In the armamentarium for rhythm control,
amiodarone has been a mainstay of
therapy for the management of
atrial fibrillation (AF). Although
amiodarone has shown to be effective in maintaining sinus rhythm, it has many extracardiac adverse effects.
Dronedarone, a
benzofuran amiodarone derivative, is structurally modified to reduce toxicities often associated with chronic
amiodarone therapy. With the addition of a methylsulfonyl group,
dronedarone is less lipophilic, has lower tissue accumulation, and a much shorter serum half-life of 24 hours compared with
amiodarone.
Dronedarone is also designed without the
iodine moieties that are responsible for thyroid dysfunctions associated with
amiodarone. Similar to
amiodarone,
dronedarone exhibits electrophysiologic characteristics of all 4 Vaughan Williams classifications. Phase III clinical trials have shown
dronedarone to be effective at reducing ventricular rate, reducing recurrence of AF, and reducing cardiovascular morbidity and mortality in patients with AF or
atrial flutter (AFL). However,
dronedarone was associated with increased mortality in one study that included patients with severe
heart failure (HL) and
left ventricular dysfunction. Overall,
dronedarone appears to be well tolerated. The most common side effects are gastrointestinal in nature and include
nausea,
vomiting, and
diarrhea. Because of its more favorable adverse effect profile,
dronedarone is likely to be a useful addition to the therapeutic management of AF. However, further comparative studies with
amiodarone are needed to define
dronedarone's place in
therapy more clearly.