Drug information of Ibutilide

Mechanism of effect

Ibutilide Fumarate Injection prolongs action potential duration in isolated adult cardiac myocytes and increases both atrial and ventricular refractoriness in vivo. Voltage clamp studies indicate that Ibutilide Fumarate Injection, at nanomolar concentrations, delays repolarization by activation of a slow, inward current (predominantly sodium), rather than by blocking outward potassium currents, which is the mechanism by which most other class III antiarrhythmics act.

These effects lead to prolongation of atrial and ventricular action potential duration and refractoriness, the predominant electrophysiologic properties of Ibutilide Fumarate Injection in humans that are thought to be the basis for its antiarrhythmic effect.

Pharmacodynamic

Ibutilide prolongs the action potential duration and increases both atrial and ventricular refractoriness in vivo. Voltage clamp studies indicate that ibutilide, at nanomolar concentrations, delays repolarization by activation of a slow, inward current (predominantly sodium), rather than by blocking outward potassium currents, which is the mechanism by which most other class III antiarrhythmics act.

Pharmacokinetics

• Half-Life: 2-12 hr
• Onset: 90 min following infusion
• Duration: 24 hr
• Protein Bound: 40%
• Vd: 11 L/kg
• Metabolism: Liver via oxidation
• Excretion: Urine (82%); feces (20%)

Dosage

Injectable solution

0.1mg/mL

Atrial Fibrillation/Flutter

<60 kg: 0.01 mg/kg (0.1 mL/kg) IV infusion repeat after 10 minutes PRN 

>60 kg: 1 mg (one vial) IV infusion, repeat after 10 minutes PRN

Renal Impairment

Dose adjustment not necessary

Hepatic Impairment

Dose adjustment not necessary

Drug contraindications

hypersensitivity to this drug

Side effects

Headache , nausea , palpitations , renal failure , cardiac failure

Interactions

Fluphenazine , Ranolazine , Dolasetron , Palonosetron , vandetanib , Droperidol , sparfloxacin , Procainamide , Mefloquine , Amiodarone , Bisacodyl , Flecainide , Dofetilide , Goserelin , Promazine , Vasopressin , Arsenic trioxide , Halofantrine , Grepafloxacin , Terfenadine , Asenapine , Alfuzosin , Paliperidone , Perflutren , Pimavanserin , Entrectinib , Bretylium , gilteritinib , glasdegib , Eliglustat , Bepridil , bedaquiline , Dasatinib , Gemtuzumab , vemurafenib , Halaven

Amiodarone, dofetilide, bisacodyl, flecainide: Using this drugs together with ibutilide can increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. Patient may be more susceptible if he/she have congenital long QT syndrome, other cardiac diseases, conduction abnormalities, or electrolyte disturbances (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting).
Procainamide: Using procainamide and ibutilide is not recommended. Taking these drugs together can cause pain or discomfort in chest, shortness of breath, unusual heartbeats, or feeling dizzy or lightheaded.

Alerts

Antiarrhythmics

Class Ia antiarrhythmic drugs, such as disopyramide, quinidine, and procainamide, and other class III drugs, such as amiodarone and sotalol, should not be given concomitantly with Ibutilide Fumarate Injection or within 4 hours postinfusion because of their potential to prolong refractoriness. In the clinical trials, class I or other class III antiarrhythmic agents were withheld for at least 5 half-lives prior to ibutilide infusion and for 4 hours after dosing, but thereafter were allowed at the physician's discretion.

Other drugs that prolong the QT interval

The potential for proarrhythmia may increase with the administration of Ibutilide Fumarate Injection to patients who are being treated with drugs that prolong the QT interval, such as phenothiazines, tricyclic antidepressants, tetracyclic antidepressants, and certain antihistamine drugs (H1 receptor antagonists).

Heart block

Of the nine (1.5%) ibutilide-treated patients with reports of reversible heart block, five had first degree, three had second degree, and one had complete heart block.

Points of recommendation

Ibutilide can cause life-threatening irregular heart rhythms. Patient heart rate will be constantly monitored using an electrocardiograph or ECG (sometimes called an EKG).

Pregnancy level

C

Related drugs

dronedarone , Amiodarone , Sotalol , Dofetilide , Bretylium , Vernakalant