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Quinidine

Prescription
Class IA Antiarrhythmic
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
2 available
Interactions
2 documented
Formulations
3

Mechanism of action

Natural cinchona alkaloid that blocks sodium channels (Class IA), prolongs action potential and refractory period, and has vagolytic (anticholinergic) properties. Also blocks potassium channels and alpha-adrenergic receptors (vasodilation).

At a glance

Class
Class IA Antiarrhythmic
Schedule
Prescription
Storage
Store at room temperature, protect from light

Dosing

🐕

Dog

Used for supraventricular arrhythmias (atrial fibrillation conversion) and ventr
Dose
6–16 mg/kg
Route
PO, IM
Frequency
q6–8h
🐈

Cat

Rarely used in cats
Dose
6–16 mg/kg
Route
PO, IM
Frequency
q8h

Formulations

💊

Other — 3

Strength
—
Strength
—
Strength
—

Storage

Store at room temperature, protect from light

Safety

Monitoring parameters

ECG (QT interval, QRS width)Serum quinidine levels (therapeutic 2–5 mcg/mL)Blood pressureGI tolerancePlatelet countDigoxin levels (quinidine doubles digoxin levels — reduce digoxin dose 50%)

Interactions

Major — 1

Digoxin
major
Quinidine reduces renal and non-renal digoxin clearance and displaces digoxin from tissue binding sites, increasing digoxin levels by ~100% (doubled).
Management: Reduce digoxin dose by 50% when adding quinidine. Monitor digoxin trough levels. Watch for digoxin toxicity (anorexia, arrhythmias).

Moderate — 1

Phenobarbital
moderate
Phenobarbital induces CYP3A4, increasing quinidine metabolism and reducing its antiarrhythmic efficacy.
Management: May need higher quinidine dose. Monitor quinidine levels and ECG response.

Brands

Other markets

Quinidex
Quinaglute

FAQs

Frequently asked questions

›What is Quinidine?
Quinidine is a class ia antiarrhythmic used in pets. Natural cinchona alkaloid that blocks sodium channels (Class IA), prolongs action potential and refractory period, and has vagolytic (anticholinergic) properties. Also blocks potassium channels and alpha-adrenergic receptors (vasodilation).
›What is Quinidine used for in pets?
Quinidine is used in veterinary medicine for: Used for supraventricular arrhythmias (atrial fibrillation conversion) and ventr; Rarely used in cats.
›What is the Quinidine dose for dogs?
For dogs, Quinidine is typically dosed as follows — Used for supraventricular arrhythmias (atrial fibrillation conversion) and ventr: 6–16 mg/kg PO/IM q6–8h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Quinidine dose for cats?
For cats, Quinidine is typically dosed as follows — Rarely used in cats: 6–16 mg/kg PO/IM q8h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›Does Quinidine need a prescription?
Yes. Quinidine is a prescription medication and should only be administered under veterinary supervision.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Related medicines

Other medicines in the same class (Class IA Antiarrhythmic).

Procainamide
Rx
Blocks sodium channels (Class IA), prolonging action potential duration and effective refractory period. Slows conduction velocity in atrial, ventricular, and accessory pathway tissue. Active metabolite N-acetylprocainamide (NAPA) has Class III (potassium channel) properties.
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