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Doxepin

TCA • Brands: Sinequan

Last reviewed: 2025-09-27

General information

Indicated for: Depression and anxiety disorders; insomnia (low-dose).

Dosing & forms

  • Forms/strengths: —
  • Frequency: —
  • Food: —
  • Typical range: 75–300 mg/day (divided or nightly)

Mechanism (brief)

Tricyclic antidepressant; potent H1 blockade with serotonin/norepinephrine reuptake inhibition.

Metabolism & Half‑life

  • Metabolism: CYP2D6/CYP2C19 to nordoxepin.
  • Half‑life: ~28–31 h.

Therapeutic Drug Monitoring (TDM)

Recommended: Yes

Reference range: Combined doxepin + nordoxepin 150–250 ng/mL.

View labelExact

Monitoring highlights

  • Weight/BMI and metabolic profile — Baseline and periodically
  • TDM levels — After steady state and as clinically indicated

Sources