Products
Inhalation anesthetics are commercially available as volatile liquids or as gases for inhalation.
Structure and properties
Most inhalation anesthetics are halogenated ethers or hydrocarbons. Also used are inorganic compounds such as the gaseous nitrous oxide. The halogenated representatives exist as volatile liquids with a different boiling point. Because of their odor and irritant properties, not all are equally suitable for induction of anesthesia. Sevoflurane has only a mild odor. A distinctive feature is that the drugs have no excipients. Many consist of the pure active ingredient.
Effects
Inhalational anesthetics have central depressant and anesthetic properties, meaning they rapidly cause loss of consciousness after administration. Other effects include dullness, sleep promotion, amnesia, immobilization, and partial pain relief. The pharmacological effects are attributed to interaction with ion channels and neurotransmitter systems (e.g., GABA, NMDA, glycine). In the brain, they promote inhibitory and inhibit excitatory conduction. They are active both pre- and postsynaptically.
Indications
For induction and maintenance of general anesthesia during inpatient or outpatient surgical procedures.
Dosage
According to the SmPC. Drugs are usually administered by inhalation using a suitable and calibrated vaporizer. For methoxyflurane, an inhaler is used.
Active ingredients
Inhalational anesthetics include the following agents. The list shows a selection of the most important representatives: Halogenated (volatile) inhalation anesthetics:
- Desflurane (Suprane)
- Isoflurane (Forene, generic).
- Methoxyflurane (Penthrox, generic) – used as an analgesic.
- Sevoflurane (Sevorane, generic).
No longer commercially available:
- Chloroform
- Enflurane
- Halothane
Inorganic gases:
- Nitrous oxide (nitrous oxide).
- Xenon (no longer on the market)
Ether:
- Diethyl ether (ether, no longer commercially available).
Cyclic hydrocarbons:
- Cyclopropane (no longer commercially available).
Contraindications
- Hypersensitivity, including to related inhalational anesthetics.
- Predisposition to malignant hyperthermia
For complete precautions, see the drug label.
Interactions
Inhalational anesthetics usually undergo little or no metabolism and are eliminated largely unchanged via the lungs. They may be substrates of CYP450 isozymes such as CYP2E1, and corresponding drug-drug interactions are possible.
Adverse effects
The most common potential adverse effects include:
- Low blood pressure
- Cardiac arrhythmias, prolongation of the QT interval.
- Change in heart rate (bradycardia, tachycardia).
- Cough, respiratory depression, respiratory disorders
- Nausea and vomiting after the procedure
