaundice. • You have reacted badly after previous administration of lsoflurane or other similar anaesthetics, • e.g. you developed jaundice, fever, liver or blood problems.

• You have a disease of your liver

• You have coronary or other heart disease • You have ever had QT prolongation (prolongation of a specific time interval in an ECG) or torsade de pointes (a specific type of heart rhythm), which may also be

  associated with QT prolongation. Isoflurane has sometimes been known to cause these.

  • You have a mitochondrial disease.
  • You have raised intracranial pressure. Isoflurane may raise pressure inside your skull. This could be a problem if you have a head injury, brain tumour or another condition that already raises pressure inside your head.
  • You have low blood pressure, low blood volume or are debilitated. You may need a lower dose of Isoflurane. • You have a condition that affects muscles (a neuromuscular disease e.g. Duchenne muscular dystrophy or myasthenia gravis).
  • You suffer from bronchoconstriction (tightening of the lungs and airways leading to coughing, wheezing or shortness of breath).
  • You are suffering from any other illness other than those connected with your operation, such as severe headaches, nausea, vomiting or a condition that affects muscles (a neuromuscular disease • e.g. Duchenne muscular dystrophy or myasthenia gravis)
  • You are pregnant or breastfeeding.

Other medicines and Isoflurane

As with all drugs, it is important that you tell your ward doctor, surgeon or anaesthetist which medications you are taking. This is particularly important if you are taking the following drugs:

• Amphetamines (stimulants)
• Beta blockers (used to treat high blood pressure and certain heart conditions)
• Non-selective MAO-inhibitors (a type of anti-depressants).These should be stopped 15 days before surgery
• Isoniazid (an antibiotic used to treat tuberculosis). • Decongestant (ephedrine)
• Calcium antagonists
• Opioids and other sedatives
• Sympathomimetic agents such as isoprenaline Please tell your doctor or nurse if you are taking or have recently taken any other medicines, including medicines obtained without a prescription.

Pregnancy and breast feeding and fertility

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine Isoflurane may cause increased blood loss after operations involving the womb. If you have been breast feeding before being given Isoflurane, you should stop until the medicine is cleared from your body. Your doctor will let you know when it is safe for you to continue breast feeding.

Driving and using machines

You should not drive or use machines until your doctor advises that you are safe to do so.

Your mental alertness may be affected for 2-4 days, do not drive or operate machinery if you are affected after you have had a general anaesthetic.

3. How to use Isoflurane

Always use this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.

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IN/PI/0031/21/01 IN/PI/0031/21/01

Premedication:

Premedication drugs should be selected according to the needs of the patient. The respiratory depressant effect of Isoflurane should be taken into account. The use of anticholinergic drugs is a matter of choice, but may we advisable for inhalation induction in paediatrics.Induction:

As Isoflurane has a mild pungency, inhalation should usually be preceded by the use of a short acting barbiturate, or other intravenous induction agent, to prevent coughing. Alternatively, Isoflurane with oxygen or with an oxygen/ nitrous oxide mixture may be administered.

It is recommended that induction with Isoflurane be initiated at a concentration of 0.5%. Concentrations of 1.5-3.0% usually produce surgical anaesthesia in 7-10 minutes.

Induction of anaesthesia in children: Isoflurane is not recommended for use as an inhalation induction agent in infants and children because of the occurrence of cough, breath-holding, desaturation, increased secretions and laryngospasm.

Maintenance:

Adequate anaesthesia for surgery may be sustained with an inspired Isoflurane concentration of 1.0% to 2.5% in an oxygen/nitrous oxide mixture. Additional Isoflurane (0.5% to 1.0%) may be required when Isoflurane is given with oxygen alone.

For caesarean section, 0.5-0.75% isoflurane in a mixture of oxygen/nitrous oxide is suitable to maintain anaesthesia for this procedure.

Arterial pressure levels during maintenance tend to be inversely related to alveolar Isoflurane concentration in the absence of other complicating factors. Provided there are no other complicating factors this is probably due to peripheral vasodilation. Excessive falls in blood pressure may be due to the depth of anaesthesia and, in such circumstances, can be corrected by reducing the inspired Isoflurane concentration. Elderly:

As with other agents, lesser concentrations of isoflurane are normally required to maintain surgical anaesthesia in elderly patients. See above for MAC values related to age.

Method of Administration:

Vaporisers specially calibrated for Isoflurane should be used so that the concentration of anaesthetic can be accurately controlled.

Isoflurane is not recommended as an induction agent in children.

Undesirable Effects:

a. Summary of the safety profile

Adverse reactions encountered in the administration of Isoflurane are in general dose dependent extensions of pharmaco-physiological effects and include hypotension, respiratory depression and arrhythmias. Potential serious undesirable effects include malignant hyperthermia, hyperkalaemia, elevated serum creatine kinase, myoglobinuria, anaphylactic reactions and liver adverse reactions (see ‘Precautions’). Shivering, nausea, vomiting, ileus, agitation and delirium have been observed in the postoperative period. Cardiac arrest, bradycardia and tachycardia have been observed with general inhalation anaesthetic drugs including isoflurane.

Reports of QT prolongation, associated with torsade de pointes (in exceptional cases, fatal) have been received and ileus has been observed..

b. Tabulated summary of adverse reactions

The following table displays adverse reactions reported in clinical trials and from postmarketingexperience. Frequency cannot be estimated from the available data, therefore it is “not known”.

¹See ‘c. Description of selected adverse reactions’ below ²See 'Precautions’

³In patients undergoing induced abortion.

⁴ May cause a slight decrease in intellectual function for 2-4 days after anaesthesia. See ‘Precautions’. ⁵ Small changes in moods and symptoms may persist for up to 6 days. See ‘Precautions’. a. Description of selected adverse reactions

Transient increases in blood bilirubin, blood glucose and serum creatinine with decrease in BUN, serum cholesterol and alkaline phosphatase have been observed. As with other general anaesthetics, transient elevations in white blood count have been observed even in the absence of surgical stress. Rare reports of hypersensitivity (including dermatitis contact, rash, dyspnoea, wheezing, chest discomfort, swelling face, or anaphylactic reaction) have been received, especially in association with long-term occupational exposure to inhaled anaesthetic agents, including isoflurane. These reactions have been confirmed by clinical testing (e.g., methacholine challenge). The etiology of anaphylactic reactions experienced during inhalational anaesthetic exposure is, however, unclear because of the exposure to multiple concomitant drugs, many of which are known to cause such reactions.

Minimally raised levels of serum inorganic fluoride occur during and after isoflurane anaesthesia, due to biodegradation of the agent. It is unlikely that the low levels of serum inorganic fluoride observed (mean 4.4 μmol/l in one study) could cause renal toxicity, as these are well below the proposed threshold levels for kidney toxicity.

b. Paediatric population

Use of inhaled anaesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in paediatric patients during the post-operative period. During the induction of anaesthesia, saliva flow and tracheobronchial secretion can increase and can be the cause of laryngospasm.

c. Other special populations

Neuromuscular disease:

Use of inhaled anaesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in paediatric patients during the post-operative period. Patients with latent as well as overt neuromuscular disease, particularly Duchenne muscular dystrophy, appear to be most vulnerable. Early and aggressive intervention to treat the hyperkalaemia and resistant arrhythmias is recommended, as is subsequent evaluation for latent neuromuscular disease. Elderly:

Lesser concentrations of isoflurane are normally required to maintain surgical anaesthesia in elderly patients. Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme

Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

Overdose

As with other halogenated anaesthetics, hypotension and respiratory depression have been observed. Close monitoring of blood pressure and respiration is recommended. Supportive measures may be necessary to correct hypotension and respiratory depression resulting from excessively deep levels of anaesthesia. Pharmaceutical Precautions:

Do not store above 30°C. Keep the container tightly closed. Keep out of the sight and reach of children. Shelf Life:

5 years.

Legal Category: P

Package Information:

Isoflurane is supplied in bottles of 100 ml or 250 ml.

PL 37071/0002

Text Revised: June 2025

MA Holder:

Piramal Critical Care Limited,

Suite 4, Ground Floor,

Heathrow Boulevard - East Wing, 280 Bath Road,

West Drayton, UB7 0DQ, United Kingdom

Isoflurane will be given by a trained anaesthetist during a surgery in hospital. The anaesthetist will decide on how much Isoflurane you need depending on your age, weight and the type of operation you are having and when it is to be given. Isoflurane has a strong smell, which is quite normal and will send you to sleep quickly. Isoflurane liquid is changed to vapour (gas) in a vapouriser. You will breathe it in as a vapour. It may be used to put you to sleep before your operation or, if you are put to sleep with an injection, it may be used to maintain anaesthesia during the operation. Once the anaesthetist stops you from inhaling Isoflurane you will wake up within a few minutes.

If you have any further questions on the use of this product, ask your anaesthetist, doctor or nurse. Inducing sleep at the start of anaesthesia

Isoflurane is not recommended in infants and children for inducing sleep at the start of anaesthesia. Anaesthetist may decide to give your child medication to counter act the possible reduction in breathing and heart rate effects which may occur with the use of Isoflurane.

4. Possible side effects

Like all medicines, Isoflurane can cause side effects, although not everybody gets them. If you or your child suffer from any unusual or unexpected symptoms after an operation tell your doctor or anaesthetist IMMEDIATELY. The side effects will be managed by your surgeon or anaesthetist, as necessary, during or after the operation.

• After waking from Isoflurane anaesthesia, you may feel shivery, sick or you may vomit.
• You may experience an allergic or hypersensitivity reaction, skin rash or swelling of the face. • Isoflurane may trigger malignant hyperthermia in some people. This condition may run in families. Affected patients develop a very high temperature after receiving certain anaesthetic drugs. Intensive care is usually needed and the condition may be fatal.
• Your blood pressure may fall after being given Isoflurane, especially if you are already taking medicines to lower blood pressure. • Use of inhaled anaesthetic agents such as Isoflurane has been very rarely associated with increase in potassium levels in the blood (hyperkalaemia), resulting in abnormality of heart rhythm and death in children during the postoperative period. This event has been described in patients with latent as well as overt muscular disease, particularly Duchenne muscular dystrophy.
• You may experience breathing problems or rarely difficulty breathing (bronchospasm).
• You may experience increased heart rate and irregular heart beats (arrhythmias).
• The number of white blood cells in the blood may increase, levels of blood glucose may increase, blood levels of certain enzymes and other blood cells may be altered

• Agitation, delirium, altered mood, mental impairment, and convulsions have been reported.

  • Effects on the liver have occurred after Isoflurane anaesthesia. There have been rare reports of mild, moderate and severe liver problems such as jaundice (causing yellowing of the skin and white of the eyes) and inflammation of the liver (hepatitis) causing pain in the abdomen.
  • Isoflurane may cause increased blood loss after operations involving the womb.
  • As with other anaesthetics, small changes in moods and symptoms may persist for up to 6 days after administration.
  • Increase in blood fluoride levels (due to your body breaking down Isoflurane) with carbon monoxide levels.

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Isoflurane

Keep out of the sight and reach of children. Do not use this medicine after the expiry date which is stated on the carton 'EXP'. The expiry date refers to the last day of that month.

Storage conditions: Do not store above 30°C.

6. Contents of the pack and other information

What Isoflurane contains:

The active substance is isoflurane. There are no other ingredients.

This medicine contains fluorinated greenhouse gases. Isoflurane 100 ml bottle - Each container contains 149.6 g of isoflurane corresponding to 0.0806 tonne CO2 equivalent (global warming potential GWP = 539). Isoflurane 250 ml bottle - Each container contains 374 g of isoflurane corresponding to 0.2016 tonne CO2 equivalent (global warming potential GWP = 539). What Isoflurane looks like and contents of the pack:

Isoflurane is a colourless liquid available in 100 ml and 250 ml amber coloured glass bottles.

Marketing Authorisation Holder:

Piramal Critical Care Limited

Suite 4, Ground Floor, Heathrow Boulevard - East Wing,

280 Bath Road, West Drayton, UB7 0DQ, United Kingdom

Manufacturer:

Piramal Critical Care Limited

Suite 4, Ground Floor, Heathrow Boulevard - East Wing,

280 Bath Road, West Drayton, UB7 0DQ, United Kingdom

This leaflet was last revised in 06/2025

297 mm

74.25 mm 74.25 mm 74.25 mm 74.25 mm Printed

Perf. Line