Procainamide
PRONESTYL
What it isClass IA sodium channel blocker; ventricular arrhythmia and pre-excited atrial fibrillation.
Why this oneIt is the 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.
FDA-approved for
- arrhythmias (~1950)
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
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
⚠ BOXED WARNINGS
- Blood dyscrasias including agranulocytosis
- Positive ANA and lupus-like syndrome
- Increased mortality in asymptomatic PVCs
Classes and tags
Clinical profile
Active metabolites
Mechanism of action: Procainamide ballicule
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