Combine it with niacin, and you'll reduce your risk by more than 50%.
40 mg is not high, it's the norm. Dosage of Simvastatin ca be as high as 80 mg. I am curious why you are on a statin with a total cholesterol of 160. What s your breakdown by LDL & HDL and do you have any risk factors of CAD currently? Plus, if your script was for 20 mg I would question the pharmacy about receiving 40 mg.
Let us know when you can and we can speak more accurately about your dosage.
Jon