Doxepin Dosing and Usage
For depression and anxiety, start doxepin at 75 mg daily and titrate to an optimal range of 75-150 mg/day, with a maximum of 300 mg/day for severe illness; for sedation purposes in conditions like chronic hives, doses as low as 25-50 mg/day may suffice. 1
Standard Dosing for Depression and Anxiety
- Initial dose: 75 mg/day for patients with mild to moderate depression 1
- Optimal therapeutic range: 75-150 mg/day for most patients 1
- Severe illness: May require gradual titration up to 300 mg/day, though additional benefit beyond this dose is rarely obtained 1
- Mild symptoms or emotional symptoms accompanying organic disease: 25-50 mg/day may be sufficient 1
Dosing Schedule Options
- Divided dosing: Total daily dose can be split throughout the day 1
- Once-daily dosing: Maximum 150 mg/day when given as a single dose at bedtime 1
- Important: The 150 mg capsule strength is for maintenance therapy only and should not be used to initiate treatment 1
Therapeutic Drug Monitoring
- Therapeutic plasma concentration range: 50-250 ng/mL (doxepin plus desmethyldoxepin metabolite) 2
- Clinical context matters: Lower plasma levels may be sufficient when doxepin is used primarily for sedation rather than antidepressant effects 2
- Monitoring level: Level 3 recommendation (useful for therapeutic drug monitoring) 2
Time to Therapeutic Effect
- Anti-anxiety effect: Appears before the antidepressant effect 1
- Optimal antidepressant effect: May not be evident for 2-3 weeks 1
- Adequate trial duration: Requires at least 4-8 weeks, with dosage increases every 5-7 days until therapeutic benefits or significant side effects appear 2
Special Populations
Elderly Patients
- Start low: Begin at the low end of the dosing range due to increased risk of decreased hepatic, renal, or cardiac function 1
- Monitor closely: Sedating drugs may cause confusion and oversedation in elderly patients 1
Long-term Maintenance
- Duration: Continue treatment for 4-9 months after satisfactory response for first episode of major depression 2
- Recurrent depression: Longer duration may be beneficial for patients with 2 or more episodes 2
- Reassessment: After 9 months, consider dosage reduction to reassess need for continued medication 2
Discontinuation
- Taper gradually: Discontinue over 10-14 days to limit withdrawal symptoms 2
- Withdrawal symptoms possible: Not indicative of addiction, but gradual withdrawal prevents these symptoms 1
Key Safety Considerations
Cardiovascular Monitoring
- Cardiac toxicity risk: Obtain screening ECG for patients over 40 years old 2
- Caution in cardiac disease: Use with caution in patients with ischemic cardiac disease or ventricular conduction abnormalities 2
Common Adverse Effects
- Most common: Drowsiness, which tends to disappear with continued therapy 1
- Anticholinergic effects: Dry mouth, blurred vision, constipation, urinary retention 1
- Cardiovascular: Hypotension, hypertension, tachycardia reported occasionally 1
Overdose Risk
- Potentially fatal: Deaths have been reported with doxepin overdose 1
- Critical manifestations: Cardiac dysrhythmias, severe hypotension, convulsions, CNS depression including coma 1
Clinical Advantages
- Dual benefit: Effective for both depression and anxiety, with anxiolytic effects appearing before antidepressant effects 1, 3
- Long-term safety: Demonstrated feasibility, efficacy, and safety in 5-15 year studies of chronic depression 4
- Drug interactions: Minimal adverse interactions with prescription and non-prescription drugs 4
- Comorbid conditions: High degree of safety in patients with concomitant cardiovascular and other physical disorders 4