What Is Procainamide? Uses, Dosage, and What You Need to Know in 2026

Procainamide is a prescription antiarrhythmic medication with over 70 years of use in cardiology. It belongs to the Class IA category of antiarrhythmic drugs and is used to treat life-threatening heart rhythm disorders. Here's a complete patient guide to understanding procainamide—what it is, what it treats, how it's given, and what you need to know before and during treatment.

What Is Procainamide?

Procainamide (generic name: procainamide hydrochloride; brand names: Pronestyl, Procanbid—both discontinued) is a Class IA antiarrhythmic drug. It was first approved by the FDA in 1950 and launched by Bristol-Myers Squibb under the brand name Pronestyl in 1951. Today it's available only in generic injectable form, as the commercial oral formulations were discontinued.

Procainamide is classified as a sodium channel blocker. It belongs to the same drug class as quinidine—the "prototype" Class IA antiarrhythmic. Procainamide has similar cardiac effects to quinidine but with weaker vagal blocking activity and less effect on cardiac contractility, making it somewhat better tolerated in certain patients.

What Is Procainamide Used For?

Procainamide is FDA-approved for treating the following heart rhythm disorders:

Sustained ventricular tachycardia (VT): A life-threatening fast heart rhythm originating in the lower chambers of the heart

Supraventricular tachycardias (SVTs): Fast heart rhythms originating above the ventricles, including atrioventricular nodal reentrant tachycardia (AVNRT) and others

Atrial flutter and atrial fibrillation (AFib): Irregular rhythms originating in the upper chambers (atria)

Wolff-Parkinson-White (WPW) syndrome: A congenital electrical abnormality with an accessory conduction pathway; procainamide is particularly useful for acute termination in WPW-related tachycardia

Off-label uses include malignant hyperthermia (a rare emergency reaction to certain anesthetics) and post-operative junctional ectopic tachycardia in pediatric cardiac surgery patients.

How Is Procainamide Given?

Procainamide is administered by injection only (commercially). It can be given:

Intravenously (IV): The most common route for acute arrhythmia management. IV infusion produces therapeutic drug levels within minutes. Loading dose is typically 100–200 mg every 5 minutes (not to exceed 50 mg/min) up to 1 g total, followed by a maintenance infusion of 2–6 mg/min.

Intramuscularly (IM): Peak plasma levels are reached in 15–60 minutes after IM injection.

FDA guidelines require that procainamide therapy be initiated in a hospital setting with continuous ECG and blood pressure monitoring. It cannot be started at home or in an outpatient clinic.

Compounded oral procainamide (capsules or suspension) is also available from specialty compounding pharmacies for patients requiring long-term oral maintenance therapy—since the commercial tablet formulation was discontinued.

Procainamide Dosage: What to Expect

Dosing is individualized based on arrhythmia type, body weight, kidney function, and response to treatment. Key dosage parameters:

Adult IV loading dose: 100–200 mg IV over 5 min, repeated every 5 min as needed; maximum 1 g; rate must not exceed 50 mg/min

Adult IV maintenance: 2–6 mg/min by continuous infusion

Renal adjustment: Dose must be reduced in patients with impaired kidney function; the drug is primarily renally eliminated with a half-life of 3–4 hours in normal renal function

Therapeutic drug levels: Monitoring of procainamide and its active metabolite N-acetylprocainamide (NAPA) guides dosing; levels >12 mg/L may indicate toxicity

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Who Should NOT Take Procainamide?

Procainamide is contraindicated (not safe to use) in patients with:

Complete AV block or 2nd/3rd degree heart block (without a functioning pacemaker)

Systemic lupus erythematosus (SLE) — procainamide can worsen lupus

Torsades de pointes (a specific type of dangerous arrhythmia)

Hypersensitivity to procainamide or related ingredients

Myasthenia gravis (procainamide can worsen muscle weakness)

Is Procainamide Hard to Find?

Yes—procainamide can be challenging to find at retail pharmacies because it's primarily distributed through hospital supply chains. medfinder can call pharmacies in your area to find which ones have it in stock. For more information on why it's hard to find and what to do, read our guide on why procainamide is hard to find.