Barbiturate antianxiety agents

Sedatives (also called hypnotics, sedative-hypnotics, minor tranquilizers, antianxiety agents) Secobarbital (barbiturate) Glutethimide (nonbarbiturate hypnotic) Diazepam (benzodiazepine antianxiety agent) Chloral hydrate (miscellaneous hypnotic) alcohol ( substance )... 

Barbiturates. The very earliest treatments for generalized anxiety were sedating barbiturates. These agents had little in the way of specific antianxiety action they merely reduced anxiety in direct proportion to their ability to sedate. Because of serious dependency and withdrawal problems (see Chapter 13) and lack of a favorable... 

Barbiturates are classified according to their duration of action (Figure 9.7). For example, thiopental [thye oh PEN tal], which acts within seconds and has a duration of action of about 30 minutes, is used in the intravenous induction of anesthesia. By contrast, phenobarbital [fee noe BAR bi tal], which has a duration of action greater than a day, is useful in the treatment of seizures (see p. 148). Pentobarbital [pen toe BAR bi tal], secobarbital [see koe BAR bi tal] and amobarbital [am oh BAR bi tal] are short-acting barbiturates, which are effective as sedative and hypnotic (but not antianxiety) agents. 

The introduction of chlordiazepoxide (Librium) into clinical medicine in 1961 ushered in the era of benzodiazepines. Most of the benzodiazepines that have reached the marketplace were selected for their effectiveness as antianxiety agents, not for their ability to depress CNS function. However, all benzodiazepines possess sedative-hypnotic properties to varying degrees these properties are extensively exploited clinically, especially to facilitate sleep and ease anxiety. Mainly because of their remarkably low capacity to lead to fatal suppression of key CNS functions, the benzodiazepines have displaced barbiturates as sedative-hypnotic agents. 

Meprobamate is an antianxiety agent. It produces CNS depressant action at multiple sites, including thalamic and limbic systems. It is indicated in the management of anxiety (see Table 9). Many drugs with diverse structures have been used for their sedative-hypnotic properties, including paraldehyde (introduced before the barbiturates), chloral hydrate, ethchlorvynol, glutethimide, methyprylon, ethinamate, and meprobamate (introduced just before the benzodiazepines). 

MAO inhibitors interfere with the detoxification of antihistamines and phenothiazines and thus prolong and intensify their central depressant and anticholinergic effects additive CNS depression and sedation may occur when tripelennamine is administered with other CNS depressants, such as alcohol, barbiturates, tranquilizers, sleeping aids, or antianxiety agents. 

Barbiturates and benzodiazepines enhance the actions of the inhibitory neurotransmitter, gamma-aminobutyric acid (Fig 3.6). Tables 3.8A, 3.8B and 3.8C compare barbiturates and benzodiazepines. Agents from both classes are effective sedative-hypnotics (sleep-inducing agents), antianxiety agents, and anticonvulsants (Table 3.9). Physicians prescribe benzodiazepines more often than barbiturates because they cause fewer side effects. 

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