Saturday, August 09, 2008

Beware of the Simvastatin/Amiodarone Drug Interaction

For electrophysiologists, the drug combinations of amiodarone (marketed as Cordarone® or Pacerone®) and simvastatin (marketed as Zocor®) is a common drug combination. The FDA issued an alert that these two drugs, when taken together, might result in an increased incidence of rhabdomyolysis (injury to muscle cells characterized by muscle aches, weakness and dark urine). It is thought by some that this might result from competition of the two drugs for the same metabolic pathway in the liver:
Statins such as atorvastatin (Lipitor®), lovastatin (Mevacor®) and simvastatin (Zocor®)are metabolised via a cytochrome P450 3A-dependent pathway while fluvastatin (Lescol®), pravastatin (Pravachol®)and rosuvastatin (Crestor®) are metabolised via cytochrome P450 3A-independent pathways. As simvastatin and amiodarone are metabolised by the same isoenzyme, in the present case, the concomitant use of these drugs may have resulted in competition, resulting in excess of free plasma statin and thereby causing myotoxicity. However, there are limited publications on this interaction and the exact mechanism has not been established.
It is recommended to keep the daily simvastatin dose to 20 mg or less to avoid this side effect of the drug combination.


h/t: WSJ.


Anonymous said...

Hey Wes

Nice comments.

I found this through a google search of crestor and amio

John Mandrola

Anonymous said...

My name is Wendy Rosko and i would like to show you my personal experience with Zocor.

I am 60 years old. Have been on Zocor for 8 days now. MD stopped med when I reported muscle pain and sent me for a blood test to measure muscle inflamation. Off med for 2 days and still having muscle cramps in arms and legs. No generalized aching.

I have experienced some of these side effects -
had leg cramps which I didn't realize were a side effect. On day 8 I woke up feeling as if I had the flu - bad muscle aches and cramps.

I hope this information will be useful to others,
Wendy Rosko