3 October 2012
Years ago someone produced a facetious (and fictional) history of a new drug. It went something like this.
1. New drug announced (“must try it” say all the whizz GP’s)
2. Drug cures everything (No 1 best seller)
3. Case of agranulocytosis (“should be banned”, sales plummet)
4. Drug finds true niche market
Poor simvastatin seems to follow that pathway almost exactly.
It seems a long way from the heady days of 1994 when the landmark 4S study found enormous health gains in people who had a myocardial infarction and were prescribed simvastatin.
In the early years of the next decade, the question of simvastatin causing myopathy and rhabdomylosis (a condition where damaged muscle is broken down) began to rear its head. Initially, it was thought to be quite rare. Then medical opinion thought that it occurred only when high doses of the drug (80mg a day) were used.
Then simvastatin was the first statin to come off patent. Costs fell and prescribing rocketed.
This year simvastatin received a double, and possibly final, whammy.
Firstly, the Medicines and Healthcare products Regulatory Agency changed the dosage recommendation when simvastatin is used with either diltiazem or amlodipine to a maximum of 20mg a day. They later added that its use was also contraindicated with ciclosporin, danazol or gemfibrozil. The reason for this is that these drugs increase the plasma concentration of simvastatin; making myopathy and rhabdomyolosis more common.
Secondly atorvastatin came off patent this year.
So, many GP’s will take the easy way out and, rather than puzzling over the various dose recommendations of simvastatin in various circumstances, simply switch their patients to atorvastatin.
Unfortunately, the beneficial effect of simvastatin appears to be a class effect (that is, it is seen with all statins) whereas the harmful effects seem to be specific to simvastatin.
Finally, please do NOT fall into the trap and stop prescribing statins altogether. Some consultants fell into this trap in the rosiglitazone/pioglitazone saga: with wonderfully muddled thinking, they suggested stopping pioglitazone because of problems with rosiglitazone.
The findings of 4S are still as relevant today as they were in 1994. The prescribing of a statin after a myocardial infarction reduces the risk of a further myocardial infarction by up to 30%. This reduction FAR OUTWEIGHS any potential harm that simvastatin may cause.