Drug Classification & Information

Amiodarone is classified as an anti-arrhythmic medication (class III anti-arrhythmic).  It has efficacy against several types of arrhythmias but can cause significant side effects in veterinary patients.  This medication should only be prescribed under the guidance of a veterinary cardiologist.  This medication has a long half-life therefore effects can persist even after discontinuation.

Indications for Use

Amiodarone is prescribed to treat a variety of irregular heart rhythms (arrhythmias) including supraventricular and ventricular tachycardia.  It is also used in patients with atrial fibrillation prior to electrical cardioversion.  In rare cases, amiodarone can convert atrial fibrillation into sinus rhythm.

Potential Drug Interactions

Amiodarone can increase the blood levels of digoxin and may lead to digoxin toxicity when used in combination.  Caution when used with cisapride, some anti-fungals, some antibiotics (erythromycin, moxifloxacin) and ondansetron as may result in significant arrhythmias.  Caution with other anti-arrhythmics such as beta and calcium channel blockers as may result in bradycardias (slow heart rate).

Drug Side Effects

Side effects are commonly reported with this medication.  The most commonly noted is gastrointestinal upset including anorexia, vomiting and diarrhea.  May cause liver dysfunction (hepatopathy).  Can result in low white cell and platelet counts.  In humans, thyroid dysfunction and pulmonary fibrosis has been reported. 

Therapeutic Monitoring

Baseline bloodwork (CBC, chemistry, T4) is recommended prior to treatment, then in one month following initiation of treatment, then every 4 months.  If used to treat arrhythmias, periodic electrocardiograms (ECGs) and Holter monitors may be indicated.

Dosage Forms

Human: 100, 200 & 400 mg tablets.