Nortriptyline Equivalent to Amitriptyline 10mg
The equivalent dosage of nortriptyline to amitriptyline 10mg is approximately 8.25mg, based on the evidence-based dose equivalence ratio. 1
Dose Equivalence Calculation
- According to comprehensive research on antidepressant dose equivalents, amitriptyline 122.3mg is equivalent to fluoxetine 40mg, while nortriptyline 100.9mg is also equivalent to fluoxetine 40mg 1
- Using these ratios, we can calculate that nortriptyline is approximately 1.21 times more potent than amitriptyline (122.3/100.9 = 1.21) 1
- Therefore, 10mg of amitriptyline would be equivalent to approximately 8.25mg of nortriptyline (10mg ÷ 1.21) 1
Clinical Considerations
- Nortriptyline is typically started at 10-25mg at bedtime and can be increased to 25-100mg as tolerated for pain management and depression 2
- For pain management specifically, nortriptyline is often preferred over amitriptyline due to its superior side effect profile while maintaining similar efficacy 2
- In clinical practice, since nortriptyline is typically available in 10mg, 25mg, and 50mg capsules, the closest practical equivalent to amitriptyline 10mg would be nortriptyline 10mg 2
Side Effect Profiles
- Nortriptyline generally has a better side effect profile than amitriptyline, particularly with regards to sedation and anticholinergic effects 2
- Amitriptyline is specifically listed among sedating antidepressants by the American Academy of Sleep Medicine, while nortriptyline is not highlighted for this purpose 2
- Both medications can affect cardiac conduction and should be used with caution in patients with cardiac conditions 2
Therapeutic Plasma Levels
- For optimal clinical effect, plasma levels of amitriptyline plus nortriptyline should be between 60-220 ng/ml, and nortriptyline alone between 60-140 ng/ml 3
- Nortriptyline has a narrower therapeutic window compared to amitriptyline, which may require more careful dose titration 3
Dosing Recommendations
- When switching from amitriptyline to nortriptyline, start with the equivalent dose (approximately 10mg of nortriptyline for 10mg of amitriptyline) 2, 1
- For elderly patients, who are more sensitive to the sedative effects of both drugs, lower starting doses are recommended 2
- Dose adjustments should be made gradually (every 3-7 days) to minimize side effects 2
Common Pitfalls and Caveats
- Despite the calculated equivalence, individual patient response may vary due to differences in metabolism and drug sensitivity 3
- The ratio of amitriptyline to nortriptyline in plasma can vary significantly between patients, affecting clinical response 3
- Both medications can increase heart rate, with higher plasma levels correlating with greater increases in heart rate 4
- For pain management, both medications are often effective at doses lower than those required for depression treatment 2