Benzodiazepine

In pharmacology, benzodiazepines (BZD) are a class of medications that are "a group of two-ring heterocyclic compounds consisting of a benzene ring fused to a diazepine ring." All benzodiazepines affect specific benzodiazepine receptors and modulate gamma-aminobutyric acid. Specific benzodiazepines also affect other neurotransmitters (e.g., clonazepam and alprazolam affect serotonin). Receptor relationships are quite complex and are discussed further below.

Uses include the treatment of anxiety disorders and alcohol withdrawal syndrome. Some are used as anticonvulsants and to treat musculoskeletal spasticity.

Selected benzodiazepines

Half life	Examples
ultra-short	cell
short (< 6 hrs)	midazolam triazolam
intermediate (6 - 24 hrs)	alprazolam estazolam lorazepam oxazepam temazepam
long (> 24 hrs)	chlordiazepoxide flurazepam diazepam quazepam.

Receptors

Part of the confusion in the receptors they affect come from the observation that what had previously been considered the GABA_A-benzodiazepine-Cl^- channel complex receptor has numerous sub-receptors, in five classes (α, β, γ, δ, ρ) with at least 16 subtypes. Benzodiazepine receptor type 1, for example, involves binding to α₁, β₂ and γ₂. The interactions among GABA, benzodiazepines, and some other classes of drugs are even more complex, in that binding to one receptor type affects other receptors. For example, certain bindings to benzodiazepine receptors will increase the rate of opening of the GABA_A receptor, potentiating the effect of both endogenous GABA and GABA released by direct GABA agonists such as baclofen.

There can be synergism in the use of various drugs that affect GABA. In musculoskeletal spasticity, as in multiple sclerosis or various disorders of spinal nerves, the first antispasticity drug prescribed is usually the GABA agonist baclofen, but it may be supplemented the BZD diazempam; diazepam can also be used as an alternative. In one study, the GABA agonists baclofen and muscimol were potentiated pain relief in rats when combined with the benzodiazepine diazepam.