CNS depressant
any of a group of drugs that, at low doses, depress the inhibitory centers of the brain. At somewhat higher doses, they depress other neural functions, slow reaction times, and lower respiration and heart rate. At still higher doses, they can induce unconsciousness, coma, and death. Examples of CNS depressants are alcohol, barbiturates, benzodiazepines, inhalants, and meprobamate. See also sedative, hypnotic, and anxiolytic drug.