| Class Ia: Action: Sodium channel blockers: Depress phase 0 depolarization; slow conduction; prolong repolarization. |
| Indications: Supraventricular tachycardia, ventricular tachycardia, symptomatic ventricular premature beats. |
| Disopyramide | | Immediate release: 100–200 mg every 6 h Sustained release: 200–400 mg every 12 h | 2–8 mg/mL | Renal | Urinary retention, dry mouth, markedly ↓ LVF, QT prolongation |
| Procainamide | Loading: 10–17 mg/kg at 20–50 mg/min Maintenance: 1–4 mg/min | 50 mg/kg/day in divided doses every 4 h (short-acting) | 4–10 mg/mL; NAPA (active metabolite), 10–20 mcg/mL | Renal | |
| Quinidine | 6–10 mg/kg (intramuscularly or intravenously) over 20 min (rarely used parenterally) | 324–648 mg every 8 h | 2–5 mg/mL | Hepatic | GI, ↓ LVF, ↑ Dig |
| Class Ib: Action: Shorten repolarization. |
| Indications: Ventricular tachycardia, prevention of ventricular fibrillation, symptomatic ventricular premature beats. |
| Lidocaine | Loading: 1 mg/kg; Maintenance: 1–4 mg/min | | 1–5 mg/mL | Hepatic | CNS, GI, ↓ LVF |
| Mexiletine | | 100–300 mg every 8–12 h; maximum: 1200 mg/day | 0.5–2 mg/mL | Hepatic | CNS, GI, leukopenia |
| Class Ic: Action: Depress phase 0 repolarization; slow conduction. (Propafenone is a weak calcium channel blocker and beta-blocker and prolongs action potential and refractoriness.) |
| Indications: Ventricular tachycardia (in the absence of structural heart disease), refractory supraventricular tachycardia. |
| Flecainide | | 50–150 mg twice daily | 0.2–1 mg/mL | Hepatic | CNS, GI, AFL with 1:1 conduction, ventricular pro-arrhythmia |
| Propafenone | | 150–300 mg every 8–12 h | Note: Active metabolites | Hepatic | CNS, GI, AFL with 1:1 conduction, ventricular pro-arrhythmia |
| Class II: Action: Beta-blockers, slow AV conduction. |
| Indications: Supraventricular tachycardia, ventricular tachycardia, symptomatic ventricular premature beats, long QT syndrome. |
| Esmolol | Loading: 500 mcg/kg over 1–2 min Maintenance: 50 mcg/kg/min | Other beta-blockers may be used concomitantly | Not established | Hepatic | ↓ LVF, bradycardia, AV block |
| Metoprolol | 5 mg every 5 min up to 3 doses | 25–200 mg daily | Not established | Hepatic | ↓ LVF, bradycardia, AV block, fatigue |
| Propranolol | 1–3 mg every 5 min up to total of 5 mg | 40–320 mg in 1–4 doses daily (depending on preparation) | Not established | Hepatic | ↓ LVF, bradycardia, AV block, bronchospasm |
| Class III: Action: Prolong action potential. |
| Indications: Amiodarone: refractory ventricular tachycardia, supraventricular tachycardia, prevention of ventricular tachycardia, atrial fibrillation, ventricular fibrillation; Dofetilide: atrial fibrillation and flutter; Dronedarone: atrial fibrillation (not persistent); Ibutilide: conversion of atrial fibrillation and flutter; Sotalol: ventricular tachycardia, atrial fibrillation. |
| Amiodarone | 150–300 mg infused rapidly, followed by 1 mg/min infusion for 6 h and then 0.5 mg/min for 18 h | 800–1600 mg/day for 7–14 days; maintain at 100–400 mg/day | 1–5 mg/mL | Hepatic | Pulmonary fibrosis, hypothyroidism, hyperthyroidism, photosensitivity, corneal and skin deposits, hepatitis, ↑ Dig, neurotoxicity, GI |
| Dofetilide | | 125–500 mcg every 12 h | | Renal (dose must be reduced with kidney dysfunction) | Torsades de pointes in 3%; interaction with cytochrome P-450 inhibitors |
| Dronedarone | | 400 mg twice daily | | Hepatic (contraindicated in severe impairment) | QTc prolongation, HF. Contraindicated in HF (NYHA class IV or recent decompensation), persistent AF |
| Ibutilide | 1 mg over 10 min, followed by a second infusion of 0.5–1 mg over 10 min | | | Hepatic and renal | Torsades de pointes in up to 5% of patients within 3 h after administration; patients must be monitored with defibrillator nearby |
| Sotalol | 75 mg every 12 h | 80–160 mg every 12 h (maximum 320 mg daily) | | Renal (dosing interval should be extended if creatinine clearance is < 60 mL/min) | Early incidence of torsades de pointes, ↓ LVF, bradycardia, fatigue (and otherside effects associated with beta-blockers) |
| Class IV: Action: Slow calcium channel blockers. |
| Indications: Supraventricular tachycardia, ventricular tachycardia (outflow tract, idiopathic). |
| Diltiazem | 0.25 mg/kg over 2 min; second 0.35-mg/kg bolus after 15 min if response is inadequate; infusion rate, 5–15 mg/h | 120–360 mg daily in 1–3 doses depending on preparation | | Hepatic metabolism, renal excretion | Hypotension, ↓ LVF, bradycardia |
| Verapamil | 2.5 mg bolus followed by additional boluses of 2.5–5 mg every 1–3 min; total 20 mg over 20 min; maintain at 5 mg/kg/min | 80–120 mg every 6–8 h; 240–480 mg once daily with sustained-release preparation | 0.1–0.15 mg/mL | Hepatic | Hypotension, ↓ LVF, constipation, ↑ Dig |
| Miscellaneous: Indications: Supraventricular tachycardia. |
| Adenosine | 6 mg rapidly followed by 12 mg after 1–2 min if needed; use half these doses if administered via central line | | | Adenosine receptor stimulation, metabolized in blood | Transient flushing, dyspnea, chest pain, AV block, sinus bradycardia; effect ↓ by theophylline, ↑ by dipyridamole |
| Digoxin | 0.5 mg over 20 min followed by increment of 0.25 or 0.125 mg to 1–1.5 mg over 24 h | 1–1.5 mg over 24–36 h in 3 or 4 doses; maintenance, 0.125–0.5 mg/day | 0.7–2 mg/mL | Renal | AV block, arrhythmias, GI, visual changes |
| Ivabradine | | 5–7.5 mg every 12 h | | Renal and fecal | Bradycardia, phosphenes (visual brightness) |