Amiodarone Hydrochloride (Tablet)
Indications
Amiodarone is used for many serious
arrhythmias of the heart including ventricular fibrillation, ventricular
tachycardia, atrial fibrillation, and atrial flutter.
Pharmacology
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.
Interaction
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.
Contraindications
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.
Side Effects
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.
Therapeutic Class
Potassium channel blockers
Storage Conditions
Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.
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