Publisher Summary Drugs used for relieving anxiety, stress, worry, and fear that do not detract attention from or affect psychomotor activity of the patient are called anxiolytics or tranquilizers. Most of them have sedative and hypnotic action, and in high doses their effects are in many ways similar to barbiturate action. The primary use of tranquilizers is alleviation of emotional symptoms associated with psychoneurotic or psychosomatic disturbances, such as excitement, anxiety, worry, muscle tension, and elevated motor activity. Anxiolytics that are presently used in medicine are divided into two groups. They are benzodiazepines such as diazepam, chlordiazepoxide, chlorazepate, galazepam, lorazepam, midazolam, alprazolam, oxazepam, and prazepam, , or nonbenzodiazepine structures such as meprobamate, buspirone, chlormezanone, and hydroxyzine. The anxiolytics effect of benzodiazepines is specific and unique, and it differs from sedative and hypnotic drugs of other classes. The primary effects of benzodiazepines on the central nervous system (CNS) include relief of anxiety and worry, sedative effect, relaxation of skeletal muscle, and soporific action. They are also used to depress the respiratory system to a lesser degree than hypnotics and sedative drugs, and they also cause addiction to a lesser degree.