Doxepin

Administration

  • Type: Insomnia; Tricyclic Antidepressants (TCAs)
  • Dosage Forms: 10, 25, 50, 75, 100, 150; 10/mL
  • Routes of Administration: PO
  • Common Trade Names: Silenor, Zonalon, Prudoxin

Adult Dosing

Depression

  • 150-300mg PO QHS
  • start 25-75mg PO QHS; max 300mg/day
  • taper gradually to discontinue

Anxiety

  • 150-300mg PO QHS
  • start 25-75mg PO QHS; max 300mg/day
  • taper gradually to discontinue

Insomnia

  • 10-50mg PO QHS

Pediatric Dosing

Depression

  • PO:
  • Not recommended as first line medication; however some studies indicate it might be beneficial for patients with comorbid conditions.
  • Children 7 to 11 years: Limited data available; efficacy results variable: 1 to 3 mg/kg/day in single or divided doses.
  • Children ≥12 years and Adolescents: Initial: 25 to 75 mg/day at bedtime or in 2 to 3 divided doses; begin at the low end of range and gradually titrate; select patients may respond to 25 to 50 mg/day; maximum single dose: 150 mg; maximum daily dose: 300 mg/day.
    • Note: Controlled clinical trials have not shown TCAs to be superior to placebo for the treatment of depression in children and adolescents

Special Populations

Renal Dosing

  • Adult: no adjustment

Hepatic Dosing

  • Adult: not defined, caution advised

Contraindications

  • Allergy to class/drug
  • MI, acute recovery
  • glaucoma, increased IOP
  • urinary retention, prostatic hypertrophy, GI/GU obstruction
  • avoid abrupt withdrawal
  • caution if:
    • age <25 years, elderly
    • cardiovascular disease
    • seizure disorder, parkinsons
    • thyroid disease, diabetes
    • asthma
    • hepatic impairment
    • schizophrenia, bipolar disorder, alcohol abuse, electroconvulsive therapy, suicide risk
    • high environmental temperature

Adverse Reactions

Serious

  • syncope, orthostatic hypotension
  • ventricular arrhythmias, AV block, QT prolongation, torsades de pointes
  • seizures
  • MI, HTN
  • stroke
  • extrapyramidal symptoms, tardive dyskinesia
  • ataxia
  • paralytic ileus
  • IOP elevation
  • agranulocytosis, leukopenia, thrombocytopenia
  • hallucinations, psychosis, worsening depression, hypomania/mania, suicidality
  • SIADH
  • hepatitis
  • angioedema
  • hyperthermia, heat stroke
  • withdrawal symptoms if abruptly discontinued

Common

  • drowsiness, dizziness, confusion, weakness, tremor, paresthesias
  • nausea/vomiting, constipation, xerostomia
  • blurred vision
  • palpitations, tachycardia, diaphoresis, restlessness, insomnia, anxiety
  • urinary frequency, incontinence, retention
  • increased appetite, weight gain
  • libido changes, impotence, gynecomastia, galactorrhea
  • hypo/hyperglycemia
  • rash/urticarial, pruritus, photosensitivity

Pharmacology

  • Half-life: 15.3 hours (doxepin); 31 hours (metabolite)
  • Metabolism: liver; CYP450 (1A2, 2C9/19, 2D6 substrate)
  • Excretion: urine
  • Mechanism of Action: exact MOA unknown; inhibits norepinephrine and serotonin reuptake; antagonizes central H1 receptors

See Also

References