Procainamide

PRONESTYL

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Pronunciation: proe-kayn-A-mide

Procainamide ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Procainamide ballicule

Procainamide PRONESTYL mascot mnemonic cartoon — Visual mnemonic: Procainamide mascot
**“(QT) Pro(longing) cane, honestly”**

What it isClass IA sodium channel blocker; ventricular arrhythmia and pre-excited atrial fibrillation.

Why this oneThe preferred agent in pre-excited atrial fibrillation, where AV nodal blockers are dangerous.

What limits itDrug-induced lupus in a third on long-term therapy, and agranulocytosis. NAPA metabolite accumulates in renal failure; QT prolongation.

Procainamide molecular structure (skeletal formula) — Molecular structure: Procainamide

Procainamide prescription history

Animated chart of estimated U.S. prescriptions per year, Antiarrhythmics (class I/III) (1930–2026). Procainamide enters in 1951 (estimated).

FDA-approved for

arrhythmias (~1950)

Classes and tags

Clinical profile

Therapeutic safety burden4 / 4

Overdose danger4 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades4 / 4

Direct muscarinic antagonism0 / 4

Defining liabilityProarrhythmia, hypotension and potentially fatal blood dyscrasias

FDA label

Read the full label on DailyMed ↗

BOXED WARNING Prolonged use often produces positive ANA and a lupus erythematosus-like syndrome; risk of blood dyscrasias (agranulocytosis, bone marrow depression); reserve for life-threatening ventricular arrhythmias.

FDA dosing	Population	Start	Target	Max
Ventricular arrhythmias (IM)	Adult	50 mg/kg/day in divided doses q3-6h	per response/levels	per response
Ventricular arrhythmias (IV)	Adult	IV load slowly, rate not to exceed 50 mg/min, under ECG monitoring	per response	per response
Arrhythmias with anesthesia/surgery (IM)	Adult	100-500 mg IM

Renal Reduce dose/frequency in renal impairment (adjust for age and renal function)

Hepatic Undefined

IV administration rate not to exceed 50 mg/min

Instructions

IV: dilute and give slowly, not exceeding 50 mg/min, with ECG and blood pressure monitoring
Switch to oral procainamide for long-term maintenance

Available strengths

inj 100, 500 mg/mL

Contraindications

Complete heart block
Second-degree AV block or hemiblock (unless ventricular rate controlled by pacemaker)
Established systemic lupus erythematosus
Torsades de pointes (Group 1A antiarrhythmics contraindicated)

Cautions

Lupus-like syndrome with prolonged use
Blood dyscrasias — agranulocytosis, neutropenia, thrombocytopenia
Hypotension and proarrhythmia, especially with IV use
QT prolongation / torsades
Hepatotoxicity (elevated LFTs, rare liver failure)

Adverse reactions

Hypotension, ventricular asystole/fibrillation (IV)
Lupus erythematosus-like syndrome
Agranulocytosis, neutropenia, hemolytic anemia
GI: anorexia, nausea, vomiting, diarrhea, bitter taste
Dizziness, weakness, depression, psychosis
Elevated liver enzymes

Pregnancy Undefined

Lactation Undefined

Cost

Procainamide (PRONESTYL)

Strength		#/mo	generic $/unit	CostPlus
100 mg/mL	inj	per unit		not offered
500 mg/mL	inj	per unit		not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Procainamide is administered under clinical supervision and dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

Active metabolites

NAPA

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Memory aids: interaction avatars

OCT2/MATE1 substrate

weak base

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Self-check

Procainamide: In which AF setting are AV nodal blockers dangerous and it is preferred?
Pre-excited AF.
Procainamide: Which metabolite accumulates in renal failure?
NAPA.