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All about: Procainamide HCl

Big Image Pronouncation: (pro-CANE-uh-mide HIGH-droe-KLOR-ide)
Class: Antiarrhythmic agent

Trade Names:
- Tablets, sustained-release 500 mg
- Tablets, extended-release 1000 mg

Trade Names:
- Tablets 250 mg
- Tablets 375 mg
- Tablets 500 mg
- Capsules 250 mg
- Capsules 375 mg
- Capsules 500 mg
- Injection 100 mg/mL
- Injection 500 mg/mL

Trade Names:
- Tablets, sustained-release 500 mg

Apo-Procainamide (Canada)
Procan SR (Canada)

Mechanism of Action


Increases effective refractory period of atria and bundle of His-Purkinje system; reduces impulse conduction velocity and myocardial excitability in atria, Purkinje fibers, and ventricles.



Rapid absorption (IM), immediate absorption (IV). Well absorbed from entire small intestinal surface (oral).


Protein binding is 15% to 20%, also bound to tissues of the heart, liver, lung, and kidney. Vd is 2 L/kg. The drug distributes into breast milk (procainamide and N-acetylprocainamide [NAPA]).


Metabolized in liver to NAPA, an active metabolite exerting significant antiarrhythmic activity. Approximately 25% of dose converted to NAPA, up to 40% conversion occurs in patients who are rapid acetylators.


The t 1/ 2 is 3 to 4 hr (normal renal function, procainamide) and approximately 6 hr (NAPA). Urinary excretion (6% to 52% NAPA, 30% to 60% as unchanged procainamide); a trace amount is excreted in urine as free and conjugated p-aminobenzoic acid.


60 to 90 min (oral), 15 to 60 min (IM), and immediate (IV).

Special Populations

Renal Function Impairment

Elimination t ½ is prolonged.


Elimination t ½ is prolonged.


In infants, t ½ and renal clearance are reduced.

Indications and Usage

Treatment of documented ventricular arrhythmias that are life threatening.


Complete heart block; idiosyncratic hypersensitivity; lupus erythematosus; torsades de pointes.

Dosage and Administration


PO 50 mg/kg/day in divided doses (q 3 hr for regular release; q 6 to 12 hr for sustained release, depending on the formulation).

IV 20 mg/min for 25 to 30 min as loading dose, then 2 to 6 mg/min for maintenance.

IM 50 mg/kg/day in divided doses q 3 to 6 hr until oral therapy is possible.


Safety not established. Following doses have been used:

PO 15 to 50 mg/kg/day in divided doses q 3 to 6 hr, max of 4 g/day;

IM 20 to 30 mg/kg/day in divided doses q 4 to 6 hr, max 4 g/day;

IV 3 to 6 mg/kg/dose over 5 min for loading dose, then 20 to 80 mcg/kg/min continuous infusion (max, 100 mg/dose or 2 g/day).

General Advice

  • Give sustained-release forms whole. Do not crush or allow patient to bite or chew them.
  • Prepare IV infusion solution using D5W. Use controlled infusion device.
  • IV solutions may turn slightly yellow or light amber on standing, but potency is not affected.
  • For direct IV injection, do not exceed maximal IV rate of 50 mg/min and do not give more than 100 mg in any 5-min period.
  • Wait 3 to 4 hr after last IV dose before first oral dose.


  • IV infusion solutions may be stored at room temperature (59° to 86°F) for 24 hr or for 7 days if refrigerated. Discard IV infusion solutions that are darker than light amber.
  • Store capsules at controlled room temperature (59° to 86°F). Store extended-release tablets at controlled room temperature (68° to 77°F). Store injection at controlled room temperature (59° to 86°F). Protect from freezing.

Drug Interactions

Amiodarone, cimetidine, trimethoprim

May increase procainamide and NAPA concentrations.

Cisapride, quinolone antibiotics (eg, gatifloxacin), thioridazine, ziprasidone

May increase the risk of life-threatening cardiac arrhythmias, including torsades de pointes.

Group 1a antiarrhythmic agents (eg, quinidine)

Coadministration with procainamide is contraindicated.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Proarrhythmic effects; hypotension.


Dizziness; weakness; depression; psychosis with hallucinations.


Angioneurotic edema; urticaria; pruritus; flushing; rash.


Bitter taste.


Nausea; vomiting; anorexia; abdominal pain.


Neutropenia; thrombocytopenia; hemolytic anemia; agranulocytosis.


Lupus erythematosus-like syndrome.



Cardiovascular effects

Procainamide has proarrhythmic effects. May cause or aggravate CHF or produce severe hypotension, especially in patients with CHF, acute ischemic heart disease, or cardiomyopathy.


Agranulocytosis, bone marrow depression, neutropenia, hypoplastic anemia, and thrombocytopenia have been reported and may occur, usually within first 12 wk of therapy at recommended doses. Use caution in patients with pre-existing marrow failure or cytopenia.

Positive ANA titer

Chronic administration may result in positive titers with or without symptoms of lupus erythematosus-like syndrome. Approximately 50% of patients will develop ANA within 2 to 18 mo of starting therapy.


Category C .


Excreted in breast milk.


Safety and efficacy not established.


Consider the possibility of cross-sensitivity to procainamide in patients sensitive to procaine or other ester-type local anesthetics.

Renal Function

Individual dose adjustment may be necessary.

Special Risk Patients

Elderly patients and patients with renal, hepatic or cardiac insufficiency will require smaller or less frequent doses. Individual dosage adjustment will be necessary.

Tartrazine Sensitivity

Some tablet forms contain tartrazine.

Sulfite Sensitivity

Parenteral forms contain sulfites.

Asymptomatic PVCs

Avoid use of product in treatment of patients with this condition.

Blood dyscrasias

Agranulocytosis, bone marrow depression, neutropenia, hypoplastic anemia, and thrombocytopenia have been reported; monitor carefully.

Complete heart block

Do not administer to patients with complete heart block because of effects in suppressing nodal or ventricular pacemakers and hazard of asystole.

Concurrent antiarrhythmic agents

May see enhanced prolongation of conduction or depression of contractility and hypotension.

Digitalis intoxication

Use with caution treating arrhythmias associated with digitalis intoxication.

First-degree heart block

Use with caution if first-degree heart block develops during procainamide therapy.

Myasthenia gravis

Patients may experience increase of muscle weakness. Observe closely.

Predigitalization for atrial flutter or fibrillation

Cardiovert or digitalize patient prior to procainamide therapy to avoid enhancement of AV conduction.



Hypotension, widening of QRS complex, prolonged QT and PR intervals, ventricular tachyarrhythmias.

Patient Information

  • Tell patient to take medication with full glass of water.
  • Caution patient not to crush or chew sustained-release capsules.
  • Explain that this medication should be taken throughout 24-hr period.
  • Explain importance of informing other health care providers or dentists about therapy before surgical or dental procedures.
  • Emphasize importance of drug compliance. Caution patient not to make up for missed doses.
  • Instruct patient to report the following symptoms to health care provider immediately: difficulty breathing, pounding or irregular heartbeat, joint pain, fever, chills, skin rash, continued dizziness.
  • Explain that diarrhea, nausea, dizziness, or loss of appetite may occur and to contact health care provider if symptoms are bothersome.
  • Advise patient that drug may cause dizziness and to use caution when driving or performing other tasks requiring mental alertness.

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