indication

Used for induction and maintenance of general anesthesia in adult and pediatric patients for inpatient and outpatient surgery.

pharmacology

Sevoflurane (also called fluoromethyl) is a halogenated ether used for induction and maintenance of general anesthesia. Together with desflurane, it is replacing isoflurane and halothane in modern anesthesiology. It is often administered in nitrous oxide and pure oxygen. After desflurane it is the volatile anesthetic with the fastest onset and offset. 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.

mechanism of action

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

toxicity

LC₅₀=49881 ppm/hr (rat), LD₅₀=10.8 g/kg (rat)

biotransformation

Relatively little biotransformation, only 5% is metabolized by cytochrome P450 CYP2E1 to hexafluoroisopropanol (HFIP) with release of inorganic fluoride and CO2. No other metabolic pathways have been identified for sevoflurane.

absorption

Rapidly absorbed into circulation via the lungs, however solubility in the blood is low.

half life

15-23 hours

route of elimination

The low solubility of sevoflurane facilitates rapid elimination via the lungs. In vivo metabolism studies suggest that approximately 5% of the sevoflurane dose may be metabolized. Up to 3.5% of the sevoflurane dose appears in the urine as inorganic fluoride.