Doxepin
Administration
- Type: Insomnia; Tricyclic antidepressant (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
- Pregnancy Rating: C
- Lactation risk: unsafe
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