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Trade names | Anexate, Lanexat, Mazicon, others |
Other names | ethyl 8-fluoro- 5,6-dihydro- 5-methyl- 6-oxo- 4H- imidazo [1,5-a] [1,4] benzodiazepine- 3-carboxylate |
AHFS/Drugs.com | Monograph |
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Routes of administration | Intranasal, intravenous |
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Pharmacokinetic data | |
Metabolism | Hepatic |
Elimination half-life | 7–15 min (initial) 20–30 min (brain) 40–80 min (terminal) |
Excretion | Urine 90–95% Feces 5–10% |
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ECHA InfoCard | 100.128.069 |
Chemical and physical data | |
Formula | C15H14FN3O3 |
Molar mass | 303.293 g·mol−1 |
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Flumazenil (also known as flumazepil, code name Ro 15-1788 [3] ) is a selective GABAA receptor antagonist [4] administered via injection, otic insertion, or intranasally. Therapeutically, it acts as both an antagonist and antidote to benzodiazepines (particularly in cases of overdose), through competitive inhibition.
It was first characterized in 1981, [5] and was first marketed in 1987 by Hoffmann-La Roche under the trade name Anexate. However, it did not receive FDA approval until December 20, 1991. The developer lost its exclusive patent rights in 2008; so at present, generic formulations of this drug are available. Intravenous flumazenil is primarily used to treat benzodiazepine overdoses and to help reverse anesthesia. Administration of flumazenil by sublingual lozenge and topical cream has also been tested. [6] [7]
Flumazenil benefits patients who become excessively drowsy after use of benzodiazepines for either diagnostic or therapeutic procedures. [8]
The drug has been used as an antidote in the treatment of benzodiazepine overdoses. [8] It reverses the effects of benzodiazepines by competitive inhibition at the benzodiazepine (BZ) recognition site on the GABA/benzodiazepine receptor complex. There are many complications that must be taken into consideration when used in the acute care setting. [8] These include lowered seizure threshold, agitation, and anxiousness. Flumazenil's short half-life requires multiple doses. Because of the potential risks of withdrawal symptoms and the drug's short half-life, patients must be carefully monitored to prevent recurrence of overdose symptoms or adverse side effects.
Flumazenil is also sometimes used after surgery to reverse the sedative effects of benzodiazepines. This is similar to naloxone's application to reverse the effect of opiates and opioids following surgery. Administration of the drug requires careful monitoring by an anesthesiologist due to potential side effects and serious risks associated with over-administeration. Likewise, post-surgical monitoring is also necessary because flumazenil can mask the apparent metabolization ("wearing off") of the drug after removal of patient life-support and monitoring equipment.
Flumazenil has been effectively used to treat overdoses of non-benzodiazepine hypnotics, such as zolpidem, zaleplon and zopiclone (also known as "Z-drugs"). [9]
It may also be effective in reducing excessive daytime sleepiness while improving vigilance in primary hypersomnias, such as idiopathic hypersomnia. [6]
The drug has also been used in hepatic encephalopathy. It may have beneficial short‐term effects in people with cirrhosis, but there is no evidence for long-term benefits. [10]
The onset of action is rapid, and effects are usually 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, up to a maximum of 3 mg per hour. It is available as a clear, colourless solution for intravenous injection, containing 500 μg in 5 mL.[ citation needed ] Additional doses may be needed within 20 to 30 minutes if evidence of oversedation reappears. [11]
Many benzodiazepines (including midazolam) have longer half-lives than flumazenil. Therefore, in cases of overdose, repeated doses of flumazenil may be required to prevent recurrent symptoms once the initial dose of flumazenil wears off.[ citation needed ]
It is hepatically metabolised to inactive compounds which are excreted in the urine. Individuals who are physically dependent on benzodiazepines may experience benzodiazepine withdrawal symptoms, including seizures, upon rapid administration of flumazenil.
It is not recommended for routine use in those with a decreased level of consciousness. [12]
In terms of drug enforcement initiatives, diversion control programs and required post-marketing surveillance of adverse events, orders for flumazenil may trigger a prescription audit to the search for benzodiazepine misuse and for clinically significant adverse reactions related to their use. [13]
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. [14]
Epileptic patients who have become tolerant to the anti-seizure effects of the benzodiazepine clonazepam became seizure-free for several days after treatment with 1.5 mg of flumazenil. [15] Similarly, patients who were dependent on high doses of benzodiazepines (median dosage 333 mg diazepam-equivalent) were able to be stabilised on a low dose of clonazepam after 7–8 days of treatment with flumazenil. [16]
Flumazenil has been tested against placebo in benzodiazepine-dependent subjects. Results showed that typical benzodiazepine withdrawal effects were reversed with few to no symptoms. [17] Flumazenil was also shown to produce significantly fewer withdrawal symptoms than saline in a randomized, placebo-controlled study with benzodiazepine-dependent subjects. Additionally, relapse rates were much lower during subsequent follow-up. [18]
In vitro studies of tissue cultured cell lines have shown that chronic treatment with flumazenil enhanced the benzodiazepine binding site where such receptors have become more numerous and uncoupling/down-regulation of GABAA has been reversed. [19] [20] [21] After long-term exposure to benzodiazepines, GABAA receptors become down-regulated and uncoupled. Growth of new receptors and recoupling after prolonged flumazenil exposure has also been observed. It is thought this may be due to increased synthesis of receptor proteins. [22]
Flumazenil was found to be more effective than placebo in reducing feelings of hostility and aggression in patients who had been free of benzodiazepines for 4–266 weeks. [23] This may suggest a role for flumazenil in treating protracted benzodiazepine withdrawal symptoms.
Low-dose, slow subcutaneous flumazenil administration is a safe procedure for patients withdrawing from long-term, high-dose benzodiazepine dependency. [24] It has a low risk of seizures even amongst those who have experienced convulsions when previously attempting benzodiazepine withdrawal. [25]
In Italy, the gold standard for treatment of high-dose benzodiazepine dependency is 8–10 days of low-dose, slowly infused flumazenil. [26] One addiction treatment centre in Italy has used flumazenil to treat over 300 patients who were dependent on high doses of benzodiazepines (up to 70 times higher than conventionally prescribed) with physicians being among the clinic's most common patients. [27]
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. [28] It also exhibits weak partial agonism of GABAA receptor complexes that contain α6-type monomers; the clinical relevance of this is unknown. [29]
Flumazenil does not antagonize all of the central nervous system effects of drugs affecting GABA-ergic neurons by means other than the benzodiazepine receptor (including ethanol, barbiturates, and most anesthetics) and does not reverse the effects of opioids. It will however antagonize the action of non-benzodiazepine z-drugs, such as zolpidem and zopiclone, because they act via the benzodiazepine site of the GABA receptor [30] - it has been used to successfully treat z-drug overdose. [30] [31] [32]
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.
Flumazenil is sold under a wide variety of brand names worldwide like Anexate, Lanexat, Mazicon, Romazicon. In India it is manufactured by Roche Bangladesh Pharmaceuticals and USAN Pharmaceuticals.[ citation needed ]
Benzodiazepines, colloquially known as "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, insomnia, and seizures. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955, and was made available in 1960 by Hoffmann–La Roche, which followed with the development of diazepam (Valium) three years later, in 1963. By 1977, benzodiazepines were the most prescribed medications globally; the introduction of selective serotonin reuptake inhibitors (SSRIs), among other factors, decreased rates of prescription, but they remain frequently used worldwide.
Diazepam, sold under the brand name Valium among others, is a medicine of the benzodiazepine family that acts as an anxiolytic. It is used to treat a range of conditions, including anxiety, seizures, alcohol withdrawal syndrome, muscle spasms, insomnia, and restless legs syndrome. It may also be used to cause memory loss during certain medical procedures. It can be taken orally, as a suppository inserted into the rectum, intramuscularly, intravenously or used as a nasal spray. When injected intravenously, effects begin in one to five minutes and last up to an hour. When taken by mouth, effects begin after 15 to 60 minutes.
Zolpidem, sold under the brand name Ambien among others, is a medication primarily used for the short-term treatment of sleeping problems. Guidelines recommend that it be used only after cognitive behavioral therapy for insomnia and after behavioral changes, such as sleep hygiene, have been tried. It decreases the time to sleep onset by about fifteen minutes and at larger doses helps people stay asleep longer. It is taken by mouth and is available in conventional tablets, sublingual tablets, or oral spray.
Depressants, colloquially known as "downers" or central nervous system (CNS) depressants, are drugs that lower neurotransmission levels, decrease the electrical activity of brain cells, or reduce arousal or stimulation in various areas of the brain. Some specific depressants do influence mood, either positively or negatively, but depressants often have no clear impact on mood. In contrast, stimulants, or "uppers", increase mental alertness, making stimulants the opposite drug class from depressants. Antidepressants are defined by their effect on mood, not on general brain activity, so they form an orthogonal category of drugs.
Clonazepam, sold under the brand name Klonopin among others, is a benzodiazepine medication used to prevent and treat anxiety disorders, seizures, bipolar mania, agitation associated with psychosis, obsessive–compulsive disorder (OCD), and akathisia. It is a long-acting tranquilizer of the benzodiazepine class. It possesses anxiolytic, anticonvulsant, sedative, hypnotic, and skeletal muscle relaxant properties. It is typically taken orally but is also used intravenously. Effects begin within one hour and last between eight and twelve hours in adults.
Zopiclone, sold under the brand name Imovane among others, is a nonbenzodiazepine, specifically a cyclopyrrolone, used to treat difficulty sleeping. Zopiclone is molecularly distinct from benzodiazepine drugs and is classed as a cyclopyrrolone. However, zopiclone increases the normal transmission of the neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system, via modulating GABAA receptors similarly to the way benzodiazepine drugs do inducing sedation but not with the anti-anxiety properties of the benzodiazepines.
Nonbenzodiazepines, sometimes referred to colloquially as Z-drugs, are a class of psychoactive, depressant, sedative, hypnotic, anxiolytic drugs that are benzodiazepine-like in uses, such as for treating insomnia and anxiety.
Clobazam, sold under the brand names Frisium, Onfi and others, is a benzodiazepine class medication that was patented in 1968. Clobazam was first synthesized in 1966 and first published in 1969. Clobazam was originally marketed as an anxioselective anxiolytic since 1970, and an anticonvulsant since 1984. The primary drug-development goal was to provide greater anxiolytic, anti-obsessive efficacy with fewer benzodiazepine-related side effects.
Quazepam, sold under the brand name Doral among others, is a relatively long-acting benzodiazepine derivative drug developed by the Schering Corporation in the 1970s. Quazepam is used for the treatment of insomnia, including sleep induction and sleep maintenance. Quazepam induces impairment of motor function and has relatively selective hypnotic and anticonvulsant properties with considerably less overdose potential than other benzodiazepines. Quazepam is an effective hypnotic which induces and maintains sleep without disruption of the sleep architecture.
Clomethiazole is a sedative and hypnotic originally developed by Hoffmann-La Roche in the 1930s. The drug is used in treating and preventing symptoms of acute alcohol withdrawal.
Alpidem, sold under the brand name Ananxyl, is a nonbenzodiazepine anxiolytic medication which was briefly used to treat anxiety disorders but is no longer marketed. It was previously marketed in France, but was discontinued due to liver toxicity. Alpidem is taken by mouth.
Lormetazepam, sold under the brand name Noctamid among others, is a drug which is a short to intermediate acting 3-hydroxy benzodiazepine derivative and temazepam analogue. It possesses hypnotic, anxiolytic, anticonvulsant, sedative, and skeletal muscle relaxant properties.
Bretazenil (Ro16-6028) is an imidazopyrrolobenzodiazepine anxiolytic drug which is derived from the benzodiazepine family, and was invented in 1988. It is most closely related in structure to the GABA antagonist flumazenil, although its effects are somewhat different. It is classified as a high-potency benzodiazepine due to its high affinity binding to benzodiazepine binding sites where it acts as a partial agonist. Its profile as a partial agonist and preclinical trial data suggests that it may have a reduced adverse effect profile. In particular bretazenil has been proposed to cause a less strong development of tolerance and withdrawal syndrome. Bretazenil differs from traditional 1,4-benzodiazepines by being a partial agonist and because it binds to α1, α2, α3, α4, α5 and α6 subunit containing GABAA receptor benzodiazepine receptor complexes. 1,4-benzodiazepines bind only to α1, α2, α3 and α5GABAA benzodiazepine receptor complexes.
Ro15-4513(IUPAC: Ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo-1,4-benzodiazepine-3-carboxylate) is a weak partial inverse agonist of the benzodiazepine class of drugs, developed by Hoffmann–La Roche in the 1980s. It acts as an inverse agonist, and can therefore be an antidote to the acute impairment caused by alcohols, including ethanol, isopropanol, tert-butyl alcohol, tert-amyl alcohol, 3-methyl-3-pentanol, methylpentynol and ethchlorvynol.
Benzodiazepine withdrawal syndrome is the cluster of signs and symptoms that may emerge when a person who has been taking benzodiazepines as prescribed develops a physical dependence on them and then reduces the dose or stops taking them without a safe taper schedule.
Benzodiazepine dependence defines a situation in which one has developed one or more of either tolerance, withdrawal symptoms, drug seeking behaviors, such as continued use despite harmful effects, and maladaptive pattern of substance use, according to the DSM-IV. In the case of benzodiazepine dependence, the continued use seems to be typically associated with the avoidance of unpleasant withdrawal reaction rather than with the pleasurable effects of the drug. Benzodiazepine dependence develops with long-term use, even at low therapeutic doses, often without the described drug seeking behavior and tolerance.
Benzodiazepine overdose describes the ingestion of one of the drugs in the benzodiazepine class in quantities greater than are recommended or generally practiced. The most common symptoms of overdose include central nervous system (CNS) depression, impaired balance, ataxia, and slurred speech. Severe symptoms include coma and respiratory depression. Supportive care is the mainstay of treatment of benzodiazepine overdose. There is an antidote, flumazenil, but its use is controversial.
Barbiturates are a class of depressant drugs that are chemically derived from barbituric acid. They are effective when used medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as well as overdose potential among other possible adverse effects. They have been used recreationally for their anti-anxiety and sedative effects, and are thus controlled in most countries due to the risks associated with such use.
In pharmacology, GABAA receptor positive allosteric modulators, also known as GABAkines or GABAA receptor potentiators, are positive allosteric modulator (PAM) molecules that increase the activity of the GABAA receptor protein in the vertebrate central nervous system.