Procainamide (Pronestyl, Procanbid)

Anesthesia Implications

Updated On: July 23, 2026

Classification:

Class Ia antiarrhythmic (sodium-channel blocker)

Therapeutic Effects:

Antiarrhythmic, terminates and controls ventricular and supraventricular arrhythmias including stable wide-complex tachycardia and pre-excited atrial fibrillation

Time to Onset:

During loading infusion

Time to Peak Effects:

End of load

Duration:

3-4 hours (parent drug); longer via NAPA

Primary Considerations:

Infusion discipline - Load slowly (up to 50 mg/min, or 15 mg/kg over 30-60 min); STOP for hypotension, QRS widening >50% of baseline, arrhythmia termination, or reaching the max dose. Continuous ECG and blood-pressure monitoring are mandatory.

Proarrhythmia - Class Ia agents prolong QT and can precipitate torsades; avoid stacking with other QT-prolonging drugs (ondansetron, droperidol, volatile agents, methadone).

Myocardial depression/hypotension - Negative inotropy and vasodilation; have vasopressors and fluids ready, and use cautiously in heart failure.

Active metabolite - N-acetylprocainamide (NAPA) has Class III activity and accumulates in renal impairment, extending QT effects.

Drug Interactions - Additive QT prolongation with other antiarrhythmics and antiemetics; potentiates non-depolarizing NMB; cimetidine and amiodarone raise levels.

Pediatric Implications - Weight-based (15 mg/kg load over 30-60 min); used for SVT and stable VT in PALS, with the same hemodynamic and QRS/QT monitoring.

Obstetric Implications - Category C; crosses the placenta. Considered relatively safe for maternal arrhythmias in pregnancy when needed. Present in breast milk in small amounts.

Contraindications:

Absolute:

Complete heart block

Torsades de pointes / significant QT prolongation

Systemic lupus erythematosus

Relative:

Second-degree AV block without pacing

Severe heart failure

Caution:

Renal/hepatic impairment

Myasthenia gravis

Concurrent QT-prolonging drugs

IV push dose:

Loading: 15 mg/kg IV over 30-60 min (or up to 50 mg/min) until arrhythmia resolves, hypotension, QRS widens >50%, or max dose (adult); 15 mg/kg over 30-60 min (pediatric).

IV infusion dose:

1-4 mg/min IV infusion after loading; reduce in renal impairment (NAPA accumulation).

Method of Action:

Blocks fast sodium channels, slowing phase 0 depolarization and conduction; prolongs action-potential duration and refractoriness. Its metabolite NAPA blocks potassium channels (Class III effect).

Metabolism:

Hepatic (acetylation to active NAPA)

Elimination:

Renal

Additional Notes:

Continuous ECG and blood-pressure monitoring required during loading. Keep resuscitation drugs and defibrillator available.

Master Anesthesia

Master Anesthesia

Procainamide (Pronestyl, Procanbid)

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