Agents for Sleep Disorders

Several classes of pharmacologic agents are available for insomnia. Barbiturates are the oldest agents that have been used for insomnia and include pentobarbital, secobarbital, and amobarbital. Barbiturates are currently not recommended because of their high abuse potential (due to rapid development of tolerance) and lethal potential in overdose situations. Barbiturates potentiate the GABAergic-induced increase in chloride ion conductance at low doses, and at high doses they depress calcium-dependent action potentials. Caution should be exercised in patients with marked renal or liver dysfunction, severe respiratory disease, suicidal tendencies, or history of alcohol/drug abuse. 

Nonbarbiturate sedative-hypnotics have a similar mechanism of action as barbiturates and have high potential for tolerance, abuse, dependence, overdose, and withdrawal reactions. Chloral hydrate is still commonly used today due to its efficacy as a short-term sedative hypnotic and low cost. Chloral hydrate should not be used in patients with severe renal, hepatic, or cardiac disease. 

Antidepressant medications with sedating properties have been frequently used for insomnia. Although mirtazapine and nefazodone are still being used in patients with depression, trazodone is commonly used for the sole purpose of treating insomnia. Trazodone blocks serotonin 2A receptors and has significant sedating properties. The efficacy of trazodone as an antidepressant occurs at high doses but at lower doses it is safely used as a hypnotic. Mirtazapine and nefazodone also block serotonin 2A receptors and have occasionally been used as sedative-hypnotics. 

Zolpidem was the first omega-1 selective sedative-hypnotic to be marketed. Zaleplon is shorter acting and has faster onset of action compared with zolpidem. In patients with nocturnal awakenings, the drug has such a short duration of action that a dose can be repeated in the middle of the 

In general, sedative-hypnotics should only be used for a short period of time (7 to 10 days) and patients should be reevaluated if they are to be taken for a longer period of time. 

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