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Mexiletine

Prescription
Class IB Antiarrhythmic (Sodium Channel Blocker)
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
1 available
Interactions
2 documented
Formulations
1

Mechanism of action

Blocks voltage-gated sodium channels in cardiac tissue (same class as lidocaine), shortening action potential duration and effective refractory period. Used for ventricular arrhythmias. Oral analog of lidocaine with good bioavailability.

At a glance

Class
Class IB Antiarrhythmic (Sodium Channel Blocker)
Schedule
Prescription
Storage
Store at room temperature below 30°C

Dosing

🐕

Dog

Oral alternative to IV lidocaine for chronic ventricular arrhythmia management (
Dose
4–8 mg/kg
Route
PO
Frequency
q8h
🐈

Cat

Feline ventricular arrhythmias are uncommon
Dose
—
Route
PO
Frequency
N/A

Formulations

💊

Other — 1

Strength
—

Storage

Store at room temperature below 30°C

Safety

Monitoring parameters

ECG (Holter monitoring for VPC burden)Heart rateGI toleranceNeurological signs (tremors, ataxia — toxicity)

Interactions

Moderate — 2

Sotalol
moderate
Mexiletine (Class IB — shortens APD) + sotalol (Class III — prolongs APD): pharmacologically complementary combination used intentionally for refractory ventricular arrhythmias.
Management: Recognized therapeutic combination for refractory VT in dogs (Boxers with ARVC). Start both at low doses. Monitor ECG and Holter.
Lidocaine
moderate
Both are Class IB sodium channel blockers. Additive sodium channel blockade may cause excessive cardiac depression.
Management: Usually not combined — mexiletine is oral replacement for lidocaine CRI. When transitioning, overlap briefly and monitor ECG.

Brands

Other markets

Mexitil

FAQs

Frequently asked questions

›What is Mexiletine?
Mexiletine is a class ib antiarrhythmic (sodium channel blocker) used in pets. Blocks voltage-gated sodium channels in cardiac tissue (same class as lidocaine), shortening action potential duration and effective refractory period. Used for ventricular arrhythmias. Oral analog of lidocaine with good bioavailability.
›What is Mexiletine used for in pets?
Mexiletine is used in veterinary medicine for: Oral alternative to IV lidocaine for chronic ventricular arrhythmia management (; Feline ventricular arrhythmias are uncommon.
›What is the Mexiletine dose for dogs?
For dogs, Mexiletine is typically dosed as follows — Oral alternative to IV lidocaine for chronic ventricular arrhythmia management (: 4–8 mg/kg PO q8h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Mexiletine dose for cats?
For cats, Mexiletine is typically dosed as follows — Feline ventricular arrhythmias are uncommon: undefined undefined PO N/A. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›Does Mexiletine need a prescription?
Yes. Mexiletine 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 →