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A histamine H1 antagonist

Silenor is indicated for the treatment of insomnia characterized by difficulty with sleep maintenance.1

Silenor is a histamine antagonist with a high affinity for the H1 receptor.1,2 Though the exact mechanism by which doxepin exerts its sleep maintenance effect is unknown, it is believed to be due to its antagonism of the H1 receptor.1 Histamine is one of several key wakefulness neurotransmitters.3

Silenor receptor-binding profile2
Silenor Receptor Binding Profile

Silenor has greater (subnanomolar) affinity for the histamine H1 receptor vs other receptors, although the clinical significance of receptor binding is unknown.2

Watch this brief video about the mechanism of action of Silenor.
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References:

  1. Silenor prescribing information. Somaxon Pharmaceuticals, Inc., March 2010.
  2. Mansbach RS. In vitro pharmacological profile of doxepin, a sleep-promoting histamine H1 antagonist. Eur Neuropsychopharmacol. 2008;18(suppl 4):S356-S358. Papers of the 21st ECNP Congress.
  3. Siegel JM. The neurotransmitters of sleep. J Clin Psychiatry. 2004;65(suppl 16):4-7.

Silenor is indicated for the treatment of insomnia characterized by difficulty with sleep maintenance.

IMPORTANT SAFETY INFORMATION

Silenor is contraindicated in individuals who have shown hypersensitivity to doxepin HCl, any of its inactive ingredients, or other dibenzoxepines. Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors (MAOIs). Do not administer Silenor if patient is currently on MAOIs or has used MAOIs within the past two weeks. The exact length of time may vary depending on the particular MAOI dosage and duration of treatment.

Silenor is contraindicated in individuals with untreated narrow angle glaucoma or severe urinary retention.

The failure of insomnia to remit after 7 to 10 days of treatment may indicate the presence of a primary psychiatric and/or medical illness that should be evaluated.

Complex behaviors such as "sleep-driving" (i.e., driving while not fully awake after ingestion of a hypnotic, with amnesia for the event) have been reported with hypnotics. These events can occur in hypnotic-naive as well as in hypnotic-experienced persons. Although behaviors such as "sleep-driving" may occur with hypnotics alone at therapeutic doses, the use of alcohol or other central nervous system depressants with hypnotics appears to increase the risk of such behaviors, as does the use of hypnotics at doses exceeding the maximum recommended dose. Due to the risk to the patient and the community, discontinuation of Silenor should be strongly considered for patients who report a "sleep-driving" episode. Other complex behaviors (i.e., preparing and eating food, making phone calls, or having sex) have been reported in patients who are not fully awake after taking a hypnotic. As with "sleep-driving", patients usually do not remember these events. Amnesia, anxiety and other neuro-psychiatric symptoms may occur unpredictably.

Patients should not consume alcohol with Silenor. Patients should be cautioned about potential additive effects of Silenor used in combination with CNS depressants or sedating antihistamines.

In primarily depressed patients, worsening of depression, including suicidal thoughts and actions (including completed suicides), has been reported in association with the use of hypnotics. Doxepin, the active ingredient in Silenor, is an antidepressant at doses 10- to 100-fold higher than in Silenor. Antidepressants increased the risk compared to placebo of suicidal thinking and behavior in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders. Risk from the lower dose of doxepin in Silenor can not be excluded.

Patients should not take Silenor unless they are prepared to get a full night’s sleep. After taking Silenor, patients should confine their activities to those necessary to prepare for bed. Patients should avoid engaging in hazardous activities, such as operating a motor vehicle or heavy machinery, at night after taking Silenor, and should be cautioned about potential impairment in the performance of such activities that may occur the day following ingestion.

For faster onset and to minimize the potential for next day effects, Silenor should not be taken within 3 hours of a meal.

In clinical trials, the most common treatment-emergent adverse reaction was somnolence/sedation.

Silenor has not been studied in pregnant women. Silenor is excreted in human milk after oral administration. Silenor is not approved for use in children.

Please see complete Prescribing Information before prescribing Silenor.