Final answer:
Barbiturates, a class of drugs derived from barbituric acid, are sub-classified by their duration of action and used for anesthesia, epilepsy treatment, and other medical needs, though they carry a risk of addiction and overdose.
Step-by-step explanation:
Barbiturates can be sub-classified into groups by their duration of action, which generally corresponds to their use as hypnotics (sleep inducers), anxiolytics (anxiety relievers), and anticonvulsants (seizure control). Barbiturates, derived from barbituric acid, have been largely replaced by other drugs such as benzodiazepines and 'Z-drugs' due to their high potential for addiction and lack of an antidote for overdose. However, barbiturates are still used in certain medical situations such as general anesthesia and the treatment of epilepsy. The risk of overdose is increased when combined with other CNS depressants, and symptoms of a barbiturate overdose include sluggishness, incoordination, and potentially coma or death.