Procainamide

Pronunciation: proe-kane-AH-mide.

Generic name
procainamide hydrochloride
Drug class
Class Ia antiarrhythmic (sodium channel blocker)
Form
Injection (IM/IV); extended-release oral tablets (Canada, maintenance therapy only)
Route
Intramuscular or intravenous injection (United States); intravenous injection and oral extended-release maintenance tablets have historically been available in Canada
Legal status
Prescription-only, hospital/specialist-administered in the markets where it remains available

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada

Australia: · Full directory

What procainamide hydrochloride is and how it works

Procainamide is a Class Ia antiarrhythmic medicine used, in a hospital or closely monitored setting, to treat serious, life-threatening irregular heart rhythms (arrhythmias), particularly sustained ventricular tachycardia. It works by slowing electrical conduction in the heart. (1)

Procainamide carries a genuine, serious boxed warning: prolonged use often leads to a positive antinuclear antibody (ANA) blood test, with or without a lupus-like illness (joint pain, fever, skin changes, chest-wall pain). It also carries a real, separate risk of serious blood-cell problems, including agranulocytosis (a severe drop in a type of white blood cell that fights infection), which is why regular blood tests are part of safe treatment, especially in the first 3 months.

Mechanism of action: how procainamide hydrochloride works

Procainamide is a Class Ia antiarrhythmic that blocks fast sodium channels, slowing conduction velocity and prolonging the effective refractory period and action potential duration in atrial and ventricular tissue. Its active metabolite, N-acetylprocainamide (NAPA), has additional Class III antiarrhythmic activity. (1) (2)

What procainamide hydrochloride is used for

Life-threatening ventricular arrhythmias

Used to treat documented life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia, always started and monitored in a hospital setting. No antiarrhythmic drug, including procainamide, has been shown to improve survival in people without symptoms from their arrhythmia. (1) (2)

Other symptomatic arrhythmias (Canada)

Also used for other symptomatic ventricular arrhythmias where the severity warrants intervention, atrial fibrillation of recent onset, and paroxysmal atrial tachycardia that has not responded to other measures. (2)

Before taking procainamide hydrochloride

Do not take / not appropriate for

  • Do not receive procainamide if you have complete heart block, or second- or third-degree AV block without a pacemaker. (all countries) (1) (2)
  • Do not receive procainamide if you have systemic lupus erythematosus (SLE). (all countries) (1) (2)
  • Do not receive procainamide if you have torsades de pointes or a known allergy to procainamide or related medicines such as procaine. (all countries) (1) (2)
  • Do not receive procainamide if you have suspected myasthenia gravis, without your specialist's specific assessment. (Canada) (2)

Tell your clinician about

  • Any history of lupus or a positive ANA test.
  • Any history of blood disorders, including low white blood cell counts.
  • Kidney or liver problems, since these change how procainamide is cleared from the body.
  • All other medicines, especially other antiarrhythmics, anticholinergic drugs, neuromuscular blockers, and certain antibiotics (kanamycin, neomycin, streptomycin).
  • Whether you are pregnant, plan to become pregnant, or are breastfeeding.
(1) (2)

How to take procainamide hydrochloride

  • Procainamide is given by injection (into a muscle or a vein) by a healthcare professional in a hospital or closely monitored clinical setting -- it is not a medicine you take on your own at home.
  • Continuous ECG (heart rhythm) and blood pressure monitoring are used throughout intravenous administration.
  • Where oral extended-release tablets are used (Canada), they are for maintenance therapy only, after your heart rhythm has already been stabilised on injectable or standard-release procainamide, and must be swallowed whole -- never crushed or chewed.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5)

Missed dose

Since procainamide is given and monitored by a healthcare team (by injection, or as hospital-initiated extended-release tablets), any question about a missed or delayed dose should be directed to your treating clinician or care team, not managed on your own.

Overdose

An overdose of procainamide is a medical emergency that can cause severe low blood pressure, dangerous heart rhythm changes (including ventricular fibrillation and QRS widening), confusion, nausea, and vomiting. It is treated in hospital with supportive care, medicines to raise blood pressure, and, when needed, hemodialysis, which significantly reduces procainamide levels; seek emergency medical care immediately if an overdose is suspected. (2)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Nausea, vomiting, loss of appetite (more common with oral forms, in about 3-4% of users).

What to notice: Nausea, vomiting, loss of appetite (more common with oral forms, in about 3-4% of users).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Dizziness.

What to notice: Dizziness.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

A positive ANA blood test (without necessarily having lupus-like symptoms).

What to notice: A positive ANA blood test (without necessarily having lupus-like symptoms).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Drug fever.

What to notice: Drug fever.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Bitter taste.

What to notice: Bitter taste.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Serious warnings

Signs of a lupus-like syndrome — boxed_warning

Symptoms: Joint pain, unexplained fever, skin changes or rash, or chest-wall (pleuritic) pain.

Action: Contact your clinician promptly for assessment and an ANA blood test -- procainamide can cause a positive ANA test with or without a lupus-like illness, especially with prolonged use, and your clinician will decide whether to continue, adjust, or stop treatment. (1) (2)

Signs of a serious blood disorder (agranulocytosis/bone marrow depression) — serious

Symptoms: Fever, chills, sore throat, unusual bruising or bleeding, or signs of infection.

Action: Seek medical attention immediately and have blood counts checked right away -- agranulocytosis and other serious blood disorders occur in approximately 0.5% of people receiving procainamide, most often in the first 12 weeks of treatment, and have been fatal in 20-25% of reported agranulocytosis cases. This is why regular blood counts (weekly for the first 3 months, then periodically) are part of safe treatment. (1) (2)

Signs of low blood pressure during intravenous treatment — serious

Symptoms: Lightheadedness, fainting, or a significant drop in blood pressure during or after an infusion.

Action: This is monitored closely by your care team during IV administration; the infusion is slowed or stopped by the treating clinician if this occurs. Report any lightheadedness or fainting to your care team immediately. (1)

Interactions

  • Other Class Ia antiarrhythmics (such as quinidine or disopyramide): additive cardiac and toxic effects; combination avoided or closely managed by a specialist. (1) (2)
  • Anticholinergic medicines: procainamide can enhance their effects on the heart's electrical conduction (AV node); used with caution together. (1) (2)
  • Cimetidine: reduces the body's clearance of procainamide and its active metabolite (NAPA), which may require a dosage adjustment. (2)
  • Neuromuscular blocking agents (used during anaesthesia) and certain antibiotics (kanamycin, neomycin, streptomycin): procainamide can potentiate their paralysing effects, with a risk of prolonged muscle weakness or breathing difficulty -- managed closely by the anaesthesia/care team. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Procainamide crosses the placenta. US labelling (pre-2015 pregnancy category system) classifies it as Category C -- animal reproduction studies have not been conducted, and it should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus, as judged by the treating specialist. (1) (2) (3) (4) (5)

Breastfeeding

Both procainamide and its active metabolite (N-acetylprocainamide, NAPA) pass into human breast milk and could pose a risk to a nursing infant. The decision to continue breastfeeding or continue the medicine should be made with your treating clinician, based on how much you need the medicine. (1) (2) (3) (4) (5)

Children

Not specifically addressed with dedicated paediatric dosing in the sources reviewed; use in children would be directed and dosed individually by a paediatric cardiology specialist. (1) (2) (3) (4) (5)

Elderly

Reduced kidney function in older adults delays procainamide clearance; a reduced frequency of dosing is generally required, with dosing guided by blood level monitoring. (1) (2) (3) (4) (5)

Hepatic_impairment

Reduced dosing frequency is required in liver disease, since procainamide clearance can be affected; monitored closely by the treating clinician. (1) (2) (3) (4) (5)

Renal_impairment

Reduced kidney function (lower creatinine clearance) prolongs procainamide's normally 3-4 hour elimination half-life; dosage and dosing frequency must be adjusted, guided by blood level monitoring where available. (1) (2) (3) (4) (5)

Source_ids

US-DAILYMED-PROCAINAMIDE-2026,CA-HC-PROCAN-SR-PM-2026 (1) (2) (3) (4) (5)

Monitoring

Before starting

  • Baseline complete blood count
  • Baseline ANA status where relevant
  • Baseline ECG and kidney/liver function

During treatment

  • Continuous ECG and vital-sign monitoring during intravenous administration, watching for QRS widening greater than 25%, prolonged QT/PR intervals, or AV block.
  • Complete blood counts (white cell, differential, platelet) weekly for the first 3 months of therapy, then periodically thereafter.
  • Periodic ANA testing during longer-term therapy, with prompt clinical assessment if a positive titer or lupus-like symptoms develop.
  • Blood pressure monitoring during IV loading, with temporary discontinuation if systolic pressure drops significantly.
(1) (2)

Storage

Procainamide injection is stored and handled by hospital pharmacy/clinical staff according to the product's specific storage requirements; oral extended-release tablets (where available) should be stored at room temperature, protected from moisture, and out of reach of children.

Study the drug class: Class I antiarrhythmics

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information and the Health Canada Procan SR/injection product monographs reviewed for this dossier; verify against the current full label before prescribing or administering.

United States

Indication: Life-threatening ventricular arrhythmias (hospital-initiated)

Dose summary: IM: ~50 mg/kg/day divided q3-6h. IV loading: 100 mg direct injection q5min (max 50 mg/min) to 500 mg total, or 500-600 mg infusion over 25-30 min; max single dose 1 g. Maintenance IV infusion: 2-6 mg/min.

Renal context: Reduced creatinine clearance prolongs the normal 3-4 hour half-life; reduce dosing frequency and monitor plasma levels where available; renal excretion reduced ~25% at age 50 and ~50% at age 75. (1)

Canada

Indication: Ventricular/atrial arrhythmias; extended-release maintenance after stabilisation

Dose summary: Procan SR maintenance: ~50 mg/kg/day divided q6h, tablets not to be crushed or chewed; injection dosing as per standard-release procainamide product information.

Renal context: Reduce dosing frequency in renal impairment, hepatic disease, and low cardiac output states; monitor plasma procainamide/NAPA concentrations. (2)

Mechanism of action

Hepatic guidance

Reduced dosing frequency required in hepatic impairment; monitor clinically and, where available, via plasma drug concentrations.

Overdose note

Managed with supportive care, vasopressors for hypotension, and hemodialysis (which significantly reduces serum half-life and effectively removes procainamide/NAPA); peritoneal dialysis is not effective; ventricular pacing may be used preventively if heart block develops. (1) (2)

Frequently asked questions

Is procainamide available in the US, UK, Europe, Canada, Australia, and New Zealand?

Availability genuinely differs by country. It is confirmed currently authorised and marketed as a generic injectable in the United States, and Canada has real, current Health Canada product monographs for both an extended-release tablet (Procan SR) and an injection. The UK's own licensed injectable product (Pronestyl) has been discontinued, so procainamide is now obtainable in the UK only via special-order/unlicensed import. A current registration record could not be confirmed for the European Union, Australia, or New Zealand in the sources checked for this page -- rather than guess, that is shown as unable to verify. (1) (2) (3) (4) (5)

Why does procainamide have a boxed warning about lupus?

Because a genuine, well-documented effect of prolonged procainamide use is the development of a positive antinuclear antibody (ANA) blood test, sometimes together with a lupus-like illness (joint pain, fever, skin changes, chest-wall pain). This is why your clinician may check ANA levels periodically and will reassess whether to continue procainamide if a positive result or symptoms appear. (1)

Why are regular blood tests needed during procainamide treatment?

Because procainamide carries a real, serious risk (about 0.5% of patients) of severe blood-cell problems, including agranulocytosis, a dangerous drop in the white blood cells that fight infection -- fatal in an estimated 20-25% of reported agranulocytosis cases. Since most cases occur within the first 12 weeks, weekly complete blood counts are recommended for the first 3 months of treatment, then periodically afterward. (1) (2)

What is the mechanism of action of procainamide hydrochloride?

Procainamide is a Class Ia antiarrhythmic that blocks fast sodium channels, slowing conduction velocity and prolonging the effective refractory period and action potential duration in atrial and ventricular tissue. Its active metabolite, N-acetylprocainamide (NAPA), has additional Class III antiarrhythmic activity. (1) (2)

What is the generic name of Procainamide?

The generic name is procainamide hydrochloride. (1) (2)

What class of drug is procainamide hydrochloride?

Procainamide is classed as: Class Ia antiarrhythmic (sodium channel blocker). (1) (2)

References

  1. PROCAINAMIDE HYDROCHLORIDE injection, solution -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · dated 2025-01-01 · accessed 2026-07-30 · source 1
  2. PROCAN SR (procainamide hydrochloride) extended-release tablets -- Product MonographHealth Canada -- Product Monograph (Procan SR, procainamide hydrochloride extended-release tablets), cross-checked via the RxMed Canadian Compendium of Pharmaceuticals and Specialties (CPS) monograph mirror · Canada · dated 2023-06-28 · accessed 2026-07-30 · source 2
  3. Procainamide hydrochloride -- BNF code 0203020S0; dm+d record for Pronestyl 1g/10ml solution for injectionBritish National Formulary (BNF) classification, cross-checked against OpenPrescribing (NHS England GP prescribing data) and the NHS Business Services Authority dm+d browser · United Kingdom · dated 2026-01-01 · accessed 2026-07-30 · source 3
  4. Procainamide -- healthdirect medicine information pagehealthdirect Australia (Australian Government-funded consumer medicines information service) · Australia · dated 2026-07-30 · accessed 2026-07-30 · source 4
  5. Drug-induced Lupus (Medsafe Prescriber Update article, March 2017) -- procainamide adverse-reaction-reporting contextMedsafe (New Zealand Medicines and Medical Devices Safety Authority) -- safety-article context, not a product data sheet · New Zealand · dated 2017-03-01 · accessed 2026-07-30 · source 5

Brand names by country

Single-ingredient procainamide hydrochloride names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • PROCAINAMIDE HCI100 mg/mL · hf acquisition co llc, dba healthfirst

United Kingdom

  • Pronestyl 1g/10ml solution for injection (discontinued licensed product) (3)discontinued licensed product now special order only · 1 g/10 mL injection (historical) · Bristol-Myers Squibb Pharmaceuticals Ltd (historical)

Canada

  • PROCAINAMIDE HYDROCHLORIDE INJ.
  • PROCAN SR
View brands in additional countries.

This page provides general reference information about procainamide and is not a substitute for advice from the prescriber or care team managing your treatment. Procainamide is a hospital/specialist-administered medicine; all dosing, monitoring, and treatment decisions should be made with your treating clinician.

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