Home/Medicines/Mexiletine

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

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

Frequency

q8h

🐈

Cat

Feline ventricular arrhythmias are uncommon

Dose

—

Route

Frequency

N/A

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 — 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)

Educational reference only

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.

Educational reference only

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.

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