Procainamide

Indications

Procainamide is used for: Arrhythmia

Adult Dose

Arrhythmia 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 Hepatic Impairment Reduce dose by 50%

Child Dose

Arrhythmia 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

Renal Dose

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

Administration

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)

Contra Indications

Heart block, SLE, heart failure, hypotension, myasthenia gravis, digoxin toxicity, lactation.

Precautions

Myocardial damage or severe organic heart disease, asthma. Perform regular blood tests. Screen for lupus erythematosus. Serum antinuclear factor should be carried out before and regularly during therapy. Pregnancy, elderly, hepatic and renal impairment. May worsen torsade de pointes. Pre-treatment with digoxin may be necessary if procainamide is used in the treatment of atrial tachycardia. IV admin may cause severe hypotension, thus slow inj and monitoring of ECG and BP are recommended.

Pregnancy-Lactation

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

Interactions

May enhance effects of antihypertensives, other antiarrhythmics, antimuscarinics and neuromuscular-blocking drugs and diminish those of parasympathomimetics. Increased clearance when used with alcohol. Increased plasma concentrations and toxicity of procainamide when used with trimethoprim. Potentially Fatal: Increased risk of arrhythmias with terfenadine and antipsychotics that prolong QT interval.

Adverse Effects

Side effects of Procainamide : >10% Increased antinuclear antibodies (50%) SLE-like syndrome (30%) 1-10% Hypotension (5%) Frequency Not Defined Arrhythmias Asystole Heart block Wide PR or QRS Asthenia Ataxia Depression Chills Psychosis Abdominal pain Bitter taste N/V Myopathy Rash Leukopenia

Mechanism of Action

Procainamide directly interferes with depolarization of the cell membrane by blocking the fast inward current of Na into cardiac cells. It slows the rate of change of the depolarization phase of the action potential, moderately prolong the PR, QRS and QT intervals on ECG monitoring. It also has local anesthetic properties.