Pronestyl

Pronestyl [pro-nes´til]

trademark for preparations of procainamide, a cardiac depressant.

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procainamide hydrochloride

Apo-Procainamide (CA), Procanbid, Pronestyl, Pronestyl-SR (CA)

Pharmacologic class: Membrane stabilizer

Therapeutic class: Antiarrhythmic (class IA)

Pregnancy risk category C

FDA Boxed Warning

• Prolonged use often leads to positive antinuclear antibody (ANA) test, with or without symptoms of lupus erythematosus-like syndrome. If positive ANA titer develops, weigh benefits versus risks of continued therapy.

Action

Decreases myocardial excitability by inhibiting conduction velocity. Also depresses myocardial contractility.

Availability

Capsules: 250 mg, 375 mg, 500 mg

Injection: 100 mg/ml, 500 mg/ml

Tablets: 250 mg, 375 mg, 500 mg

Tablets (extended-release): 250 mg, 500 mg, 750 mg, 1,000 mg

⊘Indications and dosages

➣ Life-threatening ventricular arrhythmias

Adults: 100 mg by slow I.V. push at a rate of 50 mg/minute, repeated q 5 minutes until arrhythmia subsides, up to a maximum advisable dosage of 1 g. Alternatively, loading dose of 500 to 600 mg by I.V. infusion over 25 to 30 minutes. With either I.V. method, maximum loading dose is 1 g. When arrhythmia subsides, give continuous I.V. infusion of 2 to 6 mg/minute. Or 50 mg/kg I.M. in divided doses q 3 to 6 hours until patient can tolerate P.O. therapy.

For long-term maintenance, usual dosage is 50 mg/kg (extended-release) P.O. daily in equally divided doses q 6 hours. Or 50 mg/kg/day P.O. (prompt-release) in divided doses at 3-, 4-, or 6-hour intervals.

Dosage adjustment

• Renal impairment

Contraindications

• Hypersensitivity to drug, tartrazine, procaine, or sulfites
• Complete heart block
• Torsades de pointes
• Lupus erythematosus

Precautions

Use cautiously in:
• procaine hypersensitivity, renal impairment, ischemic heart disease, heart failure, first-degree heart block, atypical ventricular tachycardia, myasthenia gravis, systemic lupus erythematosus, cytopenia
• patients receiving other antiarrhythmics concurrently
• pregnant or breastfeeding patients
• children.

Administration

☞ Ask patient about procaine sensitivity before giving; cross-sensitivity may occur.
• Don't crush tablets.
• For I.V. use, dilute with dextrose 5% in water.
• Administer I.V. doses with patient in supine position to avoid hypotensive effects.
• When giving by I.V. infusion, use infusion pump to ensure that drug infuses at 50 mg/minute or less.
☞ Don't leave patient's bedside during I.V. administration.

Route	Onset	Peak	Duration
P.O.	Unknown	90-120 min	Unknown
I.V.	Immediate	Immediate	Unknown
I.M.	10-30 min	15-60 min	Unknown

Adverse reactions

CNS: headache, dizziness, confusion, psychosis, restlessness, asthenia, depression, neuropathy, seizures

CV: hypotension, bradycardia, atrioventricular block, ventricular fibrillation, ventricular asystole, cardiovascular collapse, cardiac arrest

GI: nausea, vomiting, diarrhea, anorexia

Hematologic: hemolytic anemia, agranulocytosis, thrombocytopenia, neutropenia

Skin: rash, urticaria, pruritus, flushing

Other: bitter taste, lupuslike syndrome, edema

Interactions

Drug-drug. Amiodarone: increased procainamide blood level and risk of toxicity

Anticholinesterase drugs: decreased anticholinesterase effects

Antihypertensives: additive hypotension

Beta-adrenergic blockers, cimetidine, ranitidine, trimethoprim: increased procainamide blood level

Lidocaine: additive cardiodepressant action, conduction abnormalities

Neuromuscular blockers: increased skeletal muscle relaxation

Other antiarrhythmics: additive or antagonistic effects, additive toxicity

Trimethoprim: increased pharmacologic effect of procainamide

Drug-herbs. Henbane: increased anticholinergic activity

Jimsonweed: adverse cardiovascular effects

Licorice: prolonged QT interval

Drug-behaviors. Alcohol use: altered drug blood level

Patient monitoring

☞ When giving I.V., stay at patient's bedside and monitor blood pressure and ECG continuously.
☞ If ECG shows prolonged QT interval and QRS complexes, heart block, or worsening arrhythmia, stop drug therapy, run rhythm strip, and contact prescriber immediately.
• Assess blood levels of procainamide and N-acetylprocainamide (drug's active metabolite).
☞ Monitor electrolyte levels, CBC, and antinuclear antibody titers. Watch for signs and symptoms of blood dyscrasias.
• Evaluate patient for signs and symptoms of lupuslike syndrome.

Patient teaching

• Tell patient not to crush tablets.
☞ Advise patient to immediately report cardiovascular symptoms or bleeding tendency.
• Emphasize importance of taking exactly as prescribed. Advise patient to use alarm clock to help him remember to take nighttime doses.
• Advise patient to avoid alcohol.
• Instruct patient not to take herbal remedies unless prescriber approves.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, herbs, and behaviors mentioned above.