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CARDIOVASCULAR SYSTEM › CARDIAC THERAPY › ANTIARRHYTHMICS, CLASS I AND III › Antiarrhythmics, class Ic
encainide
C01BC08
Forms & Strengths
- Capsules: 25 mg
- Capsules: 35 mg
- Capsules: 50 mg
Adult Dosing
- Initial dose: 25 mg orally every 8 hours
- Titration: May increase to 35 mg or 50 mg every 8 hours based on clinical response and ECG monitoring
- Maximum recommended dose: 50 mg every 8 hours
Pediatric Dosing
- Safety and efficacy in pediatric patients have not been established
Indications
- Life-threatening ventricular arrhythmias such as sustained ventricular tachycardia
Mechanism of Action
- Class IC antiarrhythmic agent
- Slows conduction in the cardiac-sodium channels (fast inward sodium current)
- Increases ventricular refractoriness and prolongs PR and QRS intervals with minimal effect on action potential duration
Contraindications
- Pre-existing second- or third-degree AV block, and right bundle branch block when associated with left hemiblock (unless a pacemaker is present)
- Cardiogenic shock
- Known hypersensitivity to encainide
- History of myocardial infarction with asymptomatic ventricular arrhythmias (historically associated with increased mortality per CAST)
Adverse Reactions
- Proarrhythmia (new or worsened arrhythmias)
- Dizziness
- Blurred vision
- Headache
- Nausea
- Tremor
- Conduction abnormalities (prolonged PR, QRS, QT intervals)
Drug Interactions
- Beta-blockers: May cause additive negative inotropic and chronotropic effects
- Cimetidine: May decrease the hepatic clearance of encainide and increase plasma concentrations
- Other Class I or Class III antiarrhythmic drugs: Potential for additive cardiac depression and proarrhythmic effects
Curated Content: Needs Vetting Before Put to Clinical Use