Barbiturates are drugs that act as central nervous system depressants, and by virtue of this they produce a wide spectrum of effects, from mild sedation to anesthesia. They are also effective as anxiolytics, hypnotics and as anticonvulsants. They have addiction potential, both physical and psychological. Barbiturates have now largely been replaced by benzodiazepines mainly due to benzodiazepines being significantly less dangerous in overdose. Barbiturates are derivatives of barbituric acid.