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Diltiazem

Prescription

Calcium channel blocker (benzothiazepine)

Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

3 available

Interactions

8 documented

Formulations

Mechanism of action

Blocks L-type calcium channels in cardiac and smooth muscle cells, reducing heart rate, decreasing myocardial oxygen demand, and promoting coronary vasodilation

At a glance

Class

Calcium channel blocker (benzothiazepine)

Schedule

Prescription

Storage

Store below 25°C, protect from light

Dosing

🐕

Dog

Supraventricular tachycardia / Atrial fibrillation

Dose

0.5–2 mg/kg

Route

Frequency

TID

Max dose

120 mg/dose; 360 mg/day

Duration: Long-term or until arrhythmia controlled

Supraventricular tachycardia (acute IV)

Dose

0.1–0.25 mg/kg

Route

Frequency

Once, may repeat in 15 min

Max dose

15 mg/dose; 30 mg/day

Duration: Single administration

🐈

Cat

Hypertrophic cardiomyopathy

Dose

1.5–3.5 mg/kg

Route

Frequency

TID

Max dose

15 mg/dose; 45 mg/day

Duration: Long-term

Formulations

💊

Tablet — 3

Strength

30mg

Available in India

Strength

60mg

Available in India

Strength

90mg

Available in India

💉

Injection — 1

Strength

5mg/mL

Available in India

Storage

Store below 25°C, protect from light

Safety

Absolute contraindications — do not use

Severe hypotension
Sick sinus syndrome without pacemaker

Use with caution

Concurrent beta-blockers
Risk of severe bradycardia and AV block

Adverse effects

Common

Bradycardia

Anorexia

Lethargy

Serious

AV block

Severe hypotension

Heart failure worsening

Monitoring parameters

Heart rateECGBlood pressureHepatic enzymes

Interactions

Major — 7

Digoxin

major

Diltiazem increases digoxin serum levels by 20-35% and both have additive AV nodal depression

Management: Reduce digoxin dose by 25-50% when adding diltiazem. Monitor digoxin levels and ECG.

Atenolol

major

Both suppress AV conduction and myocardial contractility; combined use risks severe bradycardia and heart block

Management: Use combination with extreme caution. Monitor ECG. May be intentional for rate control in refractory cases.

Propranolol

major

Additive negative chronotropy and dromotropy: risk of severe bradycardia, AV block, and cardiac arrest.

Management: Use with extreme caution under cardiologist supervision. Do not give both IV. Monitor ECG continuously if combined.

Amiodarone

major

Amiodarone + diltiazem: additive negative chronotropic and dromotropic effects. Risk of severe bradycardia and AV block.

Management: Avoid combination. If used, continuous ECG monitoring essential.

Carvedilol

major

Non-selective beta-blocker + non-DHP calcium channel blocker: additive negative inotropy, chronotropy, dromotropy. Risk of severe bradycardia and heart failure decompensation.

Management: Avoid concurrent use or use under cardiologist supervision with ECG monitoring.

Esmolol

major

Additive AV nodal depression and negative inotropy. Risk of severe bradycardia and heart failure.

Management: Avoid concurrent IV use. If both needed for SVT, use under cardiologist supervision with continuous ECG and have pacing available.

Metoprolol

major

Beta-blocker + non-DHP calcium channel blocker: additive negative chronotropy and dromotropy. Risk of severe bradycardia and AV block.

Management: Avoid concurrent use or use under cardiologist supervision with ECG monitoring.

Moderate — 1

Pimobendan

moderate

Diltiazem is a negative inotrope (calcium channel blocker) that may partially oppose pimobendan's positive inotropy. However, commonly combined in practice for DCM + atrial fibrillation.

Management: Used together clinically under cardiologist supervision. Monitor echocardiographic response.

Brands

India

Dilzem

Sun Pharma

DTZ

Cipla

International

Cardizem

Bausch Health

FAQs

Frequently asked questions

›What is Diltiazem?

Diltiazem is a calcium channel blocker (benzothiazepine) used in pets. Blocks L-type calcium channels in cardiac and smooth muscle cells, reducing heart rate, decreasing myocardial oxygen demand, and promoting coronary vasodilation

›What is Diltiazem used for in pets?

Diltiazem is used in veterinary medicine for: Supraventricular tachycardia / Atrial fibrillation; Supraventricular tachycardia (acute IV); Hypertrophic cardiomyopathy.

›What is the Diltiazem dose for dogs?

For dogs, Diltiazem is typically dosed as follows — Supraventricular tachycardia / Atrial fibrillation: 0.5–2 mg/kg PO TID; Supraventricular tachycardia (acute IV): 0.1–0.25 mg/kg IV Once, may repeat in 15 min. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Diltiazem dose for cats?

For cats, Diltiazem is typically dosed as follows — Hypertrophic cardiomyopathy: 1.5–3.5 mg/kg PO TID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What are the side effects of Diltiazem?

Common: Bradycardia, Anorexia, Lethargy. Serious (call your vet immediately): AV block, Severe hypotension, Heart failure worsening.

›Does Diltiazem need a prescription?

Yes. Diltiazem is a prescription medication and should only be administered under veterinary supervision.

›When should Diltiazem not be used?

Do not use Diltiazem if: Severe hypotension; Sick sinus syndrome without pacemaker.

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 →