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CARDIOVASCULAR SYSTEM › CARDIAC THERAPY › ANTIARRHYTHMICS, CLASS I AND III › Antiarrhythmics, class Ia
prajmaline
C01BA08
Adult Dosing
- Ventricular arrhythmias: 20-40 mg orally 3 times daily
- Maintenance: 20 mg orally 1-2 times daily
- Max daily dose: 120 mg
Pediatric Dosing
- Safety and efficacy not established in pediatric patients
Indications
- Treatment of symptomatic ventricular arrhythmias
- Prophylaxis of paroxysmal supraventricular tachycardia
Mechanism of Action
- Class IC antiarrhythmic agent in Vaughan Williams classification
- Inhibits fast inward sodium current in myocardial cell membranes
- Slows upstroke of cardiac action potential (Phase 0) and conduction velocity
- Prolong effective refractory period in the His-Purkinje system
Contraindications
- Known hypersensitivity to prajmaline or ajmaline derivatives
- Pre-existing second- or third-degree atrioventricular block without a pacemaker
- Severe bradycardia or sick sinus syndrome
- Decompensated heart failure
- Severe renal or hepatic impairment
- Concomitant use of drugs that prolong the QT interval
Adverse Reactions
- Proarrhythmia (new or worsened arrhythmias)
- Atrioventricular block and bradycardia
- Heart failure exacerbation
- Hypotension
- Nausea, vomiting, and abdominal discomfort
- Dizziness, headache, and fatigue
- Elevated liver enzymes and intrahepatic cholestasis
Drug Interactions
- Other antiarrhythmic drugs (additive negative inotropic and chronotropic effects)
- Beta-blockers and calcium channel blockers (enhanced risk of bradycardia and AV block)
- CYP2D6 inhibitors may increase plasma concentrations of prajmaline
- Drugs prolonging the QT interval (increased risk of Torsades de Pointes)
Curated Content: Needs Vetting Before Put to Clinical Use