PROCAINAMIDE HCL
Clinical safety rating
safeOther drugs that prolong the QT interval increase risk of torsades de pointes Can cause lupus-like syndrome and blood dyscrasias.
Other drugs that prolong the QT interval increase risk of torsades de pointes Can cause lupus-like syndrome and blood dyscrasias.
Treatment of documented ventricular arrhythmias (e.g., sustained ventricular tachycardia) that are life-threateningOff-label: Atrial fibrillation, atrial flutter, supraventricular tachycardia, Wolff-Parkinson-White syndrome
Lupus-like syndrome
Class Ia antiarrhythmic agent; blocks sodium channels, decreases phase 0 slope of action potential, prolongs refractory period, and increases action potential duration.
| Metabolism | Hepatic via N-acetyltransferase (NAT2) to N-acetylprocainamide (NAPA); also undergoes hydrolysis to p-aminobenzoic acid. |
| Excretion | Primarily renal (50-60% unchanged via glomerular filtration and tubular secretion) with 10-30% as N-acetylprocainamide (NAPA) metabolite; minor biliary/fecal (<5%). |
| Half-life | Terminal elimination half-life: 2.5-4.7 hours (3 hours typical) in normal renal function; prolonged to 11-20 hours in renal impairment; NAPA half-life 6-8 hours (prolonged in renal failure). |
| Protein binding | 15-25% bound primarily to alpha-1-acid glycoprotein and albumin. |
| Volume of Distribution | 1.5-2.5 L/kg (approximates total body water; indicates extensive tissue distribution). |
| Bioavailability | Oral: 75-95% (immediate-release); IM: 100%; IV: 100%. |
| Onset of Action | IV: 1-5 minutes; IM: 10-15 minutes; Oral: 30-60 minutes (immediate-release). |
| Duration of Action | IV/IM: 3-4 hours (antiarrhythmic effect); Oral immediate-release: 3-6 hours; extended-release: 8-12 hours (dosing interval). |
| Molecular Weight | 235.32 |
For life-threatening ventricular arrhythmias, IV: Loading dose: 100 mg administered at a rate of 25-50 mg/min, may repeat every 5 minutes until arrhythmia suppressed or up to a total of 500-1000 mg. Maintenance: IV infusion 1-4 mg/min. Oral: 250-500 mg every 3-6 hours; maximum 4 g/day.
| Dosage form | Injectable |
| Renal impairment | CrCl >50 mL/min: No adjustment. CrCl 10-50 mL/min: Administer every 6-12 hours. CrCl <10 mL/min: Administer every 12-24 hours. |
| Liver impairment | Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 25-50%. Child-Pugh Class C: Reduce dose by 50-75% or avoid use. |
| Pediatric use | IV: Loading dose: 15 mg/kg over 30-60 minutes, followed by maintenance infusion of 20-80 mcg/kg/min; maximum 2 g/day. Oral: 15-50 mg/kg/day in divided doses every 3-6 hours; maximum 4 g/day. |
| Geriatric use | Start at lower end of dosing range due to age-related decreased renal function and increased risk of hypotension and arrhythmias. Monitor renal function and adjust accordingly. |
| 1st trimester | Procainamide crosses the placenta. Limited human data; potential risk of neonatal lupus and heart block. Use only if clearly needed. |
| 2nd trimester | Similar considerations as t1. Monitor fetal heart rate for bradycardia. |
| 3rd trimester | May cause maternal hypotension and reduce uterine blood flow. Risk of neonatal bradycardia and QT prolongation. Avoid near term. |
Clinical note
Other drugs that prolong the QT interval increase risk of torsades de pointes Can cause lupus-like syndrome and blood dyscrasias.
| FDA category | Animal |
| Placental transfer | Crosses placenta extensively; achieves fetal serum concentrations approximately 60-70% of maternal levels. |
| Breastfeeding | Procainamide and its active metabolite NAPA are excreted into breast milk in low concentrations. Monitor infant for bradycardia, hypotension, and GI effects. Generally considered compatible with breastfeeding. |
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | FDA pregnancy category C. Procainamide crosses the placenta. In first trimester, risk of congenital anomalies is not well-studied; animal studies show no teratogenicity but use only if clearly needed. In second and third trimesters, chronic use may be associated with fetal bradycardia, QT prolongation, and neonatal lupus syndrome (transient). Avoid in pregnancy if possible. |
| Fetal Monitoring | Monitor maternal ECG (QTc interval), procainamide and NAPA serum concentrations, renal function, complete blood count (risk of agranulocytosis). Fetal monitoring: assess fetal heart rate and rhythm, consider fetal echocardiography for QT interval if maternal treatment prolonged. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies have not been conducted. Procainamide does not affect gonadotropin levels. Limited data; no specific fertility impairment reported. |
■ FDA Black Box Warning
Procanamide can cause agranulocytosis, leukopenia, and thrombocytopenia; fatal blood dyscrasias have occurred. Frequent blood counts are recommended.
| Common Effects | Lupus-like syndrome |
| Serious Effects |
Complete heart blockSecond-degree AV block (unless paced)Systemic lupus erythematosusKnown hypersensitivity to procainamide or ester-type anestheticsTorsade de pointesConcurrent use with other drugs that prolong QT interval
| Precautions | May cause lupus erythematosus-like syndrome (especially with slow acetylator phenotype); proarrhythmic effects (torsades de pointes); hypotension; bone marrow suppression; hepatotoxicity; potentiation of neuromuscular blocking agents. |
| Food/Dietary | No significant food interactions reported. However, changes in dietary salt intake may affect blood pressure control; avoid excessive caffeine or alcohol as they may trigger arrhythmias. Maintain consistent potassium and magnesium intake; severe electrolyte disbalances can alter drug effect. |
| Clinical Pearls | Procainamide HCL is a Class IA antiarrhythmic used for atrial and ventricular arrhythmias. It can cause lupus-like syndrome, especially in slow acetylators; monitor ANA titers. Renal dose adjustment is critical due to active metabolite N-acetylprocainamide (NAPA) accumulation. Watch for QT prolongation and torsades de pointes; avoid with other QT-prolonging drugs. Administer IV slowly to avoid hypotension; oral loading requires hepatic first-pass consideration. |
| Patient Advice | Take this medication exactly as prescribed; do not double doses if missed. · Report any symptoms of lupus (joint pain, rash, fever, chest pain) immediately. · Avoid sudden position changes to prevent dizziness from low blood pressure. · Tell your doctor all other medications, especially other heart rhythm drugs. · You may need regular blood tests to monitor drug levels and organ function. · Do not stop taking this medicine abruptly; sudden stop may worsen arrhythmia. · If using extended-release tablets, do not crush or chew them. |
Loading safety data…