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Pharmacy and Medications

Lipitor and zocor dosage comparison

04/26/2006

Question:

I recently wanted to switch my mecication from 10 mg lipitor to zocor for insurance coverage reasons. My doctor prescribed 40mg of zocor which is the middle strength of that drug. My cholesteral levels have been constant on 10 mg lipitor for years. Years ago I was on the lowest dose of zocor (10mg) and switched to lipitor for some reason. I could not get a clear answer as to why the doctor is prescribing such a strong (40mg) dose. I`m thinking of switching doctors because of this. Any thoughts as to why he`s prescribing 40mg zocor if my cholesteral has been stable for so long? Is zocor 1/4 the strength of lipitor?

Answer:

To compare milligram strengths of different medications is like comparing apples to oranges. Each medication has a unique chemical makeup that makes it different from other medications. The strength required to get an effect would differ as well, such that medications within the same class of drug may have very different dosage strengths available. In order to more correctly compare one drug to another you would need to look at the action of a medication to exert an effect on the body.

For example, with cholesterol lowering medications such as simvastatin (Zocor) and atorvastatin (Lipitor), the LDL or "bad cholesterol" lowering ability is often used for comparison purposes. Studies have shown that 10mg. atorvastatin will lower the LDL by 27-39% when taken correctly. A comparable dose of simvastatin would be either 20mg. with a 30% reduction or 40mg. with a 38% LDL reduction. Changing from atorvastatin 10mg. to simvastatin 40mg seems very reasonable. You would have to ask your physician for specific reasons as to why he or she chose this dose.

Submitted by Erin Shupert, PharmD candidate, University of Cincinnati

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Response by:

University of Cincinnati Jan Scaglione, BS MT, PharmD ,DABAT
Assistant Professor of Pharmacy Practice
Drug and Poison Information Center
Cincinnati Children’s Hospital Medical Center
University of Cincinnati