Amiodarone is used for many serious arrhythmias of the heart including ventricular fibrillation, ventricular tachycardia, atrial fibrillation, and atrial flutter.
Potassium channel blockers
Amiodarone Hydrochloride is used to correct abnormal rhythms of the heart. Amiodarone is considered a "broad spectrum" antiarrhythmic medication. The most important electrical effects of the drug includes : a delay in the rate at which the heart’s electrical system "recharges" after the heart contracts (repolarisation); 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); and a slowing of conduction through various specialised electrical pathways (called accessory pathways). In addition to being an antiarrhythmic medication, Amiodarone also causes blood vessels to dilate. Because of this effect it also may be of benefit in patients with congestive heart failure. This effect can result in drop of blood pressure.
Dosage & Administration
The oral dose is 200 mg 3 times daily for 1 week reduced to 200 mg twice daily or the minimum required to control arrhythmia. Amiodarone is usually 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 should be taken with meals.
Amiodarone may interact with b blockers such as Atenolol, Propranolol, Metoprolol, or certain calcium channel blockers, such as Verapamil or Diltiazem, resulting in an excessively slow heart rate. Amiodarone increases the blood levels of Digoxin when the two drugs are given together. Flecainide blood concentrations increase by more than 50% with Amiodarone. Procainamide and Quinidine concentrations increase by 30-50% during the first week of Amiodarone therapy. Amiodarone also can interact with tricyclic antidepressants (TCA). Amiodarone interacts with Warfarin and increases the risk of bleeding. Amiodarone inhibits the metabolism of Dextromethorphan.
Amiodarone is contraindicated in patients with cardiogenic shock; severe sinus-node dysfunction, causing marked sinus bradycardia; second- or third degree atrioventricular block; and when episodes of bradycardia have caused syncope (except when used in conjunction with a pacemaker). Amiodarone is contraindicated in patients with a known hypersensitivity to the drug or to any of its components, including iodine.
The most severe side effects of Amiodarone therapy are related to the lungs. These reactions can be fatal. Patients should report any symptoms of cough, fever, or painful breathing. Although quite rare, fatal liver toxicity may occur with Amiodarone therapy. Reversible corneal microdeposits (sometimes with night glare), rarely impaired vision due to optic neuritis; peripheral neuropathy and myopathy (usually reversible on withdrawal); bradycardia and conduction disturbances; phototoxicity and rarely persistent skin discolouration; hypothyroidism, hyperthyroidism; raised serum transaminases; jaundice, hepatitis and cirrhosis are reported. Other rare complaints are nausea, vomiting, metallic taste, tremor, sweating, vertigo, headache, sleeplessness, fatigue, alopecia, benign raised intracranial pressure, ataxia, rashes, vasculitis, renal involvement, thrombocytopenia, haemolytic or aplastic anaemia. In some cases, dose of Amiodarone may be reduced. In other cases, Amiodarone therapy may need to be stopped.
Pregnancy & Lactation
In general, Amiodarone should not be administered during pregnancy because there have been reports of hypo or hyperthyroidism in infants from oral Amiodarone use during pregnancy. If Amiodarone use is considered essential, however, the patient should be warned of the risk to the foetus. The safe use of Amiodarone in lactating women has not been established.
Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.