Encainide

Administration

• Type: Class IC antiarrhythmic (sodium channel blocker)
• Dosage Forms: Capsules (25mg or 35mg)
• Routes of Administration: PO
• Common Trade Names: Enkaid

Adult Dosing

Sustained ventricular tachycardia

• 25mg PO t.i.d
  • May be increased to 35mg PO t.i.d after 3-5 days

Pediatric Dosing

• Safety and effectiveness in pediatrics not established

Special Populations

Pregnancy Rating

• Category B

Lactation risk

• Unknown risk to nursing infants

Renal Dosing

• Adult: Reduce to single initial daily 25mg dose; increase to 25mg b.i.d after 7 days if needed.
• Pediatric: N/A

Hepatic Dosing

• Adult: No adjustments needed, but use caution when increasing dosage
• Pediatric: N/A

Contraindications

• Allergy to class/drug
• Preexisting 2nd or 3rd-degree AV block
• Preexisting right bundle branch block w/ left hemiblock
• Presence of cardiogenic shock

Adverse Reactions

Serious

• Provocation or aggravation of ventricular arrhythmias
• 2nd or 3rd-degree AV block
• Sinus bradycardia

Common

• Dizziness
• Blurred/abnormal vision
• Headache

Pharmacology

• Half-life: Genetically determined; 1-2 hours for 90% of patients; 6-11 hours for 10% of patients
• Metabolism: Hepatic; Encainide converts to two active metabolites (ODE and MODE)
• Excretion: Urine and feces
• Mechanism of action: Blocks sodium channels in purkinje fibers and myocardium; slows conduction, reduces membrane responsiveness, and inhibits automaticity