Saturday, 4 September 2010

MRCP revision battle 2.2: Amiodarone and dronedarone


Amiodarone is a dirty, dirty drug, and as well has being dirty has a long half life of between 26 and around 126 DAYS.

It has a whole host of side effects to look out for in MRCP questions/real life:
- torsade de pointes
- ataxia
- alveolitis
- pulmonary fibrosis
- corneal microdeposits
- hepatitis
- metallic taste
- photosensitivity
- grey skin
- peripheral neuropathy
- and the classical THYROID PROBLEMS - if hypothyroid, amiodarone can be continued, if hyper, in general it should be stopped.

To try and remember this list I have a little mental cartoon of a man with a grey face, wearing sunglasses (photosensitivity) drinking from a metal can of beer (metallic taste and hepatits) and staggering because of his ataxia and peripheral neuropathy. He also has a goitre (thyroid problems) and is coughing (pulmonary fibrosis/alveolitis).  Due to the amiodarone prolonging his QT he goes into torsades and arrests; he then sees halos and glare (due to either him dying or his corneal microdeposits, depending on my mood)

The onset of amio is in hrs IV or 1-3 weeks when given orally.
As a practical aside remember when giving IV it is given in 5% dextrose and the doses tend to be 300mg over 20mins then 900mg over 24 hrs.

As an MRCP-irrelevant but randomly interesting aside DRONEDARONE has been proposed as a less toxic alternative to amiodarone ... essentially amiodarones brother but without his dirtiness.  Trials such as ADONIS and ATHENA (don't you just love drug companies acronyms?  yet another of my secret fetishes) showed that dronedarone did not cause thyroid problems or fibrosis.  Unfortunately, the ANDROMEDA trial showed it was dangerous in heart failure, and overall while amiodarone is 50-60% successful in treating AF dronedarone is only 30-40% successful.  So, since it costs more and works less, NICE have said no.