Doxepin

Doxepin
Clinical data
Trade names	Sinequan, Quitaxon, Aponal, others
Other names	NSC-108160
AHFS/Drugs.com	Monograph
MedlinePlus	a682390
License data	US DailyMed: Doxepin;
Pregnancy; category	AU: C;
Routes of; administration	By mouth, topical, intravenous, intramuscular injection
Drug class	Tricyclic antidepressant (TCA)
ATC code	D04AX01 (WHO) N06AA12 (WHO);
Legal status
Legal status	AU: S4 (Prescription only); BR: Class C1 (Other controlled substances); CA: ℞-only; UK: POM (Prescription only); US: ℞-only;
Pharmacokinetic data
Bioavailability	13–45% (mean 29%)
Protein binding	76%
Metabolism	Liver (CYP2D6, CYP2C19)
Metabolites	Nordoxepin, glucuronide conjugates
Elimination half-life	Doxepin: 8–24 hours (mean 17 hours); Nordoxepin: 28–31 hours
Excretion	Kidney: ~50%; Feces: minor
Identifiers
	IUPAC name (E/Z)-3-(dibenzo[b,e]oxepin-11(6H)-ylidene)-N,N-dimethylpropan-1-amine;
CAS Number	1668-19-5 ; 1229-29-4 (hydrochloride); 3607-18-9 (cidoxepin);
PubChem CID	3158;
IUPHAR/BPS	1225;
DrugBank	DB01142 ;
ChemSpider	3046 ;
UNII	5ASJ6HUZ7D;
KEGG	D07875 ; as HCl: D00814 ;
ChEBI	CHEBI:4710 ;
ChEMBL	ChEMBL1628227 ;
PDB ligand	5EH (PDBe, RCSB PDB);
CompTox Dashboard (EPA)	DTXSID7022966 ;
Chemical and physical data
Formula	C19H21NO
Molar mass	279.383 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES CN(C)CC/C=C1C2=C(C=CC=C2)OCC3=C/1C=CC=C3;
	InChI InChI=1S/C19H21NO/c1-20(2)13-7-11-17-16-9-4-3-8-15(16)14-21-19-12-6-5-10-18(17)19/h3-6,8-12H,7,13-14H2,1-2H3 ; Key:ODQWQRRAPPTVAG-UHFFFAOYSA-N ;
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Doxepin is a medication belonging to the tricyclic antidepressant (TCA) class of drugs used to treat major depressive disorder, anxiety disorders, chronic hives, and insomnia. For hives it is a less preferred alternative to antihistamines. It has a mild to moderate benefit for sleeping problems. It is used as a cream for itchiness due to atopic dermatitis or lichen simplex chronicus.

Common side effects include sleepiness, dry mouth, constipation, nausea, and blurry vision. Serious side effects may include increased risk of suicide in those under the age of 25, mania, and urinary retention. A withdrawal syndrome may occur if the dose is rapidly decreased. Use during pregnancy and breastfeeding is not generally recommended. Although how it works for treating depression remains an area of active inquiry, it may involve increasing the levels of norepinephrine, along with blocking histamine, acetylcholine, and serotonin.

Doxepin was approved for medical use in the United States in 1969. It is available as a generic medication. In 2022, it was the 218th most commonly prescribed medication in the United States, with more than 1 million prescriptions.