Flumazenil

Flumazenil is a benzodiazepine antagonist.[1][2] The primary FDA-approved clinical uses for Flumazenil are:

Treatment of benzodiazepine overdose:

• Adult, Category B, Class IIa  
• Pediatric, Category C, Class IIb 

Reversal of postoperative sedation from benzodiazepine anesthetics:

• Adult, Category B, Class IIa
• Pediatric, Category B, Class IIa

Flumazenil injection is indicated for a complete or partial reversal of the sedative effects of benzodiazepines in conscious sedation and general anesthesia in the adult and pediatric populations. Flumazenil speeds the recovery from sedation following minor surgical procedures and shortened the post-operation monitoring period for minor surgery, resulting in earlier patient discharge. Flumazenil is also indicated for the management and treatment of benzodiazepine overdose in adults. It is useful in reversing coma due to benzodiazepine overdose. Flumazenil is more effective in reversing sedation or coma in patients with benzodiazepine intoxication rather than in patients with multiple drug overdoses.[3]

Non-FDA Approved:

1. Alcohol withdrawal syndrome
2. Drug action reversal, Baclofen
3. Hepatic encephalopathy
4. Stupor, Idiopathic, recurring
5. Toxicity of drug, Cannabis

Flumazenil has not received approval from the FDA for the above uses. The advantages and disadvantages of using this drug in the non-FDA approved conditions are based on the patient's condition and the physician's judgment.

Flumazenil is a benzodiazepine antagonist. It competitively inhibits the activity of benzodiazepine and non-benzodiazepine substances that interact with benzodiazepine receptors site on the GABA/benzodiazepine receptor complex. It can also reverse the binding of benzodiazepines to benzodiazepine receptors.
The onset of action is about 1 to 2 minutes; 80% response occurs within the first 3 minutes.
The peak effect is 6 to 10 minutes after administration.
The duration range is from 19 minutes to 50 minutes, as it depends on the dose was given and benzodiazepine plasma concentrations.

Flumazenil is for intravenous (IV) infusion. The solution is stable for 24 hours if drawn into a syringe or mixed with solutions such as D5W, LR, or NS. Administer is done through a freely running IV infusion into a large vein or as a series of small injections.[4]

Dosing: Adult

FDA Dosage for management of benzodiazepine overdose

• The initial dosage of 0.2 mg IV should be given ver 30 seconds 
• If the desired level of consciousness is not obtained after 30 seconds, an additional dose of 0.3 mg IV over 30 seconds can be given
• May repeat doses of 0.5 mg IV over 30 seconds at 1-minute intervals to a maximum total cumulative dose of 3 mg
• Patients with partial response to 3 mg may require additional slow titration up to a total dose of 5 mg. If there is no response after administration of 5 mg, the primary cause of sedation is not benzodiazepine-related, and further treatment with Flumazenil will be ineffective.
• In reoccurrence, sedations repeat doses may be given at 20-minute intervals, not to exceed 1 mg (0.5 mg/minute) per dose or 3 mg/hour

FDA Dosage for Benzodiazepine reversal when used in conscious sedation or general anesthesia

• The initial dosage of 0.2 mg IV over 15 seconds 
• If the desired level of consciousness is not obtained after 45 seconds, 0.2 mg IV may be repeated at 1-minute intervals as needed. A maximum of four additional doses may be given if required.
• The maximum total cumulative dose of 1 mg
• In the reoccurrence of sedation, repeat doses may be given at 20-minute intervals, not to exceed 0.2 mg/min per dose or 3 mg/hour total.

Dosing: Pediatric (Children 1 year and older and Adolescents)

FDA Dosage for Benzodiazepine reversal when used in conscious sedation or general anesthesia

• The initial dose of 0.01 mg/kg given over 15 seconds (up to a maximum dose of 0.2 mg)
• If the desired level of consciousness is not obtained after 45 seconds, repeat 0.01 mg/kg (up to 0.2 mg) at 1-minute intervals as needed, up to four additional doses.
• The maximum total cumulative dose of 1 mg or 0.05 mg/kg, whichever is lower
• Mean total dose of 0.65 mg was administered during the clinical trial (range: 0.08 to 1 mg)

Hepatic dosing is necessary for patients with hepatic insufficiency.

Serious reaction:

• Sedation
• Neurologic effects
• Seizure
• Cardiovascular finding: Arrhythmias

Common reactions:

Cardiovascular Findings

• Bradycardia
• Tachycardia
• Hypertension
• Chest pain

Neurologic Effects

• Confusion
• Dizziness
• Headache
• Impaired cognition
• Opisthotonus
• Shivering
• Somnolence

Gastrointestinal Effects

• Nausea
• Vomiting

Immunologic Effects

• Injection site reaction

Ophthalmic Effects

• Defects of the visual field and diplopia
• Blurred vision

Otic Effects

• Hearing loss

Psychiatric Effects

• Anxiety
• Panic attack
• Psychotic disorder
• Agitation

Dermatologic Effects

• Diaphoresis
• Injection site pain 

US Black Box Warning: 

Seizures: Benzodiazepine reversal has correlations with seizures. Seizures may happen more frequently in patients who have been on benzodiazepines for long-term sedation or in patients who are showing signs of severe tricyclic antidepressant overdose. The required dosage of Flumazenil should be measured and prepared by the practitioners to manage seizures. Flumazenil use requires caution in patients relying on a benzodiazepine for seizure control.

Contraindications include:

• Hypersensitivity to Flumazenil or benzodiazepines 
• Signs of tricyclic antidepressants overdose
• Benzodiazepine use for life-threatening diseases such as control of intracranial pressure or status epilepticus 
• Mixed overdose
• Caution if psychiatric disorder- provoke panic attacks in patients with a history of panic disorder 
• Convulsions may occur in patients with a chronic dependency for benzodiazepines 
• Convulsions or alter cerebral blood flow may precipitate in patients with a head injury
• Increased risk of seizures in epileptic patients on benzodiazepine treatment for a prolonged period.
• Caution in patients with drug dependency or alcoholism due to increased frequency of benzodiazepine tolerance and dependence
• Do not use as primary treatment in patients with severe lung disease with respiratory depression secondary to benzodiazepines