[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antiarrhythmics](https://durgical.com/en/pharmacology/classes/antiarrhythmics/) › Procainamide

# Procainamide

## Antiarrhythmics?

Antiarrhythmics

## High alert?

An error with this medicine can cause serious harm: double checks and protocols are used.

A class IA antiarrhythmic given intravenously for ventricular tachycardia. Long use can cause a lupus-like syndrome and serious blood disorders.

Updated Nov 1, 2026

## Quick facts

**Group**
[Antiarrhythmics](https://durgical.com/en/pharmacology/classes/antiarrhythmics/)

**Target**
Cardiac sodium channel Nav1.5 (and potassium channels, through its metabolite NAPA)

**Key effects**
Hypotension with intravenous use · Nausea

**Monitor**
Continuous ECG · Blood pressure · Kidney function

**ATC**
C01BA02

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Clinical What the labels mean

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

Procainamide blocks sodium channels (slower conduction, wider QRS) and lengthens repolarisation (longer QT): a class IA profile. Its liver metabolite N-acetylprocainamide (NAPA) blocks potassium channels and adds a class III effect. It is a peripheral vasodilator and can lower blood pressure when given quickly.

- Procainamide blocks sodium channels: slower conduction, wider QRS
- Repolarisation lengthens (longer QT), with help from its metabolite NAPA
- Re-entry in atria and ventricles is suppressed

## Indications

- Documented life-threatening ventricular arrhythmias such as sustained ventricular tachycardia [Ventricular tachycardia →](https://durgical.com/en/conditions/ventricular-tachycardia/)

## Adverse effects

### Common

- Hypotension with intravenous use
- Nausea, vomiting and diarrhoea
- Positive antinuclear antibodies (ANA)
- Rash and fever

### Serious (rare, important)

- Drug-induced lupus (arthralgia, pleuritis, pericarditis, fever)
- Agranulocytosis, bone marrow depression and thrombocytopenia, sometimes fatal
- QT prolongation with torsades de pointes
- Asystole or ventricular fibrillation, more often intravenously

## Contraindications

- Complete heart block (risk of asystole)
- Systemic lupus erythematosus
- Torsades de pointes
- Hypersensitivity to procainamide
- Caution in myasthenia gravis, which it can worsen

## Key interactions

**Other class IA drugs (quinidine, disopyramide)**
More conduction slowing, depressed contractility and hypotension

**Other QT-prolonging drugs**
Higher risk of torsades de pointes

**Succinylcholine and other neuromuscular blockers**
Procainamide reduces acetylcholine release, so smaller doses of the blocker may be needed

## What is monitored

- Continuous ECG: QRS width and QT
- Blood pressure, lying down, during the infusion
- Complete blood count and ANA with long-term use
- Kidney function; procainamide and NAPA levels where available

## Administration and safety

- Given by slow intravenous injection or infusion with a pump, the patient lying down, with ECG and blood pressure monitoring.
- The infusion is stopped if hypotension or marked QRS widening appears, as the protocol states.
- A slightly yellow solution may be used; one darker than light amber is discarded.

## Pregnancy and breastfeeding

Human data are lacking; it is used in pregnancy only if clearly needed. It passes into breast milk.

## Nursing care

- Keep the patient supine and record blood pressure frequently during the infusion.
- Watch the monitor for QRS widening, QT prolongation and new arrhythmias.
- Ask about joint pain, chest pain on breathing, fever, sore throat or bruising during longer courses.

## Pharmacokinetics

**Metabolism**
Partly acetylated in the liver to NAPA; fast acetylators make more NAPA than slow acetylators

**Elimination**
Kidneys (procainamide and NAPA); both accumulate in kidney failure and in older people

**Onset and duration**
Fast intravenously; intramuscular peaks within an hour

## Memory aid

ProcainAMIDE makes ANA: lupus-like syndrome, low white cells, and a long QT to watch.

## Test yourself

Think of the answer, then tap the question to see it.

## Which autoimmune syndrome is classic with long-term procainamide?

Drug-induced lupus with positive ANA (arthralgia, serositis, fever), more frequent in slow acetylators.

## What is NAPA and why does it matter?

N-acetylprocainamide, the active metabolite; it blocks potassium channels, prolongs the QT and accumulates in kidney failure.

## Why is the blood count checked during procainamide treatment?

It can cause agranulocytosis and bone marrow depression, sometimes fatal.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/procainamide/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## What the labels mean

**High alert**
An error with this medicine can cause serious harm: double checks and protocols are used.

## Connections

## Related drugs 3

- [Lidocaine](https://durgical.com/en/pharmacology/lidocaine/)
- [Amiodarone](https://durgical.com/en/pharmacology/amiodarone/)
- [Quinidine](https://durgical.com/en/pharmacology/quinidine/)

## Related conditions 1

- [Ventricular tachycardia](https://durgical.com/en/conditions/ventricular-tachycardia/)

[← Back to the class: Antiarrhythmics](https://durgical.com/en/pharmacology/classes/antiarrhythmics/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - PROCAINAMIDE HYDROCHLORIDE injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=17e47845-daad-434c-a784-6d3875b0d704) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C01BA02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/procainamide/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/procainamide/