Often, medical studies showing some benefit or risk of a single drug are understood to mean that this benefit or risk may or may not accrue to every other drug in its class.
As more study and research occurs, we are coming to realize that in some cases different drugs in the same class can vary significantly in terms of their effectiveness or safety.
For example, Avandia (a diabetes drug) was taken off the market by the FDA several years ago due to heart disease risks with the drug. Actos (in the same drug class) was not.
Just a few years ago, head-to-head tests showed that two of the SSRI's (serotonin-specific re-uptake inhibitors, commonly used in the treatment of depression and anxiety) were both more effective and lower in side-effects than the others. Those two are Zoloft/sertraline and Lexapro/escitalopram.
More recently, we find that while the statins are all effective in lowering cholesterol and preventing heart attacks and strokes, two of them are particularly lower in side-effects and drug reactions. These two are Pravachol/pravastatin and Zocor/simvastatin (in doses of 40 mg a day, or less).
On the positive side, the so-called ACE inhibitors (a class of blood pressure lowering drugs that are particularly beneficial in diabetics) are known to prevent heart attacks and strokes. Additionally, several are also seen to reduce your risk of memory loss and Alzheimer's dementia due to there ability to positively affect circulation in the brain. These are Altace/ramapril, Tarka/trandolapril, Capoten/captopril, fosinopril, and Zestril/lisinopril.
