Quinolones
Severe
Textbook
Increased risk of QT interval prolongation and torsades de pointes arrhythmias.
Quinolones should be used with caution in patients on class IA antiarrhythmics.
Source: G&G 14e · p1144
Drug reference
procainamide
Na+ Channel Blocker (Class IA), K+ Channel Blocker · Antiarrhythmic
Na+ Channel Blocker (Class IA), K+ Channel BlockerAntiarrhythmicATC C01BA02
CDSCO approvedATC C01BA02
EXCRETION
—
not curated
INTERACTIONS
12 major
SEVERE in our sources
PREGNANCY
—
not curated
Top interactionssee all 12 →
- QuinolonesSevereTextbookG&G 14e · p1144
- AbarelixSevereDatabaseDDInter
- AbirateroneSevereDatabaseDDInter
- AdenosineSevereDatabaseDDInter
Mechanism
Procainamide blocks open Na+ channels (with intermediate τrecovery) and prolongs cardiac action potentials in most tissues, probably by blocking outward K+ current(s). It decreases automaticity, increases refractory periods, and slows conduction.
Indications
Acute therapy of many supraventricular arrhythmiasAcute therapy of many ventricular arrhythmiasTermination of monomorphic ventricular tachycardia (VT)Termination of some supraventricular arrhythmiasWPW reciprocal ventricular tachycardiasPrevention of recurrences of ventricular fibrillation (VF)Alternative regimen for sustained ventricular tachycardia
Dosing
- Adult
- Loading: 10–17 mg/kg (IV) at a rate of 20 mg/min. Maintenance: 1–4 mg/min (IV); 250–750 mg q3h; 500–1000 mg q6h (slow-release).
- Renal adjustment
- Reduction of dose and dosing frequency, and monitoring of plasma concentrations required in renal failure.
Pharmacokinetics
Half-life
3–4 h (parent drug); 6–10 h (N-acetyl procainamide)
Bioavailability
>80%
Protein binding
Not specified
Metabolism
Hepatic by N-acetyl transferase to N-acetyl procainamide (active metabolite)
Excretion
67 ± 8%
Contraindications
- Infranodal conduction disease
- Arthritis (due to chronic procainamide use)
Side effects
Common
Nausea (dose-related with oral therapy)RashSmall-joint arthralgias (early symptom of lupus syndrome)NauseaVomitingWeaknessMental confusionHallucinations (at higher doses)Flushing (on rapid i.v. injection)Hypotension (on rapid i.v. injection)Rashes (hypersensitivity)Fever (hypersensitivity)Angioedema (hypersensitivity)
Serious
- Hypotension (at high concentrations, especially during acute IV loading)
- Marked slowing of conduction (at high concentrations)
- Torsades de pointes (particularly when N-acetyl procainamide >30 μg/mL)
- Bone marrow aplasia (0.2% of patients)
- Drug-induced lupus syndrome (25% to 50% with chronic use, may include pericarditis with tamponade, renal involvement is unusual)
- haemolysis (in G-6PD deficient individuals)
- lupus (mainly in slow acetylators)
- Cardiac toxicity
- Torsades de pointes
- Agranulocytosis (rare)
- Aplastic anaemia (rare)
- Systemic lupus erythematosus (SLE) (with long-term high dose, especially in slow acetylators)
Drug interactions
Abarelix
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Abiraterone
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Adenosine
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Alfuzosin
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Alimemazine
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Amiodarone
Severe
Database
Increased plasma concentrations of procainamide.
Dosages of other antiarrhythmics usually require reduction during amiodarone therapy.
Source: DDInter
Amisulpride
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Amitriptyline
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Amoxapine
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Anagrelide
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Apalutamide
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Related guidelines
Ask House about procainamide
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Sources: KD Tripathi 7e, Goodman & Gilman 14e, Harrison 22e·Verified: 2026-05-10 · House clinical team