Benzodiazepines are widely used in medicine to treat anxiety and insomnia. These are synthetic substances normally seen as pharmaceutically-manufactured tablets, capsules and occasionally as injectables. They act as depressants of the central nervous system (CNS). Chlordiazepoxide (Librium) was the first to be synthesised in 1957 and introduced into medicine in 1961. Benzodiazepines are under international control. Diazepam (CAS 439-14-5) is one of the best known (Valium). Benzodiazepines are a group of CNS depressants which induce feelings of calm (anxiolysis), drowsiness and sleep. They act by facilitating the binding of the inhibitory neurotransmitter GABA at various GABA receptors throughout the CNS. Because they have a lower tendency to cause a potentially fatal CNS depression compared to earlier drugs such as barbiturates, benzodiazepines are widely used in medicine for the treatment of anxiety (anxiolytics) and insomnia (sedative/hypnotics), as well as other psychological conditions such as panic attacks and panic disorders. There is no clear division between anxiolytics and hypnotics, since most anxiolytics will induce sleep if taken at night and most hypnotics will sedate when taken during the day.

Benzodiazepines are usually swallowed as tablets but can be injected for both medical and non-medical purposes and there are some reports of intranasal (snorting) misuse.

Numerous synonyms and proprietary names exist for the 35 benzodiazepines under international control. When originally introduced, they were misleadingly referred to as ‘minor’ tranquillisers to distinguish them from ‘major’ tranquillisers used as anti-psychotics. Users’ terms include: benzos, blues/blueys, tranx, roche’s, mother's little helpers, duck eggs (temazepam), roofies (Rohypnol), V’s, and many others. [EUDA glossary]

__________________________

One of a group of structurally related drugs used mainly as sedatives/hypnotics, muscle relaxants, and anti-epileptics, and once referred to by the now-deprecated term "minor tranquillisers". These agents are believed to produce therapeutic effects by potentiating the action of gamma- aminobutyric acid (GABA), a major inhibitory neurotransmitter. Benzodiazepines were introduced as safer alternatives to barbiturates. They do not suppress REM sleep to the same extent as barbiturates, but have a significant potential for physical and psychological dependence and misuse.

Short-acting benzodiazepines include halazepam and triazolam, bothh with rapid onset of action; alprazolam, flunitrazepam, nitrazepam, lorazepam, and temazepam, with intermediate onset; and oxazepam, with slow onset. Profound anterograde amnesia ("blackout") and paranoia have been reported with triazolam, as well as rebound insomnia and anxiety. Many clinicians have encountered particularly difficult problems on discontinuing treatment with alprazolam.

Long-acting benzodiazepines include diazepam (with the fastest onset of action), clorazepate (also fast onset), chlordiazepoxide (intermediate onset), f1urazepam (slow onset), and prazepam (slowest onset). The long-acting benzo- diazepines may produce a cumulative disabling effect and are more likely than the short-acting agents to cause daytime sedation and motor impairment.

Even when benzodiazepines are taken in therapeutic doses, their abrupt discontinuation induces a withdrawal syndrome in up to 50% of people treated for 6 months or longer. Symptoms are more intense with shorter-acting preparations; with the long-acting benzodiazepines, withdrawal symptoms appear one or two weeks after discontinuation and last longer, but are less intense. As with other sedatives, a schedule of slow detoxification is necessary to avoid serious complications such as withdrawal seizures.

Some benzodiazepines have been used in combination with other psycho-active substances to accentuate euphoria, e.g. 40-80 mg of diazepam taken shortly before or immediately after a daily maintenance dose of methadone. Benzodiazepines are frequently misused in conjunction with alcohol or in opioid dependence (see Multiple drug use). Fatal overdose is rare with any benzodiazepine unless it is taken concurrently with alcohol or other central nervous system depressants. (WHO Lexicon of alcohol and drug terms)