What the FDA labels say about taking them together
Atazanavir and quinidine
Atazanavir's FDA label of August 6, 2025 names quinidine in its contraindications section; the quinidine label PlainMeds reads does not name atazanavir. The atazanavir label: “Concomitant use of REYATAZ with ritonavir and either quinidine or amiodarone is contraindicated due to the potential for serious or life-threatening reactions such as cardiac arrhythmias. …”
Check it at the source: the atazanavir FDA label on DailyMed (effective August 6, 2025, Aurobindo Pharma Limited); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the atazanavir label say about quinidine?
Atazanavir label, contraindicationsDrug Class: Antiarrhythmics; Drugs within class that are contraindicated with atazanavir capsules: Amiodarone (with ritonavir), quinidine (with ritonavir)
Atazanavir label, drug interactionsConcomitant Drug Class/Specific Drugs: Antiarrhythmics: amiodarone, quinidine amiodarone, bepridil, lidocaine (systemic), quinidine; Effect on Concentration of Atazanavir or Concomitant Drug: ↑ amiodarone, bepridil, lidocaine (systemic), quinidine; Clinical Comment: Concomitant use of atazanavir with ritonavir and either quinidine or amiodarone is contraindicated due to the potential for serious or life-threatening reactions such as cardiac arrhythmias [see ]. Coadministration with atazanavir without ritonavir has the potential to produce serious and/or life-threatening adverse events but has not been studied. …
Source: FDA drug label (Reyataz, NDA021567), E.R. Squibb & Sons, L.L.C., effective December 5, 2024 (SPL set 165cff62-b284-4a27-a65d-9ec8a5bfcdd8), via openFDA
Source: FDA drug label (Atazanavir Sulfate), Aurobindo Pharma Limited, effective August 6, 2025 (SPL set 7fbea274-d6b5-4faa-bbf0-05fefab42114), via openFDA; the full label on DailyMed
What does the quinidine label say about atazanavir?
Quinidine's label (effective February 1, 2018) does not name atazanavir 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
| Atazanavir | Quinidine | |
|---|---|---|
| Labeled for | HIV | Atrial fibrillation |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $2.23 per capsule 300 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