A:

This is an interesting story of two similar drug families.

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are very effective drugs for controlling blood pressure.

Both drug types widen small arteries. They also reduce the amount of fluid that you hold in your bloodstream by blocking the production of the hormone angiotensin II. This makes them great drugs for treating high blood pressure. They are also able to improve heart failure symptoms, and have a protective effect on the kidneys in people with diabetes.

Both drug types reduce the activity of the hormone angiotensin II, but in slightly different ways. ACE inhibitors cause a slight change in another hormone-like substance at the same time. The level of "bradykinin" becomes slightly increased. This is probably why ACE inhibitors cause a dry cough in 5% to 20% of people who take them.

ACE inhibitors can also cause a rare but dangerous allergic reaction called angioedema. This is swelling of the mouth, tongue and throat.. The dry cough and angioedema are less likely to occur from ARB drugs compared with ACE inhibitors. If cough or allergy side effects do occur, they will go away after you stop taking an ACE inhibitor.

The other difference in these two drug groups is the cost. Most doctors recommend that you begin with an ACE inhibitor because it is the least expensive, and you can switch to an ARB drug if side effects appear.

Many health insurance plans require you to try an ACE-inhibitor first.

A few examples of ACE-inhibitors are:

• benazepril (Lotensin)
• captopril (Capoten)
• enalapril (Vasotec)
• lisinopril (Prinivil, Zestril)

Some examples of ARBs include:

• candesartan (Atacand)
• irbesartan (Avapro)
• losartan (Cozaar)
• valsartan (Diovan)