Benzodiazepines
Benzodiazepines are antianxiety drugs that help relieve nervousness, tension, and other symptoms by slowing the central nervous system. The group of drugs known as benzodiazepines includes alprazolam (Xanax), chlordiazepoxide (Librium), diazepam (Valium), and lorazepam (Ativan). These medicines take effect fairly quickly, usually within one hour after they are taken. They are available only with a doctor's prescription, and should not be used to relieve the nervousness and tension of normal everyday life. The recommended dosage depends on the type of benzodiazepine, its strength, and the condition for which it is being taken.
While anxiety is a normal response to stress, some people have unusually high levels of anxiety that can interfere with everyday life. For these people, benzodiazepines can help bring their feelings under control. The medicine can also relieve troubling symptoms of anxiety, such as pounding heartbeat, breathing problems, irritability, nausea, and faintness.
The molecular nomenclature of these compounds is taken from the core seven-member ring, containing two nitrogen atoms, that is annulated with a benzene ring (Figure 1). Two of the best known and most widely used benzodiazepines are Librium and Valium. Both of these drugs were synthesized by Leo Sternbach of the Roche Drug Company in Nutley, New Jersey and introduced to the pharmaceutical market in the early 1960s. Each of these compounds generates emotional tranquility with usually only mild accompanying sedation of the patient. As such, this class of drugs represented a major breakthrough in the treatment of stress and anxiety disorders.
The apparent selectivity of these drugs for the relief of anxiety has attracted the attention of brain researchers. Various theories for the action of this class of compounds have been proposed. In 1977, two groups discovered that there are specific Valium binding sites in the brain. These specific receptors are suited to the molecular shape of and are able to recognize all benzodiazepines. The strength of binding is correlated with the effectiveness of the drug as an antianxiety compound, suggesting that these receptors are the active site for the drug's actions.
Further studies, by John Tallman, have shown that the effectiveness of the benzodiazepines is enhanced by gamma-aminobutyric acid (GABA) and vice versa. This compound is a common inhibitory neurotransmitter. The calming effects of the benzodiazepines are therefore connected with the inhibitory effects of GABA on neurons in various parts of the brain. What remains to be discovered is the naturally occurring compounds for which the benzodiazepines are analogues.
Unfortunately, the picture for these compounds is not without its dark side. Over time, the benzodiazepines are slightly addictive. Tolerance develops with habitual use and withdrawal symptoms occur when administration of the drug is stopped abruptly. Still, for many people, the relief from anxiety and stress provided far outweighs any potential problems.
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