Cardiology | Antiarrhythmic Drug Guide | Class Ia | Procainamide

Procainamide

IV Dose Loading dose: 10-15 mg/kg (yes, milligrams)maximum 1.0 gram maximum rate 50 mg/min or 0.5 mg/kg/min Drip: 30-80 ug/kg/min (yes, micrograms)
Oral dose 50-100 mg/kg/day divided q 3-4 hours (q 6 hours for slow release forms)
Levels PC 4-8, may go up to 12 ug/ml NAPA <40 ug/ml is well tolerated. ?usefulness
Kinetics Peak levels at 1 hour after oral dose. Increased volume of distribution in heart failure. Elimination half-life of PC: 2.5-4.7 hours in adults.13.5 hours in neonates.7 hours in 7-12 year olds.1st order to at least to 26 ug/ml. For slow release forms, t 1/2 = 6-7 hours. Elimination half-life of NAPA: 6-8 hours.
Cautions QRS >25% prolongation: no further dosage increases QTc >= 0.500 : stop drug
Interactions Amiodarone increases PC and NAPA levels by 57% and 32% respectively. Cimetidine increases PC half-life. Propranolol decreases t 1/2, increases Vd. Digoxin: no known interaction.
Preparations Pronestyl non-scored tabs: 250, 375, 500 mg. Capsules 250, 375, 500 mg. Pronestyl SR non-scored matrix tabs: 500 mg. Procan SR wax matrix tabs: 250, 500, 750, 1000 mg.(>500 tabs scored) Pronestyl injection 1000 mg vials:100 mg/cc or 500 mg/cc.
FDA approval in children no

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