Amiodarone

Brand names

• Alti-Amiodarone
• Braxan
• Cordarone
• Gen-Amiodarone
• Med-Amiodarone
• Novo-Amiodarone
• Pacerone
• PMS-Amiodarone

Usage

To prevent and treat heartbeat irregularities, including atrial fibrillation and ventricular tachycardia. The relative risks of using this medicament must be weighed carefully against its benefits, since amiodarone can be toxic, especially when taken at high doses or for long periods of time.

How it works

Amiodarone slows and helps regulate nerve impulses in the heart, and acts directly on the tissue of the heart, making heart muscle less responsive to abnormal stimuli.

Side effects

Serious

Cough, shortness of breath, increased palpitations, loss of voice (rare). Nausea, vomiting, and yellow-tinged skin or eyes (jaundice) may occur as an indication of serious liver problems.

Common

Stomach upset; nausea; vomiting; constipation; loss of appetite; low-grade fever; heightened skin sensitivity to sun, resulting in greater predisposition to sunburn; numbness or tingling in the fingers or toes; trembling or shaking; unsteadiness when walking; headache.

Less common

Bitter or metallic taste in the mouth, blue-gray discoloration of skin, vision disturbances, dry eyes, dry, puffy skin, coldness or chills, dizziness, nervousness or restlessness, diminished sex drive in males, scrotal pain and swelling, slow heartbeat, unusual or profuse sweating, insomnia, fatigue, unexpected gain or loss of weight.

Possible interactions

Other medicaments:

Amiodarone may increase the effects of:

• antihypertensive medicaments and cause excessive lowering of blood pressure.
• atropinelike medicaments.
• cyclosporine (Sandimmune, others) may lead to cyclosporine toxicity if cyclosporine doses are not lowered.
• digoxin (Lanoxin) by increasing blood level.
• procainamide (Procan SR, others) and NAPA.
• warfarin (Coumadin, etc.); check INR (prothrombin times) more often, and adjust dosing.

Amiodarone taken concurrently with:



• amprenavir (Agenerase), indinavir (Crixivan), ritonavir (Norvir) and perhaps other protease inhibitors may increase amiodarone blood levels and lead to toxicity.
• beta blockers may result in abnormally low heart rates or sinus arrest. Extreme caution is advised.
• calcium channel blockers should be avoided in patients with partial block (A V) or sick sinus syndrome.
• cimetidine (Tagamet) can increase amiodarone levels.
• cisapride (Propulsid) may lead to serious heart rhythm problems.
• clonazepam (Klonopin) caused clonazepam toxicity in one case report. Caution is advised.
• digoxin (Lanoxin) can cause digoxin toxicity.
• disopyramide (Norpace) can prolong QT interval and lead to abnormal heart rhythms.
• dofetilide (Tikosyn) can lead to heart toxicity.
• dolasetron (Anzemet) can lead to heart toxicity.
• fentanyl (Actiq, Duragesic) may lead to low blood pressure, slow heart rate and lowered ability of the heart to work (cardiac output).
• flecainide (Tambocor) may allow lower flecainide dose to get the same effect.
• gatifloxacin (Tequin) may result in abnormal QT intervals and lead to abnormal heart rhythms.
• halofantrene (Halfan) can lead to heart toxicity.
• insulin or oral antidiabetic medicaments may result in blunted blood sugar benefits.
• lidocaine (various) may lead to lidocaine toxicity. Extreme caution is advised.
• methotrexate (Rheumatrex, others) increases risk of methotrexate toxicity. Extreme caution is advised.
• mexiletine (Mexitil) may result in abnormal heart beats. Caution is advised.
• moxifloxacin (Avelox) may result in abnormal heart beats.
• nelfinavir (Viracept) may result in amiodarone toxicity.
• phenytoin (Dilantin) or phosphenytoin (Cerebyx) can result in phenytoin, phosphenytoin and amiodarone toxicity.
• propafenone (Rythmol) may lead to propafenone toxicity. Reduced propafenone doses may be needed.
• quinidine can cause increases in quinidine levels.
• sparfloxacin (Zagam) may result in increased risk of abnormal heart rhythms.
• verapamil (Calan, others) can precipitate or worsen congestive heart failure.

The following medicaments may decrease the effects of amiodarone:



• cholestyramine (Questran, others) by increasing removal (enterohepatic elimination) of amiodarone.
• rifabutin (Mycobutin).
• rifampin (Rimactane, Rifadin).

Herbal medicines or minerals:

Using St. John's wort, ma huang, or kola while taking this medicine may result in unacceptable heart stimulation. Belladonna, henbane, Scopolia, pheasant's eye extract or lily-of-the-valley or Squill powdered extracts should not be taken if you have abnormal heart rhythms. Since St. John's wort and amiodarone may increase sun sensitivity, the combination is not advised. Pyridoxine may increase risk of phototoxicity.

Beverages:

Your doctor may ask you to restrict caffeine intake.

Alcohol:

Use caution. Alcohol can increase the blood-pressure-lowering effects and may have an undesirable effect on heart rhythm in high doses.

Tobacco smoking:

Nicotine can irritate the heart, reducing effectiveness.

Exposure to sun:

Use caution. This medicament causes photosensitization.

Exposure to heat:

Use caution. The use of this medicament in hot environments may increase the risk of heatstroke.

Occurrence of unrelated illness:

Vomiting, diarrhea or dehydration can affect this medicament's action adversely. Report such developments promptly.

Discontinuation:

This medicament should not be stopped abruptly after long-term use. Ask your doctor for help regarding gradual dose reduction.