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Flumazenil is a GABAA receptor antagonist primarily used to treat excessive drowsiness and fatigue in post-surgery patients after sedation with GABA-based anesthesia, which are typically benzodiazepine sedatives. Flumazenil has also been used to treat benzodiazepine overdose and hypersomnia due to its effects on GABAA receptors in the brain.

How It Works

Benzodiazepine based anesthesia is often administered as a sedative for surgical procedures. Benzodiazepines bind to the GABAA receptor in the brain and works synergistically to amplify its effects. According to a study done by Erwin Sigel, the GABAA receptor is “the major inhibitory ion channel in the mammalian brain.” This means the GABA neurotransmitter is responsible for drowsiness, anti-anxiety effects, and anti-convulsive effects. Flumazenil, a GABAA antagonist, works by reversing these effects. The antagonistic effects work by blocking the GABAA “receptors in the brain and central nervous system that benzodiazepines need to reach to be active” (Drugs.com). This essentially cancels out the effect of the benzodiazepine.


The primary application of Flumazenil is to reverse the intense disorientation and drowsiness of benzodiazepine based sedatives and anesthetics following a surgical procedure. The antagonistic properties of the drug reverse the effect of the benzodiazepine, also reversing drowsiness, fatigue, and disorientation.

Flumazenil has been an effective antidote in treating benzodiazepine overdose and withdrawal in the case of substance abuse. A study by Spivey WH found that the victim of overdose may experience seizures when administered Flumazenil if they are physically dependent on benzodiazepines or if they have taken other drugs, such as cyclic antidepressants. However, the positive effects outweigh the negative effects. Flumazenil can save lives by preventing death by overdose.

Recent research by Lynn Marie Trotti has shown that Flumazenil may be effective for the treatment of hypersomnia, a sleep disorder that causes “excessive daytime sleepiness.” This only applies to hypersomnia patients who are affected due to GABA abnormalities. Theoretically, Flumazenil should return the GABA back to normal. Most of the patients in Trotti’s study reported that their symptoms improved with Flumazenil.

Possible Side Effects

  • Pain at injection site
  • Tremors
  • Dizziness
  • Sweating
  • Headache
  • Blurred vision
  • Risk of seizures
  • Shallow breathing
  • Confusion, fear, panic attack
  • Increased heart rate

Web Resources




Related Terminology

  • Benzodiazepines
  • GABA
  • Receptor Antagonist
  • Hypersomnia
  • Naloxone