Medications and Drugs
Pharmacy Author: Emmanuel Saltiel, PharmD, FASHP, FCCP
Pharmacy and Medical Editor: Jay W. Marks, MD
GENERIC NAME: amiodarone
BRAND NAME: Cordarone
DRUG CLASS AND MECHANISM: Amiodarone is used to correct abnormal rhythms of
the heart. (It is an antiarrhythmic medication.) Amiodarone was discovered in
1961 and approved by the FDA in December of 1985. Although amiodarone has many
side effects, some of which are severe and potentially fatal, it has been
successful in treating many arrhythmias where other antiarrhythmic drugs have
failed. Amiodarone is considered a "broad spectrum" antiarrhythmic medication,
that is, it has multiple and complex effects on the electrical activity of the
heart which is responsible for the heart's rhythm. Among its most important
electrical effects are:
- a delay in the rate at which the heart's electrical system "recharges"
after the heart contracts (repolarization);
- a prolongation in the electrical phase during which the heart's muscle
cells are electrically stimulated (action potential);
- a slowing of the speed of electrical conduction (how fast each individual
impulse is conducted through the heart's electrical system);
- a reduction in the rapidity of firing of the normal generator of
electrical impulses in the heart (the heart's pacemaker);
- a slowing of conduction through various specialized electrical pathways
(called accessory pathways) which can be responsible for arrhythmias.
In addition to being an antiarrhythmic medication, amiodarone also causes
blood vessels to dilate (enlarge). This effect can result in a
drop in blood pressure. Because of this effect, it also may be of benefit in patients with
congestive heart failure.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets (pink), round in shape: 200 mg.
STORAGE: Tablets should be kept at room temperature, less than 30°C (86°F).
PRESCRIBED FOR: Amiodarone is used for many serious arrhythmias of the heart
including ventricular fibrillation, ventricular tachycardia,
atrial
fibrillation, and atrial flutter.
DOSING: Amiodarone usually is given in several daily doses to minimize
stomach upset which is seen more frequently with higher doses. For this same
reason, it is also recommended that amiodarone be taken with meals.
DRUG INTERACTIONS: Amiodarone may interact with
beta-blockers such as
atenolol (Tenormin), propranolol (Inderal), metoprolol (Lopressor), or certain
calcium channel blockers, such as verapamil (Calan, Isoptin, Verelan, Covera-HS)
or diltiazem (Cardizem, Dilacor, Tiazac), resulting in an excessively slow heart
rate or a block in the conduction of the electrical impulse through the heart.
Amiodarone increases the blood levels of digoxin (Lanoxin) when the two drugs
are given together. It is recommended that the dose of digoxin be cut by 50%
when amiodarone therapy is started.
Flecainide (Tambocor) blood concentrations increase by more than 50% with
amiodarone. Procainamide (Procan-SR, Pronestyl) and quinidine (Quinidex,
Quinaglute) concentrations increase by 30%-50% during the first week of
amiodarone therapy. Additive electrical effects occurs with these combinations,
and worsening arrhythmias may occur as a result. Some experts recommend that the
doses of these other drugs be reduced when amiodarone is started.
Amiodarone can result in phenytoin (Dilantin) toxicity because it causes a
two- or three-fold increase in blood concentrations of phenytoin. Symptoms of
phenytoin toxicity including unsteady eye movement (temporary and reversible),
tiredness and unsteady gait.
Ritonavir (Norvir) can inhibit the enzyme that is responsible for the
metabolism of amiodarone. Although no clinical problems have been recognized as
a result of this interaction yet, it would be prudent to avoid this combination
for fear of the potential for amiodarone toxicity.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Drug Interactions - Learn about potential drug interactions you may be exposed to. Drug interactions can occur with prescription drugs, OTC medication, vitamins, herbs, and supplements.
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- Premature Ventricular Contractions (PVCs) - Premature ventricular contractions (PVCs) are caused by heart attack, high blood pressure, cardiomyopathy, heart valve disease, medications, and more.
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