Procainamide
Procainamide hydrochloride
Also known as: Pronestyl · Procanbid · Biocoryl · novocainamidum · procainamidi chloridum · procainamidi hydrochloridum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Ventricular tachyarrhythmias | 2-4 mg/kg IV slowly (over two minutes) up to a total dose of 12-20 mg/kg until arrhythmia controlled and then a CRI may be started at 10-40 micrograms/kg/minute | IV | Intermittent boluses then CRI | — | 🌎 NA |
| Ventricular tachyarrhythmias | 20-30 mg/kg PO q6-8h | PO | q6-8h | — | 🌎 NA |
| Acute management of SVTs | 6-8 mg/kg IV over 3 minutes or 6-20 mg/kg IM | IV/IM | Once | — | 🌎 NA |
| Chronic management of SVTs | 10-20 mg/kg PO q6-8h | PO | q6-8h | — | 🌎 NA |
| Acute treatment of ventricular tachycardia | 10-15 mg/kg IV bolus over 1-2 minutes; if continued parenteral administration required may use a constant rate IV infusion at 25-50 micrograms/kg/minute | IV | Bolus then CRI | — | 🌎 NA |
| Chronic treatment of ventricular tachycardia | 10-20 mg/kg PO q6h | PO | q6h | — | 🌎 NA |
| Ventricular tachycardia | 6.6-8.8 mg/kg slowly IV over 5 minutes, then give as a CRI at 40-100 micrograms/kg/minute | IV | Bolus then CRI | — | 🌎 NA |
| Chronic treatment of ventricular arrhythmias | 20-23 mg/kg PO q8h | PO | q8h | — | 🌎 NA |
| Arrhythmias (using sustained-release tablets) | 20 mg/kg PO q8h | PO | q8h | — | 🌎 NA |
| Arrhythmias (intravenous therapy) | 6-8 mg/kg IV bolus, 20-40 micrograms/kg/min CRI | IV | Bolus then CRI | — | 🌎 NA |
| Acute treatment of atrial fibrillation | 5-15 mg/kg IV slowly to effect | IV | To effect | — | 🌎 NA |
| Ventricular tachycardia (if lidocaine ineffective) | 20-50 micrograms/kg/min IV or 6-15 mg/kg IM q4-6h | IV/IM | CRI or q4-6h | — | 🌎 NA |
- Ventricular tachyarrhythmias: Previous recommendations of 8-20 mg/kg PO q6-8h are almost certainly too low
- Acute management of SVTs: After drugs have been used to slow AV nodal conduction (i.e., diltiazem)
- Chronic management of SVTs: Higher dosages of up to 40 mg/kg q6h have been necessary to treat junctional SVTs in some dogs
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Chronic management of SVTs | 3-8 mg/kg PO q6-8h | PO | q6-8h | — | 🌎 NA |
| Chronic management of SVTs | 1-2 mg/kg slowly IV; 10-20 micrograms/kg/minute constant rate IV infusion | IV | Bolus then CRI | — | 🌎 NA |
| Chronic management of SVTs | 7.5-20 mg/kg q 6-8h | PO | q6-8h | — | 🌎 NA |
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Atrial fibrillation / Ventricular tachycardia | 1 mg/kg/min IV, not too exceed 20 mg/kg (20 minutes) total dose | IV | Once | 20 minutes max | 🌎 NA |
| Atrial fibrillation / Ventricular tachycardia | 25-35 mg/kg PO q8h | PO | q8h | — | 🌎 NA |
| V-Tach | 1 mg/kg/minute IV up to a total dose of 20 mg/kg; or 25-35 mg/kg PO q8h | IV/PO | Once or q8h | — | 🌎 NA |
- Atrial fibrillation / Ventricular tachycardia: Not as effective as quinidine for atrial fibrillation
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Procainamide is a Class 1A antiarrhythmic agent structurally related to the local anesthetic procaine. It is primarily used in veterinary medicine to manage ventricular tachyarrhythmias (such as ventricular premature complexes [VPCs] and ventricular tachycardia) and certain supraventricular tachycardias (SVTs).
Because of its broad spectrum of activity for both atrial and ventricular arrhythmias, it is often considered an ideal first-line IV therapeutic agent when a wide QRS complex tachycardia cannot be definitively identified as supraventricular or ventricular in origin.
Clinical Pearl: Unlike humans, dogs are poor acetylators and do not form appreciable amounts of the active metabolite N-acetyl-procainamide (NAPA). Therefore, therapeutic monitoring in dogs should focus solely on procainamide levels.
Mechanism of action
Procainamide acts primarily as a fast sodium channel blocker (Class 1A), similar to quinidine.
- Phase 0 Blockade: Slows the influx of sodium during Phase 0 depolarization of the cardiac action potential.
- → Prolongs the refractory period in both the atria and ventricles.
- → Decreases myocardial excitability and depresses automaticity and conduction velocity.
- Anticholinergic Effects: Exhibits mild vagolytic properties which may cause slight increases in heart rate or unpredictable rate changes.
- ECG Effects: Commonly causes widening of the QRS complex and prolongation of the PR and QT intervals.
Safety & warnings
Contraindications
- Myasthenia gravis
- Hypersensitivity to procainamide, procaine, or chemically related drugs
- Systemic lupus erythematosus (SLE) in humans (unknown in dogs)
- Torsade de pointes
- 2nd or 3rd degree heart block (unless artificially paced)
- Doberman pinschers and boxers with dilated cardiomyopathy (relative - proarrhythmic risk)
- Dogs with subaortic stenosis (relative - proarrhythmic risk)
Adverse effects
- Anorexia
- Vomiting
- Diarrhea
- Weakness
- Hypotension (especially with rapid IV injection)
- Negative inotropism
- Widened QRS complex
- Prolonged QT interval
- AV block
- Multiform ventricular tachycardias
- Fevers
- Leukopenias
Precautions
Use with extreme caution in patients with cardiac glycoside intoxication. Use with caution in patients with significant hepatic or renal disease, or congestive heart failure (CHF). Dosages should usually be reduced in patients with renal failure, CHF, or those who are critically ill.
Warning: Profound hypotension can occur if injected too rapidly IV. Do not use in Doberman pinschers and boxers with dilated cardiomyopathy or dogs with subaortic stenosis as it may be proarrhythmic and induce sudden death.
Drug interactions
May increase procainamide levels; procainamide dose may need to be reduced
Procainamide may antagonize effects in patients with myasthenia gravis
May increase procainamide levels
Procainamide may enhance hypotensive effects
Toxic effects may be additive, and cardiac effects unpredictable
Procainamide may potentiate or prolong the neuromuscular blocking activity
Toxic effects may be additive, and cardiac effects unpredictable
Toxic effects may be additive, and cardiac effects unpredictable
Toxic effects may be additive, and cardiac effects unpredictable
May increase procainamide levels
May increase procainamide levels
Monitoring
- ECG (continuously with IV dosing)
- Blood pressure (during IV administration)
- Clinical signs of toxicity (GI signs, weakness)
- Serum drug levels (Trough levels for oral therapy. Note: Request lab to not run NAPA for dogs. Target range: 3-8 to 8-20 mcg/mL in dogs; 4-10 mcg/mL in horses)
Pharmacokinetics
Half-life
Absorption
Onset of action is practically immediate after IM or IV administration. Oral bioavailability in dogs is approximately 85% with an absorption half-life of 0.5 hours, though highly variable. Food, delayed gastric emptying, or decreased stomach pH may delay oral absorption.
Distribution
Highest distribution into the CSF, liver, spleen, kidneys, lungs, heart, and muscles. Volume of distribution in dogs is approximately 1.4-3 L/kg. Protein binding is low (approximately 15% in dogs). Crosses the placenta and is excreted into milk.
Metabolism
In humans, metabolized to the active metabolite N-acetyl-procainamide (NAPA). Dogs, however, do not form appreciable amounts of NAPA as they are unable to appreciably acetylate aromatic and hydrazine amino groups.
Elimination
In dogs, approximately 90% (50-70% unchanged) of an intravenous dose is excreted in the urine as procainamide and metabolites within 24 hours.
Overdose
Clinical signs of overdosage can include hypotension, lethargy, confusion, nausea, vomiting, and oliguria. Cardiac signs may include widening of the QRS complex, junctional tachycardia, ventricular fibrillation, or intraventricular conduction delays.
- Oral Ingestion: Emptying of the gut and charcoal administration may be beneficial to remove unabsorbed drug.
- Hypotension: IV fluids, plus dopamine, phenylephrine, or norepinephrine could be considered.
- Cardiotoxicity: A 1/6 molar intravenous infusion of sodium lactate may be used in an attempt to reduce cardiotoxic effects.
- Elimination: Forced diuresis using fluids and diuretics along with reduction of urinary pH can enhance renal excretion.
- AV Block: Temporary cardiac pacing may be necessary should severe AV block occur.
Available products
Formulations
- Injection solution
- Oral capsules
- Extended-release oral tablets
Human-labeled
- Procainamide HCl Injection Solution: 100 mg/mL in 10 mL multi-dose vials and 500 mg/mL in 2 mL vials
- Procainamide HCl Oral Capsules: 250 mg & 375 mg
- Procainamide HCl Extended-Release Oral Tablets: 250 mg, 500 mg, & 1000 mg (Note: Not recommended for initial therapy in veterinary medicine)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at room temperature. Refrigeration may retard the development of oxidation, but the solution may be stored at room temperature. The solution may be used if the color is no darker than a light amber.
Client information
- Administration: Oral products should be administered at evenly spaced intervals throughout the day and night to maintain steady blood levels.
- Feeding: Unless otherwise directed by your veterinarian, give the medication on an empty stomach (at least 1 hour before feeding).
- Monitoring: Notify your veterinarian immediately if your pet's condition deteriorates or if you notice signs of toxicity such as vomiting, diarrhea, severe lethargy, or weakness.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.