PRONESTYL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for PRONESTYL (PRONESTYL).

How it works

Class IA antiarrhythmic; blocks sodium channels, decreases phase 0 upstroke velocity, prolongs action potential duration, and increases effective refractory period.

What the body does with it

Metabolism	Primarily hepatic via N-acetyltransferase (NAT2); active metabolite N-acetylprocainamide (NAPA) is renally excreted.
Excretion	Renal excretion accounts for approximately 50-60% of procainamide elimination as unchanged drug, with an additional 10-30% as the active metabolite N-acetylprocainamide (NAPA). Biliary/fecal excretion is minimal (<5%).
Half-life	3-5 hours in patients with normal renal function; prolonged to 10-20 hours in renal impairment. Clinical context: Requires dosing every 3-4 hours to maintain therapeutic levels; sustained-release formulations allow Q6-8h dosing.
Protein binding	Approximately 15-20%, primarily to albumin. Minimal binding reduces risk of drug interactions.
Volume of Distribution	2-3 L/kg, indicating extensive tissue distribution (e.g., heart, liver, kidneys). Clinical meaning: Loading doses are required to rapidly achieve therapeutic concentrations.
Bioavailability	Oral: 70-85% (immediate release); Sustained release: ~80% with food increasing absorption. IV: 100%.
Onset of Action	IV: 5-10 minutes; IM: 10-30 minutes; Oral: 30-60 minutes.
Duration of Action	IV/IM: 3-4 hours; Oral immediate release: 3-4 hours; Sustained release: 6-8 hours. Note: Action duration dependent on renal function and cardiac output.

Classification & Brands

Dosing & administration

For life-threatening ventricular arrhythmias: loading dose of 100 mg IV over 5 minutes, repeated every 5 minutes as needed up to a total of 1 g. Maintenance: continuous IV infusion of 1-4 mg/min. Oral: 50 mg/kg/day in divided doses every 3-6 hours.

Dosage form	CAPSULE
Renal impairment	For CrCl 10-50 mL/min: administer every 6-12 hours. For CrCl <10 mL/min: administer every 12-24 hours.
Liver impairment	Child-Pugh Class A: reduce dose by 25%. Child-Pugh Class B: reduce dose by 50%. Child-Pugh Class C: avoid use or reduce dose by 75%.
Pediatric use	IV: 3-6 mg/kg over 5 minutes, not to exceed 100 mg, repeat every 5-10 minutes up to a total of 15 mg/kg. Oral: 15-50 mg/kg/day in divided doses every 3-6 hours.
Geriatric use	Initiate at lower doses and titrate slowly due to increased risk of hypotension and cardiac toxicity. Monitor renal function and adjust dosing interval based on CrCl.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for PRONESTYL (PRONESTYL).

Breastfeeding	Procainamide and its active metabolite NAPA are excreted into breast milk with M/P ratio approximately 1.0 and 0.55, respectively. Limited data suggest low risk in infants; monitor for bradycardia, gastrointestinal effects, and drug accumulation. Use caution, especially in premature or neonatal infants with impaired renal function.
Teratogenic Risk	First trimester: No well-controlled studies; limited data suggest low risk of congenital anomalies. Second and third trimesters: Associated with fetal bradycardia, QT prolongation, and neonatal arrhythmias; use only if clearly needed considering risk-benefit.

Warnings & precautions

■ FDA Black Box Warning

May cause agranulocytosis; fatal blood dyscrasias have occurred. Regular blood counts are recommended.

Side Effect Profile

Serious Effects

Absolute Contraindications

Complete heart block, second-degree AV block (unless pacemaker), torsade de pointes, hypersensitivity to procainamide or related drugs, systemic lupus erythematosus.

Clinical Precautions

Precautions

Lupus-like syndrome (especially in slow acetylators), QT prolongation and torsade de pointes, proarrhythmic effects, hypotension, myocardial depression, caution in renal/hepatic impairment.

Clinical Tips & Counseling

Drug interactions

Loading safety data…

PRONESTYL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for PRONESTYL (PRONESTYL).

How it works

Class IA antiarrhythmic; blocks sodium channels, decreases phase 0 upstroke velocity, prolongs action potential duration, and increases effective refractory period.

What the body does with it

Metabolism	Primarily hepatic via N-acetyltransferase (NAT2); active metabolite N-acetylprocainamide (NAPA) is renally excreted.
Excretion	Renal excretion accounts for approximately 50-60% of procainamide elimination as unchanged drug, with an additional 10-30% as the active metabolite N-acetylprocainamide (NAPA). Biliary/fecal excretion is minimal (<5%).
Half-life	3-5 hours in patients with normal renal function; prolonged to 10-20 hours in renal impairment. Clinical context: Requires dosing every 3-4 hours to maintain therapeutic levels; sustained-release formulations allow Q6-8h dosing.
Protein binding	Approximately 15-20%, primarily to albumin. Minimal binding reduces risk of drug interactions.
Volume of Distribution	2-3 L/kg, indicating extensive tissue distribution (e.g., heart, liver, kidneys). Clinical meaning: Loading doses are required to rapidly achieve therapeutic concentrations.
Bioavailability	Oral: 70-85% (immediate release); Sustained release: ~80% with food increasing absorption. IV: 100%.
Onset of Action	IV: 5-10 minutes; IM: 10-30 minutes; Oral: 30-60 minutes.
Duration of Action	IV/IM: 3-4 hours; Oral immediate release: 3-4 hours; Sustained release: 6-8 hours. Note: Action duration dependent on renal function and cardiac output.

Classification & Brands

Dosing & administration

Dosage form	CAPSULE
Renal impairment	For CrCl 10-50 mL/min: administer every 6-12 hours. For CrCl <10 mL/min: administer every 12-24 hours.
Liver impairment	Child-Pugh Class A: reduce dose by 25%. Child-Pugh Class B: reduce dose by 50%. Child-Pugh Class C: avoid use or reduce dose by 75%.
Pediatric use	IV: 3-6 mg/kg over 5 minutes, not to exceed 100 mg, repeat every 5-10 minutes up to a total of 15 mg/kg. Oral: 15-50 mg/kg/day in divided doses every 3-6 hours.
Geriatric use	Initiate at lower doses and titrate slowly due to increased risk of hypotension and cardiac toxicity. Monitor renal function and adjust dosing interval based on CrCl.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for PRONESTYL (PRONESTYL).

Breastfeeding	Procainamide and its active metabolite NAPA are excreted into breast milk with M/P ratio approximately 1.0 and 0.55, respectively. Limited data suggest low risk in infants; monitor for bradycardia, gastrointestinal effects, and drug accumulation. Use caution, especially in premature or neonatal infants with impaired renal function.
Teratogenic Risk	First trimester: No well-controlled studies; limited data suggest low risk of congenital anomalies. Second and third trimesters: Associated with fetal bradycardia, QT prolongation, and neonatal arrhythmias; use only if clearly needed considering risk-benefit.

Warnings & precautions

■ FDA Black Box Warning

May cause agranulocytosis; fatal blood dyscrasias have occurred. Regular blood counts are recommended.

Side Effect Profile

Serious Effects

Absolute Contraindications

Complete heart block, second-degree AV block (unless pacemaker), torsade de pointes, hypersensitivity to procainamide or related drugs, systemic lupus erythematosus.

Clinical Precautions

Precautions

Lupus-like syndrome (especially in slow acetylators), QT prolongation and torsade de pointes, proarrhythmic effects, hypotension, myocardial depression, caution in renal/hepatic impairment.

Clinical Tips & Counseling

Drug interactions

Loading safety data…