Medications can interfere with pressure

Q: If I am taking a beta blocker for heart disease, can I take an alpha-adrenergic blocker such as Flomax for prostate problems? Will this lower my blood pressure and pulse too much?

A: The answer is yes, you can take both, but you need to be especially cautious during the first week that you start the Flomax.

Alpha blockers cause relaxation of smooth muscle cells. For men with tight, smooth muscles around the prostate, taking an alpha blocker can help decrease symptoms such as frequent urination and a slow, weak stream. Alpha blockers also relax the smooth muscle cells that line the inside of our arteries. This action tends to lower blood pressure.

The older alpha blockers such as terazosin (Hytrin) and prazosin were not as specific for the prostate as the newer ones. Tamsulosin (Flomax) and alfuzosin (Uroxatral) have more action in and around the prostate and don't cause as much artery relaxation as the older drugs.

If a man is already taking any medication that tends to lower blood pressure, adding an alpha blocker, even one of the newer more specific ones, can cause a dramatic drop in blood pressure. This is especially true with the first few doses of the alpha blocker.

Most often, there won't be any significant blood pressure fall when the man is lying down. With standing, however, blood pressure can drop so much that it can cause dizziness, and rarely, a man can even pass out.

For this reason, I advise taking the alpha blocker at night, even if you don't take any other medications. Start with a low dose and be careful if you need to get up during the night. Sit on the side of the bed for a couple of minutes first.

Most men can gradually increase the dose of alpha blocker as long as there is no dizziness with standing. If blood pressure is already on the low side and the man is taking other medications, his doctor may advise him to temporarily decrease the dose of one or more of the blood pressure pills. When a beta blocker is used for heart disease, your doctor may not be able to reduce the dose of the beta blocker.

You may be able to try Flomax or Uroxatral, but consider first taking one-half of the usual starting dose.

Another strategy for men with symptoms of an enlarged prostate is to combine a low-dose Flomax or Uroxatral with a medication that helps shrink the prostate gland.

Finasteride (Proscar) and dutasteride (Avodart) don't affect blood pressure.

Howard LeWine, M.D., is a member of the Harvard Medical School faculty and practicing internist with Harvard Vanguard Medical Associates and Brigham and Women's Hospital, Boston, Mass. He serves as Chief Medical Editor of Internet Publishing at Harvard Health Publications. The Medicine Cabinet is distributed by Tribune Media Services Inc. and published Tuesdays in the TimesDaily. For additional consumer health information, visit health.harvard.edu.