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Indications

Flumazenil is used in hospitals to reverse the sleepiness and sedation caused by benzodiazepine medicines (such as Midazolam or Diazepam). It is used to wake patients after short procedures or anaesthesia, and to help diagnose and manage suspected benzodiazepine overdose.

How It Works

Benzodiazepines act on the brain's GABA-A receptors, the brain's main calming system. Flumazenil attaches to the same site on these receptors and blocks the benzodiazepine from acting, so alertness and breathing return. It works within one to two minutes, but its effect is shorter than that of many benzodiazepines, so sedation can come back.

Dosage and Administration

Flumazenil is an injection given into a vein only by a doctor or anaesthetist in a monitored setting. The dose is as prescribed and is given in small steps until the patient is awake enough. Patients are watched closely afterwards in case sedation returns and further doses are needed.

Interactions

• It reverses the effects of all benzodiazepines and of related sleeping medicines such as Zolpidem and Zopiclone.
• In mixed overdoses, especially with tricyclic antidepressants (such as Amitriptyline), reversing the benzodiazepine can unmask seizures and heart rhythm problems.
• It does not reverse opioids, alcohol or other sedatives.

Contraindications

• Allergy to Flumazenil.
• Patients who were given a benzodiazepine to control a life-threatening problem, such as ongoing seizures or raised pressure in the brain.
• Serious overdose with tricyclic antidepressants.

Side Effects

Common effects include nausea, vomiting, flushing, dizziness, headache, anxiety, agitation, sweating and a fast heartbeat. In people who take benzodiazepines regularly, it can bring on sudden withdrawal symptoms. Seizures can occur, especially in people with epilepsy or long-term benzodiazepine use.

Get urgent medical help if there is a fit (seizure), chest pain, a very fast or irregular heartbeat, severe confusion or panic, or if drowsiness and slow breathing return after waking.

Pregnancy and Lactation

There is little information on use in pregnancy. It is given only when the doctor judges the benefit outweighs the risk. Small amounts may pass into breast milk; the doctor will advise on when breastfeeding can resume.

Precautions and Warnings

• Sedation can return after the dose wears off, so patients must be monitored and should not drive, operate machinery or drink alcohol for at least 24 hours.
• Extra care is needed in epilepsy, head injury, liver disease, panic disorder and in long-term benzodiazepine users.
• It is not a treatment for benzodiazepine dependence.

Overdose

Flumazenil has low toxicity on its own. Too much may cause anxiety, agitation, raised muscle tone and withdrawal symptoms or seizures, which are treated in hospital.

Therapeutic Class

Benzodiazepine receptor antagonist (antidote).

Storage

Hospital medicine: store as directed on the pack, usually below 30°C, protected from light. Do not freeze. Keep out of the reach of children.