Home/Medicines/Quinidine

Quinidine

Prescription

Class IA Antiarrhythmic

Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

2 available

Interactions

2 documented

Formulations

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

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 →

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%)

Educational reference only

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.

Educational reference only

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.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database

Related medicines

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

Procainamide

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.

dogcat