Home/Medicines/Verapamil

Verapamil

Prescription

Class IV Antiarrhythmic / Non-Dihydropyridine Calcium Channel Blocker

Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

2 available

Interactions

6 documented

Formulations

Mechanism of action

Blocks L-type voltage-gated calcium channels in cardiac and smooth muscle. In the heart: slows SA and AV node conduction, reduces contractility, and prolongs AV nodal refractory period. In vasculature: causes coronary and peripheral vasodilation.

At a glance

Class

Class IV Antiarrhythmic / Non-Dihydropyridine Calcium Channel Blocker

Schedule

Prescription

Storage

Store at room temperature, protect from light and moisture

Dosing

🐕

Dog

Used for supraventricular tachycardia (SVT), atrial fibrillation rate control

Dose

0.05–0.15 mg/kg

Route

IV, PO

Frequency

q8h (PO); as needed (IV)

🐈

Cat

Used for feline hypertrophic cardiomyopathy (rate control, diastolic relaxation)

Dose

0.5–1 mg/kg

Route

IV, PO

Frequency

q8h (PO)

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 and moisture

Safety

Monitoring parameters

ECG (AV conduction)Blood pressureHeart rateCardiac function (echocardiogram)

Educational reference only

Interactions

Contraindicated — 4

Propranolol

contraindicated

IV verapamil + IV beta-blocker: synergistic negative inotropy, chronotropy, and dromotropy causing severe bradycardia, AV block, hypotension, or asystole.

Management: NEVER give IV verapamil and IV beta-blocker together. Oral combination used very cautiously only under cardiologist supervision.

Carvedilol

contraindicated

Non-selective beta-blocker + non-DHP calcium channel blocker: synergistic negative inotropy causing severe bradycardia, AV block, or cardiac arrest.

Management: NEVER combine, especially IV. Oral combination only under specialist supervision.

Esmolol

contraindicated

IV beta-blocker + IV non-DHP calcium channel blocker: synergistic negative inotropy, chronotropy, dromotropy causing asystole or cardiac arrest.

Management: NEVER give IV esmolol and IV verapamil. Wait adequate time between if sequential use needed.

Metoprolol

contraindicated

IV beta-blocker + IV verapamil: risk of asystole. Even oral combination requires extreme caution.

Management: NEVER give IV simultaneously. Oral combination very rarely justified.

Major — 1

Dantrolene

major

Both have negative inotropic effects. Dantrolene reduces intracellular calcium release; verapamil blocks calcium channels. Combined: hyperkalemia and cardiovascular collapse documented.

Management: Avoid combination. If dantrolene needed for malignant hyperthermia in patient on verapamil, prepare for aggressive cardiovascular support.

Moderate — 1

Digoxin

moderate

Verapamil increases digoxin levels by 50-75% via P-glycoprotein inhibition and reduced renal clearance.

Management: Reduce digoxin dose by 33-50% when adding verapamil. Monitor digoxin levels.

Educational reference only

Brands

Other markets

Calan

Isoptin

FAQs

Frequently asked questions

›What is Verapamil?

Verapamil is a class iv antiarrhythmic / non-dihydropyridine calcium channel blocker used in pets. Blocks L-type voltage-gated calcium channels in cardiac and smooth muscle. In the heart: slows SA and AV node conduction, reduces contractility, and prolongs AV nodal refractory period. In vasculature: causes coronary and peripheral vasodilation.

›What is Verapamil used for in pets?

Verapamil is used in veterinary medicine for: Used for supraventricular tachycardia (SVT), atrial fibrillation rate control; Used for feline hypertrophic cardiomyopathy (rate control, diastolic relaxation).

›What is the Verapamil dose for dogs?

For dogs, Verapamil is typically dosed as follows — Used for supraventricular tachycardia (SVT), atrial fibrillation rate control: 0.05–0.15 mg/kg IV/PO q8h (PO); as needed (IV). Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Verapamil dose for cats?

For cats, Verapamil is typically dosed as follows — Used for feline hypertrophic cardiomyopathy (rate control, diastolic relaxation): 0.5–1 mg/kg IV/PO q8h (PO). Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›Does Verapamil need a prescription?

Yes. Verapamil 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