What is the use of Doxepin (Sinequan)?

From the Guidelines

Doxepin is primarily used to treat depression, anxiety disorders, and insomnia, with a recommended dose of 3-6 mg for insomnia, taken 30 minutes before bedtime, as suggested by the American Academy of Sleep Medicine 1.

Uses of Doxepin

• Treatment of depression and anxiety disorders, with typical dosing ranging from 75-150 mg daily
• Treatment of insomnia, with a much lower dose of 3-6 mg used, taken 30 minutes before bedtime

Mechanism of Action

• Doxepin works by increasing levels of norepinephrine and serotonin in the brain, neurotransmitters that regulate mood and sleep

Side Effects and Precautions

• Common side effects include drowsiness, dry mouth, blurred vision, constipation, and urinary retention
• Patients should avoid alcohol while taking doxepin as it can enhance sedative effects
• Those with glaucoma, urinary retention issues, or heart conditions should use caution, and the medication should not be taken within 14 days of MAO inhibitors
• Doxepin should not be stopped abruptly but rather tapered gradually under medical supervision to avoid withdrawal symptoms
• For elderly patients, lower doses are typically recommended due to increased sensitivity to side effects

Additional Uses

• Doxepin may also be used to treat mast cell activation syndrome (MCAS), with its potent H1 & H2 antihistamine activity and tricyclic antidepressant properties 1
• However, its use in MCAS should be cautious, particularly in the elderly, due to potential cognitive decline and other side effects.

From the FDA Drug Label

Doxepin Hydrochloride Capsules, USP are recommended for the treatment of:

1. Psychoneurotic patients with depression and/or anxiety.
2. Depression and/or anxiety associated with alcoholism (not to be taken concomitantly with alcohol).
3. Depression and/or anxiety associated with organic disease (the possibility of drug interaction should be considered if the patient is receiving other drugs concomitantly).
4. Psychotic depressive disorders with associated anxiety including involutional depression and manic-depressive disorders

The use of Doxepin (Sinequan) is for the treatment of:

• Psychoneurotic patients with depression and/or anxiety
• Depression and/or anxiety associated with alcoholism, organic disease, or psychotic depressive disorders
• Anxiety and depression associated with various conditions, including involutional depression and manic-depressive disorders 2

From the Research

Use of Doxepin (Sinequan)

• Doxepin is a tricyclic antidepressant that combines antidepressant activity with a sedative effect, making it useful in treating depression, particularly in patients with sleep disturbances and anxiety 3.
• It is closely related in structure and general pharmacological properties to other tricyclic antidepressant drugs such as amitriptyline and imipramine 3.
• Doxepin has been found to be effective in improving sleep quality in patients with comorbid insomnia and anxiety disorders, with low-dose doxepin (12.5 mg/day) significantly improving sleep latency, duration, and disturbances 4.
• The effects of doxepin on sleep and depression have been evaluated in several studies, with results showing that doxepin can significantly improve sleep efficiency, decrease sleep latency, and increase total sleep time in depressed patients with sleep difficulties 5.
• Doxepin has been found to be well-tolerated, with side-effects similar to those of other tricyclic antidepressants, including dry mouth, drowsiness, and constipation 3.
• The therapeutic range of doxepin plasma concentrations is not well-established, with some studies suggesting a range of 50 to 250 ng/mL, but more research is needed to determine a definitive therapeutic range 6.
• Doxepin is not a serotonin and norepinephrine reuptake inhibitor (SNRI), but rather a tricyclic antidepressant, and its mechanism of action and clinical features are distinct from those of SNRIs 7.