Flumazenil

ADMINISTRATION ROUTES:

IV

ALTERNATIVE NAMES:

Anexate

ICU INDICATIONS:

1. Reversal of the sedative effects of benzodiazepines

PRESENTATION AND ADMINISTRATION:

IV:

0.5 mg / 5 mL of solution

Inject undiluted solution over 15 seconds preferably through a freely running IV infusion of compatible IV fluid and into a large vein.

For continuous infusion add 0.5 mg to 50 mL or 1 mg to 100 mL of compatible IV fluid, giving a concentration 0.01 mg/mL. Infuse at a rate of 0.1 - 0.4 mg/hr (10 - 40 mL/hr) and titrate to effect.

Compatible with the following IV fluids:

0.9% Sodium chloride, 5% Dextrose, Glucose and sodium chloride, Hartmanns

DOSAGE:

IV:

Bolus dosing:

0.2 mg bolus

Repeat 0.1 mg every 60 seconds to maximum of 1 mg

Infusion dosing:

Infuse at 0.1 - 0.4 mg/hr (rate 10 - 40 mL/hr of 0.01 mg/mL preparation)

If the patient fails to wake, consider alternative causes of altered conscious state

Note: in hepatic impairment initial dose remains the same but subsequent doses should be reduced in size or frequency

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose as in normal renal function

DOSAGE IN PAEDIATRICS:

IV:

Bolus dosing:

5 mcg/kg every 60 seconds to maximum 40 mcg/kg

Infusion dosing:

Infuse at 2-10 mcg/kg/hr

CLINICAL PHARMACOLOGY:

Flumazenil, an imidazobenzodiazepine derivative, antagonizes the actions of benzodiazepines on the central nervous system. Flumazenil competitively inhibits the activity at the benzodiazepine recognition site on the GABA/benzodiazepine receptor complex.

CONTRAINDICATIONS:

1. Hypersensitivity to flumazenil or benzodiazepines
2. Benzodiazepine dependence

WARNINGS:

THE USE OF FLUMAZENIL HAS BEEN ASSOCIATED WITH THE OCCURRENCE OF SEIZURES. THESE ARE MOST FREQUENT IN PATIENTS WHO HAVE BEEN ON BENZODIAZEPINES FOR LONG-TERM SEDATION OR IN OVERDOSE WHERE PATIENTS ARE ALSO SHOWING SIGNS OF SERIOUS CYCLIC ANTIDEPRESSANT TOXICITY. PRACTITIONERS SHOULD INDIVIDUALISE THE DOSAGE OF FLUMAZENIL AND BE PREPARED TO MANAGE SEIZURES.

Flumazenil should be used with caution in the ICU because of the increased risk of unrecognised benzodiazepine dependence in such settings. Flumazenil may produce convulsions in patients physically dependent on benzodiazepines.

PRECAUTIONS:

General:

Risk of Seizures

The reversal of benzodiazepine effects may be associated with the onset of seizures in certain high-risk populations. Possible risk factors for seizures include: concurrent major sedative-hypnotic drug withdrawal, recent therapy with repeated doses of parenteral benzodiazepines, myoclonic jerking or seizure activity prior to flumazenil administration in overdose cases, or concurrent cyclic anti-depressant poisoning.

Hypoventilation

Patients who have received flumazenil for the reversal of benzodiazepine effects (after conscious sedation or general anaesthesia) should be monitored for resedation, respiratory depression, or other residual benzodiazepine effects for an appropriate period (up to 120 minutes) based on the dose and duration of effect of the benzodiazepine employed.

Laboratory Tests:

No tests in addition to routine ICU tests are required

Drug/Laboratory Test Interactions:

None noted

IMPORTANT DRUG INTERACTIONS IN ICU:

Particular caution is necessary when using flumazenil in cases of mixed drug overdosage since the toxic effects (such as convulsions and cardiac dysrhythmias) of other drugs taken in overdose (especially cyclic antidepressants) may emerge with the reversal of the benzodiazepine effect by flumazenil.

ADVERSE REACTIONS:

Body as a Whole:

Fatigue (asthenia, malaise), Headache, Injection Site Pain, Injection Site Reaction (thrombophlebitis, skin abnormality, rash)

Cardiovascular System:

Cutaneous vasodilation (sweating, flushing, hot flushes)

Digestive System:

Nausea, vomiting

Nervous System:

Agitation (anxiety, nervousness, dry mouth, tremor, palpitations, insomnia, dyspnoea, hyperventilation), dizziness (vertigo, ataxia), emotional lability (crying abnormal, depersonalisation, euphoria, increased tears, depression, dysphoria, paranoia)

Special Senses:

Abnormal Vision (visual field defect, diplopia), Paraesthesia (sensation abnormal, hypoaesthesia)