These are the CNS depressant drug that brings about calming effects & induces a mild sedative effect. Major tranquillizer These are used to treat major states of mental disturbance in schizophrenia & also known as antimanic agents. e.g., Butyrophenone (Haloperidol), PTZ-Chlorpromazine Minor Tranquilizers These are used to treat milder symptoms of anxiety & tension in a healthy individual with less serious mental disorders. e.g., BDZ (Diazepam)