There are at least two classes of antianxiety medications, barbituates and benzodi-azepines. Both drug classes act on the GABA neurotransmitter system. Barbituates, such as secobarbitol (Seconal) and pentobarbital (Nembutol), are the older class of drugs. Today, they are rarely prescribed as conventional antianxiety medications because of their problematic side-effect profile. Barbituates have a high risk of addiction and high lethality on overdose. They also have cardiac effects at high doses and can dangerously depress respiration (suppress breathing). Barbituates are still found to be useful in controlled settings, however, as when sedating a patient before an invasive procedure.

Benzodiazepines have largely taken the place of barbituates in the treatment of anxiety. Medications such as alprazolam (Xanax), lorazepam (Ativan), clonazepam (Klonopin), and diazepam (Valium) have far lower risk of death on overdose and tend to be less addictive than barbituates. Nonetheless, benzodiazepines can still be addictive and abrupt discontinuation of the drug can put a person into withdrawal. The drug’s half-life (amount of time needed for the drug to clear the body) influences the addiction potential. Benzodiazepines with a short half-life, such as alprazolam, have higher risk of withdrawal and addiction than those with longer half-lives, such as clonazepam.