Doxepin belongs to a class of drugs called tricyclic antidepressants (TCAs) that are used primarily to treat depression and anxiety. Other examples of TCAs include amitriptyline (Elavil), nortriptyline (Pamelor), desipramine (Norpramin), and several others. Depression is an all-pervasive sense of sadness and gloom. In some patients with depression, an imbalance in levels of neurotransmitters in the brain may be the cause of the depression. Neurotransmitters are chemicals that nerves use to communicate with each other. Neurotransmitters affected by doxepin include serotonin, norepinephrine, acetylcholine, and histamine. Doxepin may elevate mood by raising the levels of serotonin and norepinephrine. It also blocks the activity of acetylcholine and histamine. The FDA approved doxepin in March 1974.

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The most common side effect of doxepin is drowsiness. Drowsiness improves as therapy continues. Other side effects associated with doxepin include:

• blurred vision,
• urinary retention (difficulty urinating),
• dry mouth,
• constipation,
• weight gain or loss,
• low blood pressure when rising from a sitting position (orthostatic hypotension),
• rash,
• hives,
• rapid or irregular heart rates,
• seizures, and
• hepatitis.

Doxepin also can cause elevated pressure in the eyes of some patients withglaucoma. Doxepin may dilate pupils which may trigger an angle closure attack in a patient with angle closure glaucoma.

If antidepressants, including doxepin, are discontinued abruptly, symptoms may include:

• dizziness,
• headache,
• nausea, and
• changes in mood.

Such symptoms of withdrawal may occur even when a few doses of antidepressant are missed. Therefore, it is recommended that the dose of antidepressant be reduced gradually when therapy is discontinued.

Antidepressants increased the risk of suicidal thinking and behavior in short-term studies in children and adolescents with depression and other psychiatric disorders. Anyone considering the use of any antidepressant in a child or adolescent must balance this risk with the clinical need. Patients who are started on therapy should be closely observed for clinical worsening, suicidal thinking or behavior, and unusual changes in behavior.

The usual dose of doxepin for depression or anxiety is 25 to 300 mg daily administered at bedtime or in two or three divided doses. Doses greater than 300 mg daily are not more effective. Optimal improvement in depressive symptoms is seen after 2-3 weeks; anti-anxiety effects occur much sooner. Insomnia is treated with 3 to 6 mg daily taken 30 minutes before sleeping. Avoid taking doxepin with high fat meals because high fat meals increase the absorption of doxepin.

Tricyclic antidepressants , including doxepin, should not be taken with any of the monoamine oxidase inhibitor (MAOI) class of antidepressants (for example, isocarboxazid [Marplan], phenelzine [Nardil], tranylcypromine [Parnate], selegiline [Eldepryl], and procarbazine [Matulane]) or other drugs that inhibit monoamine oxidase such as linezolid [Zyvox] and intravenous methylene blue. Such combinations may lead to confusion, high blood pressure, tremor, hyperactivity, coma, and death. Doxepin should not be administered for at least 14 days after stopping.

Drug that affect heart rhythm such as amiodarone (Cordarone), bepridil (Vascor), and disopyramide (Norpace) should not be combined with doxepin since it also affects heart rhythm.

Cimetidine (Tagamet) increases the breakdown of doxepin by the liver and can increase doxepin blood levels, possibly causing side effects from doxepin.

There are no adequate studies of doxepin use in pregnant women.

It is not known if doxepin is secreted in breast milk. There is one report of apnea (cessation of breathing) and drowsiness occurring in a nursing infant whose mother was taking doxepin.

What preparations of doxepin are available?

Capsules: 10, 25, 50, 75, 100, 150 mg; Liquid: 10 mg/ml

How should I keep doxepin stored?

Doxepin should be stored below 30 C (86 F) in a tight, light resistant container.