Isoflurane
Brand names: Forane
Isoflurane is a halogenated ether volatile anaesthetic agent used to induce and maintain general anaesthesia by inhalation, and occasionally for sedation in critical care.
ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.
Clinical monograph
How it works
Like other volatile agents it produces anaesthesia largely by potentiating inhibitory GABA-A and glycine receptor activity and modulating other ion channels in the central nervous system, with potency expressed as minimum alveolar concentration.
Prescribing in practice
- It is a recognised trigger for malignant hyperthermia and must be avoided in susceptible patients; dantrolene and a malignant hyperthermia protocol should be immediately available.
- It causes dose-dependent reductions in blood pressure (mainly through vasodilatation) and respiratory depression.
- Delivery requires a calibrated, agent-specific vaporiser and anaesthetic gas scavenging.
Monitoring
Monitor end-tidal agent concentration, blood pressure, oxygenation, ventilation, and temperature throughout administration.
Counselling the patient
- Drowsiness, nausea, and shivering can occur as the anaesthetic wears off.
- Inform the team of any personal or family history of adverse reactions to anaesthetic gases.
Evidence & guidelines
Use reflects long-standing anaesthetic practice; MHRA safety information on malignant hyperthermia and the SPC should be consulted.
Reference: RCoA GPAS 2023; AAGBI MH Guidelines 2020; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.