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Don't Take High Dose Simvastatin!

Posted Jun 08 2011 5:00pm
Today the FDA just announced a new warning on the highest dose of simvastatin, the most popular cholesterol medication prescription in the country.  They have issued this warning because "the highest approved dose--80 milligram (mg)--has been associated with an elevated risk of muscle injury or myopathy, particularly during the first 12 months of use."
The current recommendation is not to start simvastatin at 80mg and only to continue taking the 80mg if you "have been taking this dose for 12 months or more and have not experienced any muscle toxicity. It should not be prescribed to new patients.

First, why is this announcement so important.
As Forbes' Matthew Herper points out in A Snapshot Of The Cholesterol Drug Market , though Lipitor is the biggest selling drug in terms of dollars, generic simvastatin is actually the most commonly prescribed cholesterol lowering  medication.  As you can see from the graph below (viewed much better on the Forbes site), once Zocor became available as generic simvastatin, it became the most popular statin written (blue line) whereas Lipitor (red line) prescriptions continue to tumble. Over time, insurance companies have made it more and more difficult to write for any branded statin by increasing co-pays for patients or increasing hurdles to get prescriptions approved.

In fact, simvastatin makes sense for many patients.  Most data suggest that benefit is derived from statins when they reach about a 30% reduction in bad cholesterol, or LDL.  The folks at the NIH's NHLBI have evaluated the efficacy of all the available statins (see below) and you can see that most statins will achieve that goal at various doses.  For example 10mg of atorvastatin (Lipitor), 20-40mg of simvastatin, and 5mg of rosuvastatin (Crestor) all lower LDL cholesterol by about the same amount.  Thus, if you just need a 30% reduction in LDL, you should be fine with the generic.  Problem is that many patients need more than that amount of reduction.  Thus, if you want to stick to a generic, you would have to go to 80mg of simvastatin.

Now one might thing that the stronger, more potent the statin, the more likely it is to cause side effects.  Turns out the opposite is true.  The graph below shows that when plotting LDL reduction against number of patients developing myopathy (what the FDA is concerned about), it seems like the more potent statins (Crestor, Lipitor) not only lower cholesterol better, but have a lower risk of myopathy. Myopathy is pretty uncommon, usually only about 1/10,000 or 0.01%. Looking at both Lipitor and Crestor, you can see as the dose goes up (10, 20, 40, 80) the percent of reduction of LDL continues to improve, but rate of myopathy is pretty much the same except for a slight bump at the 80mg dose of Lipitor.  (Though not on the graph, you can see why the 80 mg dose of Crestor wasn't approved, because at that dose there was significant myopathy). However, when you jump from 40-80 mg of simvastatin, the LDL only goes up a few points, but the rate of myopathy skyrockets to over 1% (that's 1/100 instead of 1/10,000).  Finally, you can why cerivastatin or Baycol was pulled from the market.  It was pretty weak at lowering LDL, but had up to 2% incidence of myopathy at the higher doses.

The good news is that Lipitor will go generic in only a few months.  When that happens, I am sure that the graph above will change drastically.  All Lipitor scripts will likely go to the generic medication and probably many of the simvastatin prescriptions will also switch to generic atorvastin, since it is a better statin (more potent, fewer side effects).  Crestor is another option (most effective, fewest side effects), but will not go generic for a while. The other thing to note is that Pfizer, who is about to lose Lipitor, is trying to get as much business as it can by offering patient coupons, so that (as long as you are not on Medicare part D or Medicaid) a prescription of Lipitor will only cost you $4 until it goes generic. 

Bottom Line: All statins are not created equal and generic is not always best.  If you are on Simvastatin 80mg, you should seriously discuss with your doctor about switching.  In fact, if you are on simvastatin at any dose and not on Medicare part D or Medicaid, but have commercial insurance, you should consider asking your doctor about switching to Lipitor with the $4 coupon (you may actually save money by NOT taking the generic) until it too goes generic.
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