A class of DRUG that tends to depress central nervous system function and that have a calming, sedating effect on behaviour. Sedatives are also known as SEDATIVE-HYPNOTIC compounds, because of their ability to induce SLEEP. Sedatives comprise a variety of different drug classes, including BARBITURATES, BENZODIAZEPINES, ALCOHOL, and VOLATILE ANAESTHETICS. The agents from these different drug classes are remarkably varied in terms of their chemical structure and effect on brain neurochemistry.
However, they are likely to possess at least one of three properties typical of sedative drugs: (1) ION CHANNEL disruption in the neuronal MEMBRANE such that normal electrical conduction cannot occur; (2) facilitation of GABA RECEPTORS such that they become more sensitive to the inhibitory effect of GABA; (3) reduction of EXCITATORY AMINO ACID neurotransmission. Most of these compounds tend to reduce ANXIETY and induce a feeling of calm and well-being in relatively low doses, whereas higher doses can promote sleep and GENERAL ANAESTHESIA. The anti-anxiety effects are thought to be due to enhancement of inhibitory transmission in brain regions mediating EMOTION such as the LIMBIC SYSTEM; inhibition of more widespread cortical and diencephalic regions mediates the effects on sleep and CONSCIOUSNESS. Drugs in this class produce POSITIVE REINFORCEMENT and are often abused, presumably to their ability to reduce feelings of stress. COMA and death can ensue from overdose with sedatives, due to profound inhibition of BRAINSTEM respiratory and cardiovascular centres.
ANN E.KELLEY
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