What the FDA labels say about taking them together
Quinidine and tetrabenazine
Tetrabenazine's FDA label of November 29, 2019 names quinidine in its drug interactions section; the quinidine label PlainMeds reads does not name tetrabenazine. The tetrabenazine label: “Strong CYP2D6 inhibitors markedly increase exposure to these metabolites.”
Check it at the source: the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.); the tetrabenazine FDA label on DailyMed (effective November 29, 2019, Oceanside Pharmaceuticals).
What does the quinidine label say about tetrabenazine?
Quinidine's label (effective February 1, 2018) does not name tetrabenazine 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
What does the tetrabenazine label say about quinidine?
Tetrabenazine label, drug interactionsStrong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine, quinidine) markedly increase exposure to these metabolites.
Tetrabenazine label, warnings and precautionsThe use of tetrabenazine tablets should be avoided in combination with other drugs that are known to prolong QTc, including antipsychotic medications (e.g., chlorpromazine, haloperidol, thioridazine, ziprasidone), antibiotics (e.g., moxifloxacin), Class 1A (e.g., quinidine, procainamide) and Class III (e.g., amiodarone, sotalol) antiarrhythmic medications or any other medications known to prolong the QTc interval [see Drug Interactions ( 7.5 )].
Source: FDA drug label (tetrabenazine), NDA021894 (Bausch), as published by Oceanside Pharmaceuticals, effective November 29, 2019 (SPL set 5867189c-17bd-4e70-a079-c4730f9950d1), 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
| Quinidine | Tetrabenazine | |
|---|---|---|
| Labeled for | Atrial fibrillation | n/a |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $4.92 per tablet 324 mg tablet | $0.702 per tablet 12.5 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