Depressants describe a class of pharmaceutical compounds that work by decreasing electrical activity in the central nervous system (CNS). Some depressants work by altering the chemistry of the brain to increase the amounts of chemicals that naturally block neuronal activity. Although depressants have a high potential for abuse, they are invaluable in the treatment of certain disorders.
One use of depressants is for anesthesia. More specifically, CNS depressants like barbiturates are commonly used as pre-anesthetics, which means that they are used to prepare a patient for general anesthesia. These medications rapidly put the patient to sleep, and allow for lower doses of more potent anesthetics. According to the National Institute on Drug Abuse, examples of barbiturates that can be used for this purpose include sodium pentobarbital and mephobarbital.
Another use of depressants is in the treatment of anxiety. Spine Universe and the National Institute on Drug Abuse both note that barbiturates are commonly prescribed medications for anxiety. Anxiety is marked, in part, by abnormal activity in parts of the brain. Medications that act as depressants are able to impede this anxiety-causing brain activity, thus relieving anxiety symptoms. Benzodiazepines, another class of depressants, are also able to relieve anxiety.
Benzodiazepines and barbiturates also are effective as sedatives. By depressing brain activity, these depressants are able to help patients fall asleep. Barbiturates can be used to treat sleep disorders, as can benzodiazepines. Because both medications can take hours to get out of the body, however, another class of medications have recently been developed for the treatment of sleep disorders. Zolpidem and eszopiclone are two different medications that can treat only some of the parts of the brain that respond to benzodiazepines. Because both of these medications wear off relatively quickly, they are useful for treating sleep disorders without causing any additional effects the next day.
Depressants can also be used medically as anticonvulsants. Anticonvulsants work to lower the overall activity in the brain, thus helping prevent the abnormal electrical activity that can lead to seizures and epilepsy. Barbiturates are commonly prescribed to help treat seizure-causing disorders such as epilepsy.
Sodium oxybate is a central nervous system depressant that can be used medically for the treatment of narcolepsy. Narcolepsy is marked by patients suddenly and uncontrollably falling asleep. Sodium oxybate works to prevent the sudden muscle relaxation that narcolepsy can cause. The mechanism by which sodium oxylate acts, according to Medline, is not completely understood.