What the FDA labels say about taking them together
Nortriptyline and quinidine
Nortriptyline's FDA label of December 4, 2024 names quinidine in its drug interactions section; the quinidine label PlainMeds reads does not name nortriptyline.
Check it at the source: the nortriptyline FDA label on DailyMed (effective December 4, 2024); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the nortriptyline label say about quinidine?
Nortriptyline label, drug interactionsThe drugs that inhibit cytochrome P450 2D6 include some that are not metabolized by the enzyme (quinidine; cimetidine) and many that are substrates for P450 2D6 (many other antidepressants, phenothiazines, and the Type 1C antiarrhythmics propafenone and flecainide).
Nortriptyline label, warningsThe concomitant administration of quinidine and nortriptyline may result in a significantly longer plasma half-life, higher AUC, and lower clearance of nortriptyline.
Source: FDA drug label (PAMELOR), SpecGx LLC, effective December 4, 2024 (SPL set e17dc299-f52d-414d-ab6e-e809bd6f8acb), via openFDA; the full label on DailyMed
What does the quinidine label say about nortriptyline?
Quinidine's label (effective February 1, 2018) does not name nortriptyline in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Quinidine Gluconate), Sun Pharmaceutical Industries, Inc., effective February 1, 2018 (SPL set 5023f053-fcc4-4c2c-aa59-9ec198ad185e), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Nortriptyline | Quinidine | |
|---|---|---|
| Labeled for | Depression | Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.113 per capsule 10 mg capsule | $4.92 per tablet 324 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once