Yes — the active ingredient is metabolized by a gene known to vary between individuals.
Relevant genes: CYP2D6
Gene2Rx covers this medication using the same CPIC and FDA guidelines GeneSight uses, costs $5-$49 instead of several hundred, and works with your existing 23andMe data.
Pamelor is affected by pharmacogenetics through the CYP2D6 gene. Your genotype for this gene can change how your body processes Pamelor, which can affect both how well it works and how well you tolerate it. The strongest evidence level on this page is Strong, based on CPIC or FDA guidelines.
Published guidance from CPIC on how nortriptyline should be dosed or substituted based on your CYP2D6 phenotype.
| Phenotype | What it means | Recommendation | Evidence |
|---|---|---|---|
|
Ultrarapid Metabolizer
CYP2D6
|
Your body breaks down nortriptyline much faster than normal, which means the drug may not reach effective levels. A different antidepressant or a higher dose may be needed. |
CPIC
Avoid tricyclic use due to potential lack of efficacy. Consider alternative drug not metabolized by CYP2D6.
If a TCA is warranted, consider titrating to a higher target dose (compared to normal metabolizers). Utilize therapeutic drug monitoring to guide dose adjustments.
|
Strong |
|
Normal Metabolizer
CYP2D6
|
Your body processes nortriptyline at a normal rate. The standard dose should work as expected for you. |
CPIC
Initiate therapy with recommended starting dose.
|
Strong |
|
Intermediate Metabolizer
CYP2D6
|
Your body breaks down nortriptyline more slowly than normal, which can lead to higher drug levels and a greater chance of side effects. A lower dose may be recommended. |
CPIC
Consider 25% reduction of recommended starting dose.g Utilize therapeutic drug monitoring to guide dose adjustments.
|
Moderate |
|
Poor Metabolizer
CYP2D6
|
Your body breaks down nortriptyline very slowly, causing the drug to build up to high levels and significantly increasing the risk of side effects. A different antidepressant is recommended. |
CPIC
Avoid tricyclic use due to potential for side effects. Consider alternative drug not metabolized by CYP2D6.
If a TCA is warranted, consider 50% reduction of recommended starting dose.g Utilize therapeutic drug monitoring to guide dose adjustments.
|
Strong |
|
Indeterminate
CYP2D6
|
The impact of your genotype on response to this drug is unknown |
CPIC
Initiate therapy with recommended starting dose.
|
— |
|
Not available
CYP2D6
|
The impact of your genotype on response to this drug is unknown |
CPIC
Initiate therapy with recommended starting dose.
|
— |
Source: CPIC
CYP2D6 is the most clinically important pharmacogene. It metabolizes around a quarter of all prescription drugs, including many antidepressants, opioids, and stimulants. The gene is unusually variable: roughly 7 percent of people are poor metabolizers (they barely activate CYP2D6), and another 1 to 3 percent are ultrarapid metabolizers (their enzyme is overactive).
For most CYP2D6 drugs, poor metabolizers feel stronger effects and more side effects at standard doses, while ultrarapid metabolizers may feel almost nothing. For prodrugs like codeine, the relationship flips: poor metabolizers feel less effect because they can't activate the drug.
Browse the full drug-class: Tricyclic antidepressants.
This page describes the general pharmacogenetics. A Gene2Rx report analyzes your own DNA to tell you which metabolizer group you fall into, across every medication.
Get your report Look up another medicationInformational only — not medical advice. Pharmacogenetic guidance describes population-level patterns; your individual response depends on many factors. Never start, stop, or change a medication without talking to your prescribing clinician.