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Flumazenil
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| Systematic (IUPAC) name | |
| ethyl 8-fluoro-5,6-dihydro-5-methyl-6-oxo- 4H-imidazo[1,5-a[1,4]benzodiazepine-3-carboxylate |
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| Identifiers | |
| CAS number | |
| ATC code | V03 |
| PubChem | |
| DrugBank | |
| Chemical data | |
| Formula | C15H14FN3O3 |
| Mol. mass | 303.288 g/mol |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Metabolism | Hepatic |
| Half life | 7-15 min (initial) 20-30 min (brain) 40-80 min (terminal) |
| Excretion | Urine 90-95% Feces 5-10% |
| Therapeutic considerations | |
| Pregnancy cat. |
B3(AU) C |
| Legal status | |
| Routes | Intravenous |
Flumazenil (also known as flumazepil, code name Ro 15-1788, trade names Anexate, Lanexat, Mazicon, Romazicon) is a benzodiazepine antagonist, used as an antidote in the treatment of benzodiazepine overdose. It reverses the effects of benzodiazepines by competitive inhibition at the benzodiazepine binding site on the GABAA receptor. It may also be used in hepatic encephalopathy. It was introduced in 1987 by Hoffmann-La Roche under the trade name Anexate.
The onset of action is rapid and usually effects are seen within one to two minutes. The peak effect is seen at six to ten minutes. The recommended dose for adults is 200 μg every 1-2 minutes until the effect is seen, to a maximum of 3 mg per hour. It is available as a clear, colourless solution for intravenous injection, containing 500 μg in 5 mls.
All benzodiazepines (including midazolam) have longer half-lives than flumazenil. Therefore, repeat doses of flumazenil may be required to prevent recurrent symptoms of overdosage once the initial dose of flumazenil wears off. It is hepatically metabolised to inactive compounds which are excreted in the urine. Subjects who are physically dependent on benzodiazepines may suffer benzodiazepine withdrawal symptoms, including seizure, upon administration of flumazenil.
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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. Flumazenil is a weak partial agonist in some animal models of activity, but has little or no agonist activity in man.
Flumazenil does not antagonize the central nervous system effects of drugs affecting GABA-ergic neurons by means other than the benzodiazepine receptor (including ethanol, barbiturates, or general anesthetics) and does not reverse the effects of opioids.
In animals pretreated with high doses of benzodiazepines over several weeks, Flumazenil injection elicited symptoms of benzodiazepine withdrawal, including seizures. A similar effect was seen in adult human subjects.
Pharmacodynamics
Intravenous Flumazenil has been shown to antagonize sedation, impairment of recall, psychomotor impairment and ventilatory depression produced by benzodiazepines in healthy human volunteers.
The duration and degree of reversal of sedative benzodiazepine effects are related to the dose and plasma concentrations of Flumazenil as shown in the following data from a study in normal volunteers.
PET radioligand
Radiolabeled with the radioactive isotope carbon-11 flumazenil may be used as a radioligand in neuroimaging with positron emission tomography to visualize the distribution of GABAA receptors in the human brain.[1]
References
Other
- Romazicon product information, Roche USA
External links
- Flumazenil drug label/data at Daily Med from U.S. National Library of Medicine, National Institutes of Health.
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Wikipedia content modification information:
- This page was last modified on 22 September 2008, at 03:28.
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