Although it is a common belief that all antihypertensive agents are equally effective
in reducing blood pressure, there is some evidence to the contrary, both in the general
population and when specific patient demographics are considered. In black patients,
β blockers and angiotensin-converting enzyme (ACE) inhibitors have been shown to be
less effective at reducing blood pressure than the thiazide diuretics. After age 60,
the percentage of responders to β blockers is less than with calcium antagonists,
and a higher percentage of elderly patients also achieve normotensive blood pressure
levels with diuretic therapy than with β blockers. When a thiazide diuretic is added
to an ACE inhibitor, β blocker or calcium antagonist, the number of normotensive responders
increases significantly. Combinations of some other agents (i.e., an ACE inhibitor
plus a β blocker) may not, however, improve efficacy.
Diuretics, β blockers and ACE inhibitors are all generally well tolerated, with a
9 to 10% incidence of subjective side effects. The use of calcium antagonists and
especially the centrally acting adrenergic inhibitors may result in more frequent
Data from long-term, diuretic-based clinical trials do not support the statement that
diuretic therapy results in sustained elevations in lipid levels. These trials have
shown cholesterol levels to be at or below baseline after long-term diuretic therapy.
The use of β blockers, on the other hand, may result in long-term elevation of triglyceride
levels and a slight decrease in high-density lipoprotein cholesterol. Calcium antagonists
and ACE inhibitors do not affect lipid levels, and α blockers may actually lower cholesterol
levels and increase high-density lipoprotein levels.
Whereas some studies have demonstrated a link between diuretic-induced hypokalemia
and increased ventricular ectopy, other studies have not. It appears prudent, however,
while awaiting additional data, to prevent hypokalemia from developing in those patients
at high risk for arrhythmias and heart disease. In such cases, the use of a potassium-sparing
diuretic combination is probably preferable to the use of potassium supplements.