procainamide (Rx)

Brand and Other Names:Pronestyl (SR)
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Dosing & Uses


Dosage Forms & Strengths

injection solution

  • 100 mg/mL
  • 500mg/mL


Adjust dose to patient's response

IM Administration

  • 0.5-1 g IM q4-8hr

IV Administration

  • Loading dose: 100-200 mg/dose or 15-18 mg/kg; infuse slowly over 25-30 min not to exceed 50 mg/min; may repeat q5min PRN not to exceed 1 g  
  • Maintenance: 1-4 mg/min by continuous IV infusion
  • Renal impairment:

Renal Impairment

Reduce loading dose to 12 mg/kg

Reduce infusion to one third in moderate renal or cardiac impairment and two thirds in severe renal or cardiac impairment

Hepatic Impairment

Reduce dose by 50%

Dosage Forms & Strengths

injection solution

  • 100 mg/mL
  • 500mg/mL


Adjust dose to patient's response

IM Administration

  • 20-30 mg/kg/day IM divided q4-6hr; not to exceed 4 g/day

IV Administration

  • Loading dose: 3-6 mg/kg IV over 5 minutes, not to exceed 100 mg/dose; may repeat q5-10min PRN not to exceed 15 mg/kg/dose
  • Maintenance: 0.02-0.08 mg/kg/min IV infusion; not to exceed 2 g/24 hours  


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            Adverse Effects


            Increased antinuclear antibodies (50%)

            SLE-like syndrome (30%)


            Hypotension (5%)

            Frequency Not Defined



            Heart block

            Wide PR or QRS






            Abdominal pain

            Bitter taste







            Black Box Warnings

            Positive ANA Titer

            • Long-term administration often leads to positive antinuclear antibody (ANA) test result
            • Positive result may occur with or without lupus erythematosus-like syndrome symptoms If a positive ANA titer develops, assess benefits vs risks of continuing procainamide


            • National Heart, Lung, and Blood Institute's Cardiac Arrhythmia Suppression Trial (CAST): Excessive mortality or nonfatal cardiac arrest (7.7%) shown with encainide or flecainide compared with placebo (3%)
            • CAST was a long-term, multicenter, randomized, double-blind study in patients with asymptomatic non-life-threatening ventricular arrhythmias who had a myocardial infarction >6 days but <2 yr previously
            • Average duration of treatment w/ encainide or flecainide in CAST was 10 months
            • Applicability of CAST results to other populations (eg, patients without recent MI) is uncertain
            • Reserve use of Class IC antiarrhythmics for life-threatening ventricular arrhythmias: Considering the known proarrhythmic properties of procainamide & lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, procainamide use, as well as other antiarrhythmic agents, should be reserved for patients with life-threatening ventricular arrhythmias

            Blood Dyscrasias

            • Agranulocytosis, bone marrow depression, leukopenia, neutropenia, aplastic/hypoplastic anemia, thrombocytopenia, & sequelae such as septicemia & septic shock have been reported at a rate of ~0.5%
            • Most reported within recommended dosage range and within initial 3 months of treatment
            • Fatalities have occurred (~20-25% mortality rate in reported agranulocytosis cases)
            • Perform complete blood counts, including white cell, differential, & platelet counts at weekly intervals for the first 3 months & then frequently thereafter
            • Check blood count if the patient develops any signs of infection (eg, fever, chills, sore throat, stomatitis), bruising, or bleeding.
            • If any of these hematologic disorders is identified, discontinue drug & initiate appropriate treatment
            • Blood counts usually return to normal within 1 month of discontinuation
            • Caution in patients with preexisting marrow failure or cytopenia


            Hypersensitivity to procainamide or other ingredients

            Complete heart block, 2°/3° AV block, SLE, torsade de pointes


            May produce life-threatening hematologic disorders (leukopenia, agranulocytosis)

            Consider toxicity if serum level >12 mg/L [51 umol/L]

            May exacerbate arrhythmias or produce paradoxical ventricular tachycardia in AFib/AFlutter patients

            Exercise caution in arrhythmias associated with digitalis intoxication; drug can suppress digitalis-induced arrhythmias; however, concomitant marked disturbance of atrioventricular conduction may result in additional depression of conduction and ventricular asystole or fibrillation; consider use only if discontinuation of digitalis and therapy with potassium, lidocaine, or phenytoin are ineffective

            Exercise caution if patient exhibits or develops first-degree heart block while receiving therapy; reduce dose if it occurs; if block persists despite dose reduction, evaluate whether to continue therapy by weighing benefit versus risk of increased heart block

            Prior to therapy, cardiovert or digitalize patients with atrial flutter or fibrillation to avoid enhancement of A-V conduction which may result in ventricular rate acceleration beyond tolerable limits; adequate digitalization reduces but does not eliminate possibility of sudden increase in ventricular rate as atrial rate is slowed by drug in these arrhythmias

            Use caution in patients with congestive heart failure, and those with acute ischemic heart disease or cardiomyopathy, when administering therapy; even slight depression of myocardial contractility may further reduce cardiac output of damaged heart

            May produce enhanced prolongation of conduction or depression of contractility and hypotension when used concurrently with other Group 1A antiarrhythmic agents such as quinidine or disopyramide, especially in patients with cardiac decompensation; reserve such use for patients with serious arrhythmias unresponsive to single drug and administer only if close observation is possible

            Renal insufficiency may lead to accumulation of high plasma levels from conventional doses of drug, with effects similar to those of overdosage, unless dosage is adjusted for individual patient

            Worsening of symptoms of myasthenia gravis may occur from therapy due to its procaine-like effect on diminishing acetylcholine release at skeletal muscle motor nerve endings; administration of therapy may be hazardous without optimal adjustment of anticholinesterase medications and other precautions

            Injection contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people; overall prevalence of sulfite sensitivity in general population is unknown and probably low; sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people

            Closely observe patients for possible hypersensitivity reactions Immediately after initiation of therapy

            Bear in mind that in conversion of atrial fibrillation to normal sinus rhythm by any means, may cause dislodgement of mural thrombi, which may lead to embolization

            QRS monitoring

            • Continued frequent periodic monitoring of vital signs and electrocardiograms advised after achieving and maintaining therapeutic plasma concentrations and satisfactory electrocardiographic and clinical responses
            • If evidence of QRS widening of more than 25 percent or marked prolongation of Q-T interval occurs, overdosage should be considered, and interruption of the infusion is advisable if a 50 percent increase occurs
            • Elevated serum creatinine or urea nitrogen, reduced creatinine clearance or history of renal insufficiency, as well as use in older patients (over age 50), provide grounds to anticipate that less than the usual dosage or infusion rate may suffice, since the urinary elimination of PA and NAPA may be reduced, leading to gradual accumulation beyond normally-predicted amounts
            • If facilities are available for measurement of plasma procainamide and NAPA, or acetylation capability, individual dose adjustment for optimal therapeutic levels may be easier, but close observation of clinical effectiveness is the most important criterion

            Blood pressure and ECG monitoring

            • Monitor blood pressure with patient supine during parenteral, especially intravenous, administration of drug
            • There is a possibility that relatively high although transient plasma levels of drug may be attained and cause hypotension before the drug can be distributed from plasma volume to its full apparent volume of distribution which is approximately 50 times greater
            • Caution should be exercised to avoid overly rapid administration of drug If blood pressure falls 15 mm Hg or more; temporarily discontinue therapy if it occurs; electrocardiographic (ECG) monitoring is advisable as well, both for observation of the progress and response of the arrhythmia under treatment, and for early detection of any tendency to excessive widening of the QRS complex, prolongation of the P-R interval, or signs of heart block
            • Parenteral therapy with should be limited to use in hospitals in which monitoring and intensive supportive care are available, or to emergency situations in which equivalent observation and treatment can be provided

            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: crosses into breast milk, discontinue drug or do not nurse

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Class IA (membrane stabilizing) antiarrhythmic agent; inhibits recovery after repolarization resulting in decreasing myocardial excitability and conduction velocity

            Direct membrane depressant that decreases conduction velocity, prolongs refractoriness, decreases automaticity and reduces repolarization abnormalities


            Bioavailability: 75-95%

            Peak Plasma Time: 15-60 min (IV/IM)


            Protein Bound: 15-20%

            Vd: 2 L/kg (1.5 L if CHF)


            Acetylated in liver to form N-acetylprocainamide (NAPA) (active); ratio of procainamide/NAPA depends upon acetylator phenotype and renal function

            Metabolites (active): N-acetylprocainamide (NAPA)


            Half-Life: 2.5-4.7 hr (parent drug), 6-8 hr (NAPA); increased in renal impairment and geriatrics

            Renal Clearance: 150-600 mL/min

            Excretion: Urine (30-60%), minimal in bile

            Dialyzable: Yes (HD); no (PD)



            IV Incompatibilities:

            Additive: bretylium, esmolol, milrinone

            Y-site: milrinone

            IV Compatibilities

            Additive: dobutamine, lidocaine, netilmicin

            Y-site: famotidine, heparin, KCl, ranitidine, Vit B/C and Amiodarone

            IV Preparation

            Solution: 2 g/250 mL D5W or NS (8 mg/mL)

            Administration: infusion requires use of an infusion pump; run at 1-6 mg/min (7.5-45 mL/hr)

            Slight yellow color of soln will not alter potency; however,

            • Do not use when darker than light amber or if soln contains precipitate




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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.