Amiodarone works in a similar way to sotalol by blocking potassium channels and slowing conduction within the heart.
This drug has been shown to be very effective at maintaining sinus rhythm and we would consider using this medication for patients with structural heart disease or for patients where other medications have failed to control their AF.
Despite being a powerful and effective drug in restoring and maintaining the normal heart rhythm, it is associated with many side effects and, therefore, we may only want to use the medicine for a short duration.
Depending on the severity of your symptoms we may decide to start this medicine either orally or by an intravenous infusion over 24 hours.
Because of the structure of amiodarone it takes a long time (weeks to months) for levels of the drug to build up in the body. You will usually be asked to take a 200mg tablet three times a day for one week, then twice a day for one week and then once a day thereafter.
Although generally well tolerated, amiodarone can cause the following side effects:
When taking amiodarone the skin can take on a greyish / blue tinge when your skin comes into contact with sunlight. Your skin may also become more sensitive to sunburn. Wearing sunblock and hats will help to prevent this. As amiodarone remains in the body for a long time it may be necessary to continue using sun block for a few months after stopping it.
The thyroid gland produces a hormone, which controls the body’s metabolism. Amiodarone can affect this gland making it both overactive (this occurs in about 2 per cent of people taking amiodarone) or under active (this occurs in about 6 per cent of people taking amiodarone). Your doctor will take regular blood tests to check if either of these has developed.
If you experience symptoms of extreme tiredness or restlessness, you should contact your GP to discuss this further. Your doctor will arrange for you to have blood tests if these have not already been done. Both an underactive and an overactive thyroid can be treated with medications. If you develop an overactive thyroid it is likely that we will need to stop the amiodarone.
Small deposits can form on the cornea of the eye (the clear surface that covers the pupil, iris and white of the eye). These deposits are not harmful, but you may notice the effects when looking at bright lights at night time e.g. when driving a car. Around one in 10 people taking amiodarone will notice a bluish halo around their vision. Again, this is not harmful.
Amiodarone can cause problems with thickening (fibrosis) of the lungs, which may be irreversible. The risk of this occurring increases if you have been on the medication for a long time. If you experience shortness of breath, you should arrange to see your GP as soon as possible.
Amiodarone causes problems with the function of the liver in rare cases. Your doctor will perform regular blood tests to check that your liver function is normal. If you experience jaundice (yellowing of the skin) or new nausea and vomiting, you should arrange to see your GP as soon as possible.
Other side effects
You may notice that when you are first started on amiodarone it causes some gastrointestinal disturbances, such as nausea and vomiting. This should settle within a few days, but if you continue to have problems, you should contact your GP. It is also not unusual for people to get taste disturbances and a metallic taste in the mouth. Again, if this is causing you concern, you should see your GP.
When you are first started on amiodarone you will have a blood test performed to check your liver and thyroid function. You will also have a chest X-ray if you have not had one recently. Your GP will then recheck your liver and thyroid function every six months.
Amiodarone can interact with many medications and herbal medicines. Therefore, it is very important that your GP and pharmacist are aware of all the medicines you are taking (including herbal products).
We may recommend that your statin dose and digoxin is reduced and, if you are taking warfarin, the addition of amiodarone will cause your INR to increase and your warfarin dose will need to be reduced accordingly.
If you notice any of the following you should contact your GP as soon as possible:
- Any difficulties breathing, or if you develop an unexplained cough.
- Extreme tiredness or restlessness.
- Jaundice (any yellowing of your skin or the whites of your eyes). These could be signs of a problem developing in your liver.
- A severe skin rash. This could be a sign of an allergic reaction.