Class III antiarrhythmic agent that is indicated for acute cardioconversion of atrial fibrillation and atrial flutter of a recent onset to sinus rhythm.

Induces a slow inward sodium current, which prolongs action potential and refractory period of myocardial cells.

There should not be concomitant administration of Class Ia and Class III agents.

Trade name Corvert.

Rapid conversion of acute atrial fibrillation or atrial flutter (typically of less than 90 days duration) to normal sinus rhythm.

It is generally more effective for treating atrial fibrillation than atrial flutter.

Pretreatment before electrical cardioversion or administration post-cardioversion to prevent recurrence.

It primarily acts by blocking the rapid component of delayed rectifier potassium (K⁺) channels in cardiac tissue.

It prolongs phase 3 of the cardiac action potential and increases the effective refractory period of atrial and ventricular myocytes. It also induces a slow inward sodium current that aids in rhythm control.

Dosing and Administration

Route: Intravenous (IV) infusion only, given in a hospital or supervised clinical setting.

Strength: Available as a 1 mg/10 mL IV solution.

Standard Dosing:

Weight ≥ 60 kg: 1 mg administered intravenously over 10 minutes. If the arrhythmia does not terminate, a second 1 mg dose may be given over 10 minutes.

Weight < 60 kg: 0.01 mg/kg administered intravenously over 10 minutes, which may be repeated once if needed.

Infusion Rule: The infusion is stopped immediately if the arrhythmia resolves or if new-onset ventricular tachycardia develops.

Major Side Effects and Risks

Torsasdes de Pointes / QT Prolongation: Like other Class III agents, ibutilide prolongs the QT/QTc interval, carrying a risk of polymorphic ventricular tachycardia (torsades de pointes).

Mitigating Risk: Pre-treating or co-administering intravenous magnesium (typically 1 to 2 grams) can help reduce the incidence of torsades de pointes.

Monitoring: Patients must remain on continuous electrocardiographic (ECG/telemetry) monitoring for atleast 4 hours after the infusion or until the QTc interval returns to baseline.

Common Mild Side Effects: Headache, nausea, and mild pain or irritation at the injection site.

Contraindications and Precautions

Avoid Concomitant Class Ia or III Agents: Should not be given alongside other Class Ia or Class III antiarrhythmics due to additive risks of excessive QT prolongation. (A washout period of at least 5 half-lives is typically required for prior antiarrhythmics).

Electrolytes: Potassium and magnesium levels should be corrected and verified within normal ranges prior to and during treatment.

Results in successful heart rhythm control in 31-44% of patients within 90 minutes, with sustained polymorphic ventricular tachycardia in 0.9-2.5% of patients.

Results in atrial flutter are better than for atrial fibrillation.

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