doxepin (Rx)

Brand and Other Names:Silenor
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Dosing & Uses


Dosage Forms & Strengths

capsule (generic)

  • 10mg
  • 25mg
  • 50mg
  • 75mg
  • 100mg
  • 150mg

tablet (Silenor)

  • 3mg
  • 6mg

oral concentrate (generic)

  • 10mg/mL


Initiate at low dose (25 mg/day); gradually titrate upward every 5-7 days

Dosage range: 25-300 mg/day PO, up to 150 mg/day as single dose

If dose exceeds 150 mg/day, divide q12hr

Dosing considerations

  • May give qHS to decrease daytime sedation

Insomnia (Silenor)

Sleep maintenance

3-6 mg PO within 30 minutes before bedtime; not to exceed 6 mg/day

Hepatic impairment/debilitated patients: 3 mg PO within 30 minutes before bedtime

Dosing considerations

  • To minimize potential for next day drowsiness, do not take within 3 hr of a meal (AUC increased by 41% and Cmax by 15% when taken with high fat meal)

Dosing Modifications

Hepatic impairment: Use lower dose and adjust gradually for depression; initiate Silenor at 3 mg daily for insomnia

<12 years old: Not recommended

Insomnia (Silenor)

Sleep maintenance

Starting dose: 3 mg PO within 30 minutes before bedtime

May increase to 6 mg PO HS if clinically indicated


Lower initial dose (ie, 10 mg/day) and adjust gradually; 10-25 mg PO qHS

May increase by 10-25 mg increments q3Day for inpatients and weekly for outpatients if tolerated

Dosing considerations

Avoid; strong anticholinergic and sedative effects; may cause orthostatic hypotension (Beers criteria)

Consider alternatives; if must use, initiate with lower initial dose

May cause confusion and oversedation in elderly



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            Adverse Effects

            Frequency Not Defined

            Sedation, fatigue, weakness, lethargy

            Dry mouth


            Blurred vision





            Nausea, vomiting


            Confusion, extrapyramidal symptoms (EPS), dizziness, paresthesia

            Orthostatic hypotension, ECG changes, tachycardia

            Increased LFTs


            Sexual dysfunction










            Black Box Warnings

            In short-term studies, antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults (<24 years) taking antidepressants for major depressive disorders and other psychiatric illnesses

            This increase was not seen in patients >24 years; a slight decrease in suicidal thinking was seen in adults >65 years

            In children and young adults, risks must be weighed against the benefits of taking antidepressants

            Patients should be monitored closely for changes in behavior, clinical worsening, and suicidal tendencies; this should be done during initial 1-2 months of therapy and dosage adjustments

            The patient’s family should communicate any abrupt changes in behavior to the healthcare provider

            Worsening behavior and suicidal tendencies that are not part of the presenting symptoms may require discontinuation of therapy

            This drug is not approved for use in pediatric patients



            Untreated narrow-angle glaucoma

            Severe urinary retention

            Within 14 days of MAO inhibitors


            Use caution in BPH, urinary retention, decreased GI motility, hyperthyroidism, brain tumor, diabetes, hepatic impairment, cardiovascular disease, mania/hypomania, respiratory disease, and seizure disorders

            Clinical worsening and suicidal ideation may occur despite medication in adolescents and young adults (aged 18-24 years)

            Risk of anticholinergic side effects

            Risk of mydriasis; may trigger angle closure attack in patients with angle closure glaucoma with anatomically narrow angles without a patent iridectomy

            CNS depressant; can impair alertness and motor coordination; avoid use with other CNS depressants (eg, alcohol)

            Overdose may cause EKG QRS widening and risk of dysrhythmias

            Protect capsules and oral concentrate from direct sunlight

            Prescriptions should be written for smallest quantity consistent with good patient care; patient's family or caregiver should alert healthcare professional about emergence of suicidality and related behaviors including agitation, panic attacks, irritability, impulsivity, mania, and insomnia or if worsening depression or psychosis occurs

            Anticholinergic effects including blurred vision, urinary retention, xerostomia, and constipation may occur

            Neuropsychiatric symptoms may occur unpredictably including anxiety and psychosis

            Bone fracture reported with use of antidepressant therapy; consider possibility of fracture if patient presents with unexplained bone pain, joint tenderness, bruising or swelling

            May cause orthostatic hypotension; use caution in patients at risk of this effect or that may not tolerate hypotensive episodes (eg, hypovolemia, cardiovascular or cerebrovascular disease and others)

            Sleep related activities including sleep driving, eating food, cooking, making phone calls reported; discontinue therapy if patient reports sleep-related episodes

            Possibility of EPS and neuroleptic malignant syndrome (NMS)

            May cause confusion in the elderly; avoid doses >6 mg/day


            Pregnancy & Lactation


            Available data from published epidemiologic studies and postmarketing reports have not established increased risk of major birth defects or miscarriage; there are risks of poor neonatal adaptation with exposure to drug during pregnancy

            Neonatal adverse effects

            • Neonates exposed to TCAs, including doxepin, late in third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding; such complications can arise immediately upon delivery
            • Reported clinical findings have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hyperreflexia, tremor, jitteriness, irritability and constant crying. These findings are consistent with either direct toxic effects of TCAs or possibly a drug discontinuation syndrome
            • Monitor neonates who were exposed to drug in third trimester of pregnancy for poor neonatal adaptation syndrome

            Animal data

            • Based on results from animal fertility studies conducted in rats, doxepin may reduce fertility in females and males of reproductive potential
            • In animal reproduction studies, oral administration of doxepin to rats and rabbits during period of organogenesis caused adverse developmental effects at doses 65 and 23 times maximum recommended human dose (MRHD) of 6 mg/day based on AUC, respectively
            • Oral administration to pregnant rats during pregnancy and lactation resulted in decreased pup survival and a delay in pup growth at doses 60 times MRHD based on AUC


            Data from published report presence of drug and metabolite in human milk; there are reports of excess sedation, respiratory depression, poor sucking and swallowing, and hypotonia in breastfed infants exposed to drug

            There are no data on effects of drug on milk production; because of potential for serious adverse reactions, including excess sedation and respiratory depression in a breastfed infant, advise patients that breastfeeding is not recommended during therapy

            Infants exposed to drug through breast milk should be monitored for excess sedation, respiratory depression and hypotonia

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Exact mechanism for doxepin's sleep maintenance effect is unknown; however, doxepin's action is believed to result from antagonism of the histamine H1 receptor

            Mechanism of action for depression is unknown; may increase CNS synaptic concentrations of serotonin and norepinephrine by inhibiting reuptake


            Peak plasma time: 2 hr

            Onset: >2 weeks (depression)


            Protein bound: 80%


            Hepatic CYP2D6, CYP2C19

            Metabolites: N-demethyldoxepin


            Half-life: 6-8 hr

            Excretion: Urine





            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.