ISOSWISS

Indications

• Induction of general anesthesia
• Maintenance of general anesthesia
• Anesthesia during surgical procedures
• Anesthesia in outpatient settings

Dosage

Children: Refer to BNF for Children for specific dosing recommendations.

Adults: Induction: Initially 4-11%, adjusted according to response. Maintenance: 0.5-1% when using oxygen alone, or 1-2.5% in nitrous oxide-oxygen mixtures, administered via a calibrated vaporizer.

Mechanism of action

Isoflurane induces a reduction in junctional conductance by decreasing gap junction channel opening times and increasing gap junction channel closing times. It activates calcium-dependent ATPase in the sarcoplasmic reticulum, enhancing lipid membrane fluidity. Isoflurane also binds to multiple receptors, including the GABA receptor, large conductance Ca²⁺ activated potassium channel, glutamate receptor, and glycine receptor, contributing to its anesthetic effects.

Pharmacodynamics

Isoflurane is a general inhalation anesthetic that induces muscle relaxation and decreases pain sensitivity by altering tissue excitability. It achieves these effects by decreasing gap junction-mediated cell-cell coupling and modifying the activity of ion channels involved in action potential generation. This results in a profound anesthetic state characterized by loss of consciousness and suppression of reflexes.

Pharmacokinetics

Isoflurane is rapidly absorbed and eliminated through the lungs, with minimal metabolism occurring in the liver. Its blood-gas partition coefficient is low, which facilitates rapid induction and recovery from anesthesia. The onset of action is influenced by the concentration of isoflurane in the inspired air and the patient's ventilation status, while recovery is typically swift once administration ceases.

Contra-indications

• Susceptibility to malignant hyperthermia
• Neuromuscular disease

Adverse effects

• Agitation
• Apnoea
• Arrhythmias
• Chills
• Cough
• Dizziness
• Headache
• Hypersalivation
• Hypertension
• Hypotension
• Nausea
• Respiratory disorders
• Abdominal pain
• Asthenia
• Heart failure
• Hypokalaemia
• Malaise
• Metabolic acidosis
• Hypoxia
• Breath holding
• Cardiac arrest
• Haemorrhage
• Hepatic disorders
• Hyperkalaemia

Interactions

• Sedatives
• Analgesics

Precautions

• Should only be administered by personnel experienced in anaesthesia with adequate training
• Resuscitation equipment should be available
• Can trigger malignant hyperthermia
• Can raise intracranial pressure

Pregnancy

May depress neonatal respiration if used during delivery.

Breast-feeding

Breast-feeding can be resumed as soon as mother has recovered sufficiently from anaesthesia.

Storage

Store in a tightly closed container at room temperature, protected from light.

Formulations

• Isoflurane inhalation vapour | 250 ml
• Desflurane volatile liquid | 240 ml

Mechanism of action

Isoflurane induces a reduction in junctional conductance by decreasing gap junction channel opening times and increasing gap junction channel closing times. Isoflurane also activates calcium dependent ATPase in the sarcoplasmic reticulum by increasing the fluidity of the lipid membrane. Also appears to bind the D subunit of ATP synthase and NADH dehydogenase. Isoflurane also binds to the GABA receptor, the large conductance Ca²⁺ activated potassium channel, the glutamate receptor and the glycine receptor.

Pharmacodynamics

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.