Amiodarone Pharmacology


About Amiodarone
Class III Antiarrhythmic Agent.
Mechanism of Action of Amiodarone
It is a long acting class-3 antiarrhythmic drug. The drug exerts it`s action by: - 1) Blocks myocardial potassium channels and thus prolongs action potential duration and reduces nonuniformity of refractoriness among different fibres. 2) Preferentially blocks inactivated Na+ channels with relatively rapid rate of channel recovery; more effective in depressing conduction in cells that are partially depolarized or have longer action potential duration. 3) Inhibits Ca2+ channels of myocardium. 4) Blocking beta adrenergic receptors noncompetitively.
It prolongs action potential duration effective refractory period so that conduction is slowed and ectopic automaticity is markedly depressed but only slight effect on SA node. When used I.V. causes myocardial depression and hypotension.
Pharmacokinets of Amiodarone
Absorption: absorbed incompleately and slowly after oral administration. Distribution: Distributed widely in a protein bound form preferably in to highly perfused organs and accumulates in skeletal muscles and adipose tissue. Metabolism: Metabolized in liver in to active metabolite desethyl-Amiodarone. Excretion: Excreted mainly through bile.
Onset of Action for Amiodarone
Oral: 2days to 3 weeks,
I.V.: 1 to 5 minutes
Duration of Action for Amiodarone
Weeks to months
Half Life of Amiodarone
40 to 50 days
Side Effects of Amiodarone
4.Heart block
5.Heart failure
6.Sinus arrest
8.Corneal micro deposits
10.Visual disturbances
14.Abdominal pain
15.Hepatic impairment
16.Pulmonary fibrosis
19.Organizing pneumonia
21. Hypothyroidism and hyperthyroidism
Contra-indications of Amiodarone
1.Hypersensitivity to the drug
2.Second or third degree heart block
3.Congestive Heart failure
4.Cardiogenic shock
5.Severe bradycardia
6.Severe obstructive pulmonary diseases
7.Electrolyte imbalance
8.Severe Hypotension
9.Myasthenia gravis
10.Sinus node dysfunction
11.Atrial conduction defects
12.Thyroid diseases
Special Precautions while taking Amiodarone
Use with caution in following conditions:
1.Hepatic impairment
2.Renal impairment
3.Heart failure
4.In pacemaker patients
5.Monitor thyroid and liver function during therapy
6.Along with other anti arrhythmics, beta blockers, and calcium channel blockers
7.Along with antivirals like Ritonavir is contraindicated and use with caution along with Amprenavir.
Pregnancy Related Information
Old Age Related Information
Use with caution.
Breast Feeding Related Information
Children Related Information
Use with caution
Indications for Amiodarone
1.Atrial flutter
2.Atrial fibrillation
3.Paroxysmal supra ventricular tachycardia
4.Arrhythmias with Wolff Parkinson White syndrome
5.Ventricular tachycardia
6.Recurrent ventricular fibrillation
7.Ventricular arrhythmia not responding to other treatment
8.Hypertrophic cardiomyopathy
Interactions for Amiodarone
Anticoagulants: Hypoprothrombinemic effect enhanced requiring 30% - 50% reduction in dose. Effect persists months after discontinuation of amiodarone.
Beta-Blockers & Calcium Channel Antagonists ( Verapamil & Diltiazem): Additive effect.
Digoxin, procainamide, Quindine, Theophyline: Increase in serum levels leading to enhanced activity of these drugs.
Hydantoins: Increase in serum levels of hydantoins with decrease in levels of amiodarone.
Typical Dosage for Amiodarone
0.2gm 8th hourly for one week; then 12th hourly for next week. Then reduce the dosage up to minimum effective dose.
Schedule of Amiodarone
Storage Requirements for Amiodarone
Store below 25 degree C. in a dry place and protects from light. Keep out of reach of children.
Effects of Missed Dosage of Amiodarone
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Amiodarone
Treatment is supportive and symptomatic. Monitor and support cardiovascular and respiratory functions with haemodynamic and ECG monitoring. Reverse hypotension using positive inotropic agents such as dopamine or dobutamine or vasopressors like phenylephrine or nor epinephrine. Restore heart rate with beta adrenergic agonist like isoproterinol or artificial pacing.

Home Delivery for Amiodarone in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including amiodarone.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for amiodarone and other medicines and health products. Home delivery services for amiodarone may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take amiodarone only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for amiodarone before they complete the sale. You can get this information while placing the order for amiodarone with the pharmacy.

Amiodarone is a generic medicine name and there are several brands available for it. Some of the brands for amiodarone might be better known than amiodarone itself. If the pharmacy that's willing to deliver medicines to your home doesn't have amiodarone in stock, you can ask for one of the branded alternatives for amiodarone.