The FDA has approved a new low-dose formulation of the tricyclic antidepressant doxepin (Silenor – Somaxon) for treatment of insomnia associated with sleep maintenance. The manufacturer claims that this dose retains the hypnotic effect of doxepin, without typical tricyclic adverse effects. Doxepin is available generically in higher-strength capsules and in a liquid formulation.

Zolpidem oral spray (Zolpimist – NovaDel/ECR), a new formulation of the oral hypnotic zolpidem tartrate (Ambien, and others), has been approved by the FDA for short-term treatment of insomnia characterized by difficulty falling asleep.

View the Expanded Table: Some Oral Drugs for Chronic Insomnia

The FDA has approved a new low-dose sublingual tablet formulation of the benzodiazepine receptor agonist zolpidem tartrate (Intermezzo – Transcept/Purdue) for treatment of insomnia due to middle-of-the-night awakening. Ambien and other zolpidem formulations available in the US are labeled for use only at bedtime.

Eszopiclone (Lunesta - Sepracor), a benzodiazepine-like drug, has been approved by the FDA for oral treatment of insomnia. It is the S-isomer of zopiclone (Imovane, and others in Canada), which has been available in other countries for almost 20 years. Unlike similar drugs such as zolpidem (Ambien) or zaleplon (Sonata), Lunesta is not being restricted in its labeling to short-term use. Like other hypnotics, eszopiclone is a schedule IV drug.

Three benzodiazepines and 16 other compounds are marketed in the USA for treatment of insomnia. Many authorities believe that insomnia is overdiagnosed and overtreated (MK Erman, ed, Sleep Disorders, Psychiatr Clin North Am, Volume 10, Dec 1987).

Estazolam (ProSom - Abbott), a triazolobenzodiazepine derivative similar in structure to alprazolam (Xanax) and triazolam (Halcion), was recently marketed in the USA for treatment of insomnia.

Quazepam (Doral - Baker Cummins, Wallace) is a trifluoroethyl benzodiazepine made by Schering and approved in 1985 by the US Food and Drug Administration for treatment of insomnia. Like other benzodiazepines, it is a Schedule IV controlled substance.Quazepam (Doral - Baker Cummins, Wallace) is a trifluoroethyl benzodiazepine made by Schering and approved in 1985 by the US Food and Drug Administration for treatment of insomnia. Like other benzodiazepines, it is a Schedule IV controlled substance.

The FDA has approved the melatonin receptor agonist tasimelteon (Hetlioz – Vanda) for treatment of non-24-hour sleep-wake disorder (non-24), which is common in totally blind persons. Tasimelteon is the first drug approved for this indication and the second melatonin receptor agonist approved for use in the US; ramelteon (Rozerem) was approved earlier for treatment of insomnia. Melatonin itself has not been approved by the FDA for any indication; it is available in the US as a dietary supplement and is promoted as a sleep aid.

On January 10, 2013, the FDA issued a news release to announce that it was requiring the manufacturers of the zolpidem-containing products Ambien, Ambien CR, Edluar and Zolpimist, which are all approved for treatment of insomnia, to lower the doses for women and to recommend in their labeling consideration of a lower dose for men. No change will be required in the dose of Intermezzo, a low-dose sublingual formulation of zolpidem for middle-of-the-night awakening, which is already recommended in a lower dose for women.