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procainamide; novacainamide (Procan Pronestyl-SR)

Tradenames: Procan, Pronestyl-SR. Indications: 1) atrial fibrillation a) chemical cardioversion b) preventing recurrence of atrial fibrillation 2) paroxysmal supraventricular tachycardia (PSVT) 3) ventricular tachycardia Contraindications: (cautions) 1) Avoid in patients with a history of torsades de pointes 2) discontinue use with prolongation of QT interval a) QTc >500 ms b) prolongation of QTc by more than 25% 3) complete heart block (2nd or 3rd degree) without pacemaker 4) myasthenia gravis 5) systemic lupus erythematosus Dosage: 1) oral a) loading dose of 1 gram in 2 divided doses 2 hours apart b) maintenance: 500-1000 mg PO QID or 50 mg/kg/day c) sustained-release: 50 mg/kg or 2-4 g PO QD 2) IV infusion: a) loading dose of 1-1.5 g @ 20-30 mg/min or 15-20 mg/kg b) 1-4 mg/min (20-80 ug/kg/min) [3] c) 100 mg IV every 10 min or continuous infusion @ < 20 mg/min (150 mL/hr) until: 1] QRS widens > 50% 2] dysrhythmia suppressed 3] hypotension d) 17 mg/kg or 1 g infusion of 2g in 250 mL D5W (8 mg/mL) at 20-50 mg/min (20 mg/min stable, 50 mg/min unstable) 3) intermittent IV/IM 1-6 g/day in divided doses; max 9 g/day 4) decrease maintenance dose in patients with liver or renal disease 5) when converting from IV to PO, continue IV for 1 hours after administration of non-sustained release tablet, 2 hours after sustained release tablet Tabs: 250, 375, 500 mg Sustained release: 250, 500, 750, 1000 mg Injection: 100 mg/mL (10 mL), 500 mg/mL (2 mL) Pharmacokinetics: 1) oral bioavailability is 83% 2) minimal binding to plasma proteins 3) metabolized by liver to N-acetylprocainamide (NAPA), an active class III antiarrhythmic agent 4) 67% of the drug is excreted unchange in the urine 5) clearance is variable, based on acetylator status & renal function 6) elimination 1/2life a) 3 hours with normal renal function [3] b) may increase to 5-20 hours in patients with renal insufficiency 7) therapeutic range: 4-10 ug/mL (15-25 ug/mL for NAPA) 8) moderately dialyzable: 20-50% Monitor: - CBC weekly for the 1st 3 months of therapy & periodically thereafter Adverse effects: 1) gastrointestinal (GI) a) nausea/vomiting b) diarrhea 2) lupus-like syndrome (30-50%) a) fever b) pleuropericarditis (pleural effusion) c) hepatomegaly d) arthralgias & myalgias e) skin rash f) spares kidneys g) up to 1/3 of patients on chronic procainamide h) may be more likely in 'slow acetylators' i) antinuclear antibodies in 75% of patients on chronic procainamide therapy 3) hemotologic a) bone marrow suppression (0.5%) - agranulocytosis, neutropenia, hypoplastic anemia thrombocytopenia b) hemolytic anemia c) positive direct antiglobulin (Coomb's) test (DAT) 4) cardiac arrhythmias a) QT prolongation - including torsades de pointes b) bradycardia c) AV node block d) asystole e) tachycardia f) QRS widening 5) hypotension may develop with rapid IV infusion 6) neurologic confusion, disorientation, hallucinations, depression, dizziness, lightheadness Drug interactions: 1) avoid other agents which prolong the QT interval a) class Ia antiarrhythmics b) class III antiarrhythmics c) phenothiazines d) tricyclic antidepressants e) erythromycin f) terfenadine g) astemizole 2) propranolol, amiodarone, cimetidine, ranitidine increase procainamide & NAPA levels 3) quinidine & trimethoprim increase both procainamide & NAPA levels 4) neuromuscular blockade of succinylcholine may be increased Laboratory: 1) specimen: a) serum, plasma (heparin, EDTA, oxalate) b) stable to 2 weeks at 2-8 degrees C c) stable for 6 months at -20 degrees C d) assay procainamide together with N-acetylprocainamide 2) methods: GLC, HPLC, EIA, FPIA 3) interferences: hemolysis, ichterus & lipemia may interfere with EIA & FPIA Mechanism of action: 1) class Ia antiarrhythmic agent 2) increases effective refractory period of: a) the atria b) bundle of His-Purkinje system c) ventricles 3) may decrease systemic blood pressure by causing peripheral ganglionic blockade 4) weak anticholinergic activity 5) slight negative inotropic activity 6) its major metabolite, N-acetyl procainamide, is a class III antiarrhythmic agent

Interactions

drug interactions drug adverse effects of antiarrhythmic agent, Group IA

Related

procainamide in serum/plasma

Specific

N-acetylprocainamide (NAPA, Acecainide)

General

aminobenzoate antiarrhythmic agent, Group IA benzamide

Properties

MISC-INFO: elimination route KIDNEY 76-93% LIVER 7-24% 1/2life 2.5-5 HOURS therapeutic-range 4-10 UG/ML toxic-range >10 NG/ML protein-binding 15% elimination by hemodialysis + pregnancy-category C safety in lactation ?

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (ed), Companion Handbook, McGraw Hill, NY, 1994
  3. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 Department of Veterans Affairs, VA National Formulary - non formulary drug request
  4. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  5. Clinical Guide to Laboratory Tests, NW Tietz (ed) 3rd ed, WB Saunders, Philadelpha 1995
  6. ACLS - The Reference Texbook ACLS: Principles & Practice, Cummins RO et al (eds), American Heart Association, 2003 ISBN 0-87493-341-2