Verapamil
Also known as: Calan, Isoptin, Verelan, Covera-HS, Securon
Verapamil is a medication used primarily to correct abnormally fast heart rhythms. * **Compliance is Key:** To be effective, your pet must receive all doses exactly as prescribed by your veterinarian. Do not skip doses or stop the medication abruptly. * **What to Watch For:** Contact your veterinarian immediately if your pet becomes unusually lethargic, shows exercise intolerance, begins wheezing, has shortness of breath or a cough, or develops any sudden change in behavior or attitude. * **Dietary Notes:** Follow your veterinarian's instructions regarding giving this medication with or without food, as food can affect how certain formulations are absorbed.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Supraventricular tachycardia
- Supraventricular tachyarrhythmias
- Supraventricular tachyarrhythmias (Acute)
- To control ventricular rate in atrial fibrillation
- Cardiovascular disease
- Cardiovascular disease
- Supraventricular tachycardia
- Treatment of hypertension
- Emergency treatment for hemodynamically unstable and sustained (continuous) supraventricular tachycardia
- General arrhythmias
- Acute termination of supraventricular tachycardia
- Supraventricular tachyarrhythmias
- Supraventricular tachyarrhythmias (Acute)
How it is given
Possible side effects
- Hypotension
- Bradycardia
- Tachycardia
- Exacerbation of congestive heart failure (CHF)
- Peripheral edema
- AV block
- Pulmonary edema
- Nausea
- Constipation
- Dizziness
- Headache
- Fatigue
- Precipitation or exacerbation of congestive heart failure
Cautions & contraindications
- Cardiogenic shock
- Severe CHF (unless secondary to a supraventricular tachycardia amenable to verapamil)
- Hypotension (<90 mmHg systolic)
- Sick sinus syndrome
- 2nd or 3rd degree AV block
- Digoxin intoxication
- Hypersensitivity to verapamil
- Recent use (within a few hours) of IV beta-adrenergic blockers
- Hypotension
- Left ventricular dysfunction
- Heart failure
- > **Critical Warning:** IV verapamil is contraindicated within a few hours of IV beta-adrenergic blocking agents (e.g., propranolol). The combination can severely depress myocardial contractility and AV node conduction, potentially causing rapid hemodynamic deterioration and ventricular fibrillation. * **Cardiac Disease:** Use with caution in patients with heart failure or hypertrophic cardiomyopathy (HCM) due to negative inotropic effects. * **Organ Impairment:** Toxicity may be potentiated in patients with hepatic or renal impairment. * **Arrhythmias:** Use very cautiously in patients with atrial fibrillation and Wolff-Parkinson-White (WPW) syndrome as fatal arrhythmias may result. * **Endocrine:** May increase blood glucose in dogs; use with caution in diabetic animals. * **Breed Sensitivities:** Verapamil is a neurotoxic substrate of P-glycoprotein. Use with extreme caution in herding breeds (e.g., Collies, Australian Shepherds) that may possess the MDR1 (ABCB1) gene mutation causing a nonfunctional P-gp protein.
Drug interactions
- ACE Inhibitors: May cause additive hypotensive effects
- Alpha-Adrenergic Blockers (e.g., prazosin): May cause additive hypotensive effects
- Beta-Adrenergic Blockers (e.g., propranolol): May cause additive negative cardiac inotrope and chronotrope effects; IV combination is contraindicated
- Doxorubicin: Verapamil may increase doxorubicin concentrations
- COPP Chemotherapy: May decrease oral absorption of verapamil
- Cyclosporine: Verapamil may increase cyclosporine levels
- Dantrolene: Cardiovascular collapse reported in animals when used with verapamil
- Digoxin: Verapamil may increase blood levels of digoxin; monitoring recommended
- Disopyramide: May cause additive effects and impair left ventricular function; concurrent use within 24-48 hours not recommended
- Diuretics: May cause additive hypotensive effects
- Erythromycin, Clarithromycin: May increase verapamil levels
Frequently asked questions
What is Verapamil used for in pets?
Verapamil is a medication used primarily to correct abnormally fast heart rhythms. * **Compliance is Key:** To be effective, your pet must receive all doses exactly as prescribed by your veterinarian. Do not skip doses or stop the medication abruptly. * **What to Watch For:** Contact your veterinarian immediately if your pet becomes unusually lethargic, shows exercise intolerance, begins wheezing, has shortness of breath or a cough, or develops any sudden change in behavior or attitude. * **Dietary Notes:** Follow your veterinarian's instructions regarding giving this medication with or without food, as food can affect how certain formulations are absorbed.
Is Verapamil safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
Worried about your pet?
Peqaboo’s AI helps you track symptoms, understand lab reports, and know when to see a vet.
Get the Peqaboo app