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General anesthetics

Published on June 5, 2024 at 8:00 / Updated on June 21, 2024 at 8:01

Highly varied class that includes ether, chloroform, nitrous oxide (laughing gas), desflurane (Suprane®), enflurane (Ethrane®), halothane (Fluothane®), isoflurane (Forane®), propofol (Diprivan®) and sevoflurane (Sevorane®).

Classification Central nervous system depressant:
  • Refers to a substance that slows mental functions by reducing the brain's overall activity and alertness. Has a calming effect on the user.
Visual description
  • Most general anesthetics come in liquid form in bottles. Nitrous oxide is different since it is a gas that is sold in a cylinder or cartridges.
Mechanism of action
  • The exact mechanism of action of general anesthetics is unknown. They do not appear to act on a particular receptor. They most likely inhibit synaptic transmission in the central nervous system. Another proposed mechanism of action is that volatile anesthetics inhibit synaptic transmission by preventing ions from entering or exiting neurons.
Routes of administration
  • Usually inhaled from a container or a cloth saturated with the substance.
  • Nitrous oxide is different. Balloons are filled with the gas and inhaled.

Effects sought out by the user

The effects are similar to those of alcohol, barbiturates and benzodiazepines. However, they come on much more quickly and are brief. Their effects vary depending on the individual, the product and amount inhaled and how it is inhaled:

  • Euphoria (with regards to nitrous oxide, euphoria is often accompanied by laughing, hence the nickname "laughing gas")
  • Loss of inhibition
  • Transient stimulation followed by drowsiness that occasionally results in a semi-conscious state.

Common toxic effects and caused by high doses

  • Aggressive behaviour
  • Confusion
  • Disorientation
  • Dizziness
  • Drowsiness
  • Generalized muscle weakness
  • Headache
  • Irrational behaviour
  • Nausea
  • Significantly impaired judgement
  • Slurred speech
  • Uncoordinated movements
  • Vomiting

Toxic effects resulting from overdose

  • Cardiac arrest
  • Coma
  • Convulsions
  • Death
  • Decreased heartbeats
  • Irregular heart rate
  • Respiratory depression

Effects associated with chronic use

Nitrous oxide:
  • Amnesia
  • Ataxia (uncoordinated movements)
  • Bone marrow depression (blood disorders)
  • Impotence
  • Paranoid delusions
  • Peripheral polyneuropathy (numbness, paralysis) that is reversible when the user quits
  • Visual hallucinations
Other anesthetic gases (especially halothane):
  • Kidney damage
  • Liver damage
  • Weakened immune system

Tolerance (need to increase the dose to feel the same effect)

Not documented.


Psychological dependence affects only 3.7% of those who experiment with these substances.


Does not appear to be associated with any withdrawal syndrome. However, certain symptoms may occur when a substance is discontinued:

  • Excessive sweating
  • Feeling of weightlessness
  • Irritability
  • Nausea
  • Sleep disorders
  • Tremors
Onset and duration of action
Route of administrationOnset of actionPeakDuration of action
Intrapulmonary (inhaled)Almost immediateN/A About 15 minutes after stopping inhalation. Residual effects may persist for 1 to 2 hours.

Intoxication management

  • No antidote available.
  • Treatment is mainly symptomatic.
Many different street drugs are sold under the same name. Furthermore, nothing guarantees the quantity, purity or even the content of a street drug in spite of the fact that it may, in some cases, look like medication.

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