Doxepin is a prescription medicine that is licensed for the treatment of depression, anxiety, and insomnia. Although the brand-name version is no longer being manufactured, generic capsules are still available. The medication is thought to work for depression and anxiety by allowing certain chemicals in the brain (serotonin and norepinephrine) to stay in the brain longer. Possible side effects of doxepin include constipation, dizziness, and dry mouth.
What Is Doxepin?
Doxepin hydrochloride (Sinequan®, Silenor®) is a prescription medication that is used to treat depression (also known as major depression or clinical depression), anxiety, and insomnia.
Doxepin has long been approved for treating anxiety and depression. However, it has only recently been approved (in April 2010) for the treatment of insomnia. Only Silenor tablets (not generic doxepin products) are approved for insomnia treatment.
(Click What Is Doxepin Used For? for more information on the drug's uses, including possible off-label uses.)
Who Makes Doxepin?
Sinequan was originally made by Pfizer. However, brand-name Sinequan is no longer available. Generic doxepin is still available and is made by several manufacturers of generic medications. Silenor is made by Somaxon Pharmaceuticals, Inc.
How Does It Work?
Doxepin belongs to a class of medications called tricyclic antidepressants. It is not entirely clear how it works, but it does affect several chemicals in the brain (including serotonin and norepinephrine). It is thought that perhaps doxepin allows these chemicals to stay in the brain longer, which can help with depression symptoms and anxiety (see Anxiety Symptoms). The medication can also block histamine receptors, making it useful as an antihistamine.
It is thought that doxepin works for insomnia treatment mostly by blocking histamine receptors in the body. Specifically, it blocks a certain type of histamine receptor known as the H1 receptor. Although drugs that block H1 receptors are used for a variety of different purposes; most of them also cause some degree of sleepiness.