Cholesterol lowering medication

I have been taking LIPITOR 20mg for over two years following by-pass surgery at Cleveland Clinic.  Recent test results were: Total 150; LDL 84; HDL 55.  My insurance drug provider, Merck-Medco, wants me to change to ZOCOR 20mg (a Merck product).  What would you recommend ?

[Cleveland Clinic, MD]

They are both in the same family of cholesterol lowering drugs - called "statins" and are usually equally effective.  You may however need to take a larger dosage of the Zocor to get the same lipid lower effects of the Lipitor.  Make sure your doctor is aware of teh substitution.