Richard Hoffmann, Ask the Pharmacist, 07/12/11

Q: Are water pills useful for high blood pressure?

A: Yes, they are; and this subject has been recently reviewed in a Johns Hopkins Health Alert (www.johnshopkinshealthalerts.com, 2011).

Very few medicines have been studied as intently or used as successfully for as many years as diuretics. Whether they are taken alone or in combination with other hypertension drugs, diuretics have consistently been shown to be safe, effective and relatively inexpensive.

Often referred to as fluid or water pills, diuretics help reduce blood pressure by increasing the removal of sodium and fluid from the blood into the urine by the kidneys. Probably more important, some diuretics also lower blood pressure by promoting dilation of small blood vessels. There are three types of diuretics and each one acts on a different site in the kidney.

+ Thiazide diuretics — These are the most commonly used diuretics. Examples include hydrochlorothiazide and chlorthalidone.

+ Loop diuretics — These diuretics, such as furosemide (Lasix), are more powerful for salt and water excretion than thiazides and are often used in people with heart failure or kidney disease. 

+ Potassium-sparing diuretics — These medications may be used in combination with a thiazide diuretic to counteract potassium loss. Some examples are triamterene (Dyrenium), spironolactone (Aldactone) and eplerenone (Inspra).

Despite their declining popularity over the years, diuretics have been vindicated by recent studies showing this class of drugs is not only as effective as other hypertension drugs but may, in fact, provide better protection from cardiovascular disease, heart failure, stroke and other complications.

The seminal study to reassert the effectiveness of diuretics was the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), which followed about 33,000 people with hypertension who had at least one other risk factor for heart disease (for example, type 2 diabetes or smoking).

Participants were randomly assigned to receive the thiazide diuretic chlorthalidone or one of two newer drugs — the ACE inhibitor lisinopril (Prinivil, Zestril) or the calcium channel blocker amlodipine (Norvasc).

Chlorthalidone was found to be superior to the ACE inhibitor in terms of lowering risk of stroke, heart failure and angina (chest pain), and more effective at preventing heart failure than the calcium channel blocker.

Several studies in the past few years have re-examined the ALLHAT data and come to similarly positive conclusions. Nevertheless, thiazide diuretics are not always the choice drugs for everyone. A beta-blocker may be the preferred option for someone with coronary artery disease and an ACE inhibitor may be the first choice for a person with kidney disease.

High blood pressure or hypertension is a very common problem that affects about 50 million people in the U.S. and nearly one-third of them don’t know they have it.

While high blood pressure produces few symptoms, if it is not corrected it can lead to a stroke, heart attack or heart disease. It is often referred to as the “silent killer.”

Many people are concerned about high cholesterol levels, but high blood pressure is an even greater cause for concern.

In most cases, the cause of high blood pressure is unknown. The regulation of blood pressure is very complex and a number of body systems are involved, including the nervous system, the kidneys, blood vessels, the heart and various enzymes or hormones.

Richard P. Hoffmann, PharmD, has been a pharmacist for more than 40 years. Send questions to him at 2960 E. Coventry Court, Hernando, FL 34442.