Benzodiazepines, sometimes called "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, who soon followed with diazepam (Valium) 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.
Clonazepam, sold under the brand names Klonopin and Rivotril, is a medication used to prevent and treat seizures, panic disorder, anxiety disorders, and the movement disorder known as akathisia. It is a tranquilizer of the benzodiazepine class. It possesses anxiolytic, anticonvulsant, sedative, hypnotic, and skeletal muscle relaxant properties. It is typically taken by mouth. Effects begin within one hour and last between six and twelve hours.
Zopiclone, sold under the brand name Imovane among others, is a nonbenzodiazepine 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.
Nitrazepam, sold under the brand name Mogadon among others, is a hypnotic drug of the benzodiazepine class used for short-term relief from severe, disabling anxiety and insomnia. It also has sedative (calming) properties, as well as amnestic, anticonvulsant, and skeletal muscle relaxant effects.
The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor on the postsynaptic cell is selectively permeable to chloride ions (Cl−) and, to a lesser extent, bicarbonate ions (HCO3−). Depending on the membrane potential and the ionic concentration difference, this can result in ionic fluxes across the pore. If the membrane potential is higher than the equilibrium potential (also known as the reversal potential) for chloride ions, when the receptor is activated Cl− will flow into the cell. This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring at the postsynaptic cell. The reversal potential of the GABAA-mediated inhibitory postsynaptic potential (IPSP) in normal solution is −70 mV, contrasting the GABAB IPSP (-100 mV).
Quazepam, sold under 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.
Estazolam, sold under the brand name Prosom among others, is a tranquilizer medication of the triazolobenzodiazepine (TBZD) class, which are benzodiazepines (BZDs) fused with a triazole ring. It possesses anxiolytic, anticonvulsant, hypnotic, sedative and skeletal muscle relaxant properties. Estazolam is an intermediate-acting oral benzodiazepine. It is used for short-term treatment of insomnia.
Camazepam is a benzodiazepine psychoactive drug, marketed under the brand names Albego, Limpidon and Paxor. It is the dimethyl carbamate ester of temazepam, a metabolite of diazepam. While it possesses anxiolytic, anticonvulsant, skeletal muscle relaxant and hypnotic properties it differs from other benzodiazepines in that its anxiolytic properties are particularly prominent but has comparatively limited anticonvulsant, hypnotic and skeletal muscle relaxant properties.
Etizolam is a thienodiazepine derivative which is a benzodiazepine analog. The etizolam molecule differs from a benzodiazepine in that the benzene ring has been replaced by a thiophene ring and triazole ring has been fused, making the drug a thienotriazolodiazepine.
Brotizolam is a sedative-hypnotic thienotriazolodiazepine drug which is a benzodiazepine analog. It possesses anxiolytic, anticonvulsant, hypnotic, sedative and skeletal muscle relaxant properties, and is considered to be similar in effect to other short-acting hypnotic benzodiazepines such as triazolam or midazolam. It is used in the short-term treatment of severe insomnia. Brotizolam is a highly potent and short-acting hypnotic, with a typical dose ranging from 0.125 to 0.25 milligrams, which is rapidly eliminated with an average half-life of 4.4 hours.
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.
Flutazolam is a drug which is a benzodiazepine derivative. It was invented in Japan, and this is the main country in which it has been used medically. It has sedative, muscle relaxant, anticonvulsant, and anxiolytic effects similar to those produced by other benzodiazepine derivatives, and though it is around the same potency as diazepam, it produces a more marked sedation and impaired coordination. It is indicated for the treatment of insomnia. Its major active metabolite is n-desalkylflurazepam, also known as norflurazepam, which is also a principal metabolite of flurazepam. While flutazolam has a very short half-life of only 3.5 hours, n-desalkylflurazepam has a long half-life of between 47–100 hours.
Rilmazafone is a water-soluble prodrug developed in Japan. Once metabolized, rilmazafone is converted into several benzodiazepine metabolites that have sedative and hypnotic effects. These metabolites induce impairment of motor function and have hypnotic properties.
SL651498 is an anxiolytic and anticonvulsant drug used in scientific research, with a chemical structure most closely related to β-carboline derivatives such as abecarnil and gedocarnil. It has similar effects to benzodiazepine drugs, but is structurally distinct and so is classed as a nonbenzodiazepine anxiolytic.
CL-218,872 is a sedative and hypnotic drug used in scientific research. It has similar effects to sedative-hypnotic benzodiazepine drugs such as triazolam, but is structurally distinct and so is classed as a nonbenzodiazepine hypnotic.
Gamma-aminobutyric acid receptor subunit alpha-2 is a protein in humans that is encoded by the GABRA2 gene.
Deramciclane (EGIS-3886) is a non-benzodiazepine-type anxiolytic drug to treat various types of anxiety disorders. Deramciclane is a unique alternative to current anxiolytics on the market because it has a novel chemical structure and target. It acts as an antagonist at the 5-HT2A receptor, as an inverse agonist at the 5-HT2C receptor, and as a GABA reuptake inhibitor. The two serotonin receptors are G protein-coupled receptors and are two of the main excitatory serotonin receptor types. Their excitation has been implicated in anxiety and mood. Deramciclane does not affect CYP3A4 activity in metabolizing other drugs, but it is a weak inhibitor of CYP2D6. Some studies also show the drug to have moderate affinity to dopamine D2 receptors and low affinity to dopamine receptor D1. Researchers are looking for alternatives to benzodiazepines for anxiolytic use because benzodiazepine drugs have sedative and muscle relaxant side effects.
TPA-023 (MK-0777) is an anxiolytic drug with a novel chemical structure, which is used in scientific research. It has similar effects to benzodiazepine drugs, but is structurally distinct and so is classed as a nonbenzodiazepine anxiolytic. It is a subtype-selective, mixed allosteric modular at the benzodiazepine location on GABAA receptors, where it acts as a partial agonist at the α2 and α3 subtypes, but as a silent antagonist at α1 and α5 subtypes. It has primarily anxiolytic and anticonvulsant effects in animal tests, but with no sedative effects even at 50 times the effective anxiolytic dose.
The short-term effects of alcohol consumption range from a decrease in anxiety and motor skills and euphoria at lower doses to intoxication (drunkenness), to stupor, unconsciousness, anterograde amnesia, and central nervous system depression at higher doses. Cell membranes are highly permeable to alcohol, so once alcohol is in the bloodstream, it can diffuse into nearly every cell in the body.
In pharmacology, GABAA receptor positive allosteric modulators are positive allosteric modulator (PAM) molecules that increase the activity of the GABAA receptor protein in the vertebrate central nervous system.
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