Doxepin

Generic Name: Doxepin Hydrochloride

Brand Names: Sinequan, Silenor

Drug Class: TCAs

Similar Class Drugs: Protriptyline, Desipramine

Available Dosage Forms: Oral tablet, capsule, solution, transdermal patch, and topical

What is Doxepin?

Doxepin is FDA approved for the treatment of:

-Psychoneurotic disorders such as depression and anxiety

-Depression associated with alcoholism

-Depression caused by physical distress (disease)

-Manic disorders

It has recently been approved for the treatment of insomnia in adults. In one study, low doses of Doxepin (1-6mg per day) improved sleep onset and maintenance. The patients did not report notable residual effects during the experiment.¹

The likelihood of insomnia is pronounced in children and adolescents with neurodevelopmental disorders such as autism.² A study indicated that a low dose of Doxepin (2 mg) followed by a maintenance dosage of 10mg moderately improved sleep in autistic children. Pediatric patients who were part of the trial did not show significant adverse effects (enuresis and aggression)²

There is no evidence establishing the exact mechanism of action of Doxepin. However, the noradrenergic effects witnessed with the medication have aided researchers in contriving an assumption. According to them, Doxepin inhibits the reuptake of monoamines and enhances their concentration in the neuronal synapses.³ Out of which, norepinephrine appears to be the principal target. Subsidiary effects of the drug are antagonistic to histaminic, muscarinic, and serotonergic receptors. Antihistaminic action of Doxepin aids in preventing pruritis, a common side effect reported with the use of antidepressants.

Doxepin is used off label for:³

-Prophylaxis of migraines

-Treatment of neuropathic pain

How to use Doxepin?

-Oral formulations are used to treat insomnia and mental illnesses

-Dosage depends on individual requirements

-The recommended dosage is 6 mg for adults once daily

-Take the tablet half an hour before sleeping

-Do not take the tablet for at least 3 hours after a meal

-You can dilute the prescribed dosage of liquid into 120ml (4 ounces) of water, milk, or fruit juices

-Do not mix the liquid with soda drinks

-Topical formulations are prescribed to treat pruritus

-Doctors prescribe transdermal patches for pain in urethral irritation

What are the side effects of Doxepin?

Side effects may include:

-Orthostatic hypotension

-Dry mouth

-Constipation

-Lightheadedness

-Sedation

Who should not use Doxepin?

-Anyone that is hypersensitive to the drug or any of its active ingredients

-Anyone with a history of glaucoma

-Anyone with urinary retention

-Anyone with bipolar disorder

Inform your doctor if you have the following conditions before taking Doxepin:

-Have compromised heart, liver, and kidney function

-Are pregnant, breastfeeding, or planning to get pregnant

-Are taking any medications

References

1. Scharf M, Rogowski R, Hull S, et al. Efficacy and safety of Doxepin 1 mg, 3 mg, and 6 mg in elderly patients with primary insomnia: a randomized, double-blind, placebo-controlled crossover study. J Clin Psychiatry. 2008;69(10):1557-1564. doi:10.4088/jcp.v69n1005
2. Shah YD, Stringel V, Pavkovic I, Kothare SV. Doxepin in children and adolescents with symptoms of insomnia: a single-center experience. J Clin Sleep Med. 2020;16(5):743-747. doi:10.5664/jcsm.8338
3. Almasi A, Meza CE. Doxepin. [Updated 2021 May 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542306/