Flumazenil
Pharmacology. Flumazenil (Romazicon) is an imidazobenzodiazepine derivative that competitively inhibits the activity of CNS benzodiazepine receptors and antagonizes the CNS effects of benzodiazepines. It has no demonstrable benzodiazepine agonist activity and no significant toxicity, even in high doses. It has no effect on alcohol or opioid receptors, and it does not reverse alcohol intoxication. Flumazenil has poor oral bioavailability (16%) owing to high first-pass effect, and it is most effective when administered parenterally. After intravenous administration, the onset of benzodiazepine reversal occurs within 1–2 minutes, with 80% response reached within 3 minutes; reversal peaks at 6–10 minutes and lasts for 1–5 hours depending on the dose of flumazenil and the degree of preexisting benzodiazepine effect. Flumazenil is eliminated by hepatic metabolism and has a terminal half-life of approximately 1 hour (41–79 minutes). Hepatic dysfunction can significantly reduce normal flumazenil clearance.
Indications
Rapid reversal of benzodiazepine overdose–induced coma and respiratory depression, both as a diagnostic aid and as a potential substitute for endotracheal intubation. Routine use of flumazenil in patients with coma of unknown etiology or with suspected but unknown mixed drug overdose is not recommended; rule out high-risk patients (see below). Lowest-risk patients include those with a known iatrogenic exposure, toddlers with an ingestion, and patients with a paradoxical response (characterized by agitation or excitement and excessive movement or restlessness) to a therapeutic dose of a benzodiazepine when reversal of effect is desired.
Postoperative or post-procedure reversal of benzodiazepine sedation.
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