What is Amiodarone?
Amiodarone is an anti-arrhythmic medication which aids patients suffering from life-threatening ventricular and supraventricular rhythm disorders. This medication is applied in the case of ventricular tachycardia or ventricular fibrillation. Although amiodarone was discovered in 1961, it wasn't approved for medical applications till 1985, in the United States. This delay in approval is testament to the fact that amiodarone is the strangest anti-arrythmic drug ever developed even though it is the most effective. Amiodarone is an excellent drug to tackle persistent atrial fibrillation.
How does amiodarone work?
Medically, amiodarone falls under the category of a class III anti-arrythmic agent, which aids to prolong phase 3 of the cardiac action potential. Amiodarone displays properties similar to a beta blocker or potassium channel blocker acting on the SA and AV nodes. This consequently increases the refractory period via sodium and potassium-channel effects, thus slowing the intra-cardiac conduction of the cardiac action potential. Additional effects of the medication occurs similar to class Ia, II and IV anti-arrhythmic agents. The patients being treated with this medication should be aware of all the risks associated with this highly effective drug.
Features of amiodarone
- It takes several weeks for the drug to achieve maximum effectiveness. This happens due to the fact that amiodarone is stored in most of the tissues in the body and the tissues need to be saturated to equip the body with the drug. The typical regimen for equipping a patient with amiodarone is by using very large doses for a fortnight, and then tapering the dosage for over a month.
Amiodarone exits the body at an exceedingly slow rate. This is because the drug is not removed through excretion, but it is only purged when amiodarone-containing cells are lost, through shedding such as with skin cells or cells from the gastro-intestinal tract. Even though a patient might have chosen to stop amiodarone, the drug continues to remain inside the body for months. The 'half-life' of this drug is measured in weeks compared to hours as in the case of other drugs.
Since amiodarone gets stored in all kinds of human tissues, the emergent side-effects may affect various organs. To make matters worse, the side-effects may take a long time (months or years) to develop.
Side-Effects of Amiodarone
As per the guidelines brought forth by the European Society of Cardiology and the American College of Cardiology, following side-effects have to be accounted for:
- Administering amiodarone may lead to hyperthyreosis, due to the presence of Iodine in the drug. The drug should not be given to a patient suffering from hyperthyreosis.
Sometimes the drug causes skin problems resulting in pigmentation (by overexposure to the sun bringing about a phototoxic reaction) that usually wears off after the drug leaves the system.
Rarely it can lead to pulmonary fibrosis.
It has also been known to affect the cornea of the eye.
When to take Amiodarone?
It is an excellent drug for patients suffering from ventricular and supraventricular arrhythmias. Amiodarone has varying side-effects that may or may not be fatal, and the patient receives the first few doses in the hospital to detect any adverse reaction. The drug should not be given to a patient who is allergic to amiodarone or iodine. Other scenarios to forego this medication includes certain heart conditions such as the 'AV block' (unless the patient is already fitted with a pacemaker). The drug is also not administered to a patient with an history of slow heart beats which would otherwise cause the patient to faint.
If you suffer from asthma, liver disease, vision problems, high/low blood pressure, thyroid disorder, an electrolyte imbalance or if you have a pacemaker or defibrillator implanted in the chest, please bring your condition to the physician's notice before taking amiodarone.
Note: Clinical trials have shown amiodarone to have positive evidence of risk when administered to pregnant women. The drug can pass into breast milk and may harm the baby while nursing.