Nortriptyline Dosing
Start nortriptyline at 10-25 mg nightly and titrate by 25 mg every 3-7 days to a target range of 50-150 mg nightly, with therapeutic plasma levels of 50-150 ng/mL. 1, 2, 3
Starting Dose
The initial dose should be 10-25 mg at bedtime 1, 2. This low starting dose minimizes anticholinergic side effects (dry mouth, sedation, urinary hesitancy) while allowing assessment of individual tolerance. The FDA label confirms this approach, recommending initiation at low levels with gradual increases 3.
Titration Schedule
Increase by 25 mg every 3-7 days as tolerated 2. This gradual escalation allows you to identify the minimum effective dose while monitoring for side effects. The 2010 Mayo Clinic guidelines specifically recommend this titration interval for secondary-amine tricyclics like nortriptyline 2.
Target Dose Range
The therapeutic target is 50-150 mg nightly 1. Multiple NCCN cancer pain guidelines consistently cite this range for neuropathic pain management 1. The FDA label states that doses above 100 mg daily require plasma level monitoring, and doses exceeding 150 mg daily are not recommended 3.
Therapeutic Plasma Levels
Maintain plasma concentrations between 50-150 ng/mL 2, 4, 3. This therapeutic window is well-established with Level 1 evidence 4. The 2002 AGNP-TDM guidelines specifically define the nortriptyline therapeutic range as 70-170 ng/mL, though most sources converge on 50-150 ng/mL 5, 4. Plasma levels above 150 ng/mL increase anticholinergic side effects without additional benefit 3, 6.
Special Populations
Elderly Patients
For elderly or medically frail patients, use slower titration and consider starting at the lower end (10 mg nightly) 1. The FDA label recommends 30-50 mg daily in divided doses for elderly patients 3. Research in frail elderly (mean age 84) showed that an average dose of 80 mg/day achieves plasma levels of 100 ng/mL, though individual requirements vary 20-fold 7. A 2002 guideline for Alzheimer's patients recommends starting at 10 mg at bedtime with a maximum of 40 mg per day given twice daily 5.
Dose Prediction
A single 50 mg test dose with plasma level measurement at 24 hours can predict steady-state requirements and identify slow metabolizers early 7, 8. This approach is particularly useful in elderly patients to prevent toxic accumulation.
Clinical Monitoring
- Onset of analgesic effect: Typically earlier than antidepressant effect, often within 1-3 weeks 1
- Adequate trial duration: 6-8 weeks with at least 2 weeks at maximum tolerated dose 2
- Plasma level monitoring: Recommended when doses exceed 100 mg daily 3
- Steady state: Achieved between 1-3 weeks 6
Key Advantages Over Tertiary Amines
Nortriptyline (a secondary amine) is better tolerated than amitriptyline or imipramine (tertiary amines), with fewer anticholinergic side effects, though tertiary amines may be slightly more efficacious 1. This makes nortriptyline the preferred first-line tricyclic for most patients.
Common Pitfalls
- Avoid rapid titration: This increases anticholinergic side effects and orthostatic hypotension
- Don't exceed 150 mg daily: Higher doses increase toxicity risk without additional benefit 3
- Monitor for cardiotoxicity: Though less common with nortriptyline than other tricyclics, ECG monitoring is prudent, especially in elderly patients 6
- Individual variability: Dose requirements can vary 20-fold between patients due to CYP2D6 polymorphisms 7, 9