Hypertension remains poorly controlled in the United States, even with many options for antihypertensive treatment. Data from the 1994 U.S. National Health and Nutrition Examination Study (NHANES) III suggest that, compared with data obtained in 1991, patients are less aware of hypertension and that fewer than one third of patients with hypertension have adequately controlled disease. Other studies linking the incidence of heart attack and high blood pressure indicate that systolic blood pressures between 120 and 160 mm Hg and diastolic pressures between 70 and 99 mm Hg were common in patients who had had a heart attack. Low drug efficacy and poor patient compliance contribute to inadequate control of hypertension. Angiotensin II receptor antagonists are promising medications. Neutel reviewed the safety and efficacy of this class of drugs.
Angiotensin II receptor antagonists are well tolerated and have an adverse event rate similar to, or better than, placebo. Evaluating the efficacy of these agents requires direct comparison with other antihypertensive medications. One representative of this class of drugs, telmisartan, lowered diastolic and systolic blood pressures more than the angiotensin-converting enzyme (ACE) inhibitor enalapril. Telmisartan and lisinopril, another ACE inhibitor, were shown to be equally effective. Reductions in blood pressure were also similar with telmisartan and amlodipine.
A number of important pharmacologic differences exist among the angiotensin II receptor antagonists. Although telmisartan and losartan effectively lowered blood pressure, telmisartan showed a statistically greater reduction in mean 24-hour blood pressure and also in systolic and diastolic pressures during the 18 to 24 hours after drug administration. This apparent difference in therapeutic half-life may be significant in maintaining medication effect throughout the entire day.
The author concludes that the excellent side-effect profile and the documented efficacy of the angiotensin II receptor antagonists make them an appropriate first-line choice in decreasing blood pressure. The 24-hour efficacy, as measured by ambulatory blood pressure monitoring, shows continued effectiveness, providing good coverage during the early morning hours when patients are more likely to have an acute cardiac event.
editor's note: Specific angiotensin II receptor antagonists appear to have fewer associated adverse effects than ACE inhibitors. The incidence of cough and angioedema is significantly lower, although a few episodes of angioedema have been documented with these medications. Hyperkalemia remains a potential complication, especially when this class of antihypertensives is used in combination with potassium-sparing diuretics such as spironolactone or triamterene. Angiotensin II receptor antagonists should be used with caution in patients with liver or kidney failure. The indication for this drug class remains treatment of hypertension only, with therapeutic efficacy in congestive heart failure and left ventricular hypertrophy remaining to be documented.—r.s.