Two common classes of blood pressure medications – angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) – are equally effective at controlling high blood pressure, according to a report released today by the Agency for Healthcare Research and Quality, part of the U.S. Department of Health and Human Services.

The report, which analyzed published results from 61 studies, also found that ACEIs are slightly more likely than ARBs to cause a harmless but persistent dry cough. A summary of the report will be posted on-line in the Annals of Internal Medicine.

Authors of the report also said that more research is needed to learn how ACEIs and ARBs may differ when it comes to longer term benefits and harms. In particular, more information is needed about how the medications may differ in decreasing the risks of heart attack, stroke, or death.

“An enormous number of Americans have high blood pressure, and we need to provide them with the best information possible about their medications’ potential benefits and harms,” said AHRQ Director Carolyn M. Clancy, M.D. “This report summarizes the current scientific evidence on these medications and helps set the agenda for needed research.”

Blood pressure is the force of blood pushing against artery walls. The cause of high blood pressure (140/90 mmHg or higher) is often unknown. Systolic pressure measures pressure during a heartbeat. Diastolic pressure measures pressure between beats. Because it typically has no symptoms, high blood pressure – also known as hypertension – is often called “the silent killer.”

More than 65 million American adults – about one-third of the adult population – have high blood pressure. If left untreated, high blood pressure can cause catastrophic health problems: the heart may enlarge, which can lead to heart failure; small bulges – aneurysms – may form in blood vessels, including the aorta (the main artery to the heart) and others in the brain, legs, and intestines; blood vessels in the kidney may narrow, causing kidney failure; blood vessels in the eyes may burst or bleed, possibly leading to blindness; and arteries throughout the body may “harden” faster, potentially leading to heart attack or stroke.

The AHRQ-funded study, completed by the Agency’s Duke University Evidence-based Practice Center in Durham, N.C., compared both the benefits and harms of ACEIs and ARBs. Both classes of drugs control blood pressure effectively by targeting a key hormone that helps regulate blood pressure. The AHRQ-funded study did not include other blood pressure treatments such as diuretics or beta blockers.

The ACEIs included in the AHRQ analysis were benazepril (sold as Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik). The ARBs included were candesartan cilexetil (Atacand), eprosartan (Teveten), irbesartan (Avapro), losartan (Cozaar), olmesartan medoxomil (Benicar), telmisartan (Micardis), and valsartan (Diovan).

Among the report’s conclusions:

• ACEIs and ARBs are equally effective at controlling blood pressure. This conclusion is based on studies that included 16,597 patients who were followed for periods from 12 weeks to 5 years.

• In studies of patients in everyday clinical settings, a dry cough was reported by about 1.7 percent of patients who took ACEIs and about 0.6 percent who took ARBs. Patients who took ACEIs in clinical trials were slightly more likely than patients who took ARBs to withdraw from the studies.

• It is unknown whether ACEIs and ARBs differ when it comes to long-term benefits and risks. Among available studies, there are not enough cases of death or stroke to make conclusions. More research is needed.

• There are no consistently apparent differences between ACEIs and ARBs when it comes to impacting blood fats known as lipids, managing or slowing the progression of diabetes, controlling renal disease, or impacting heart function.

• More research is needed to compare the drugs’ benefits and harms for hypertension patients who have additional health problems, such as diabetes, congestive heart failure, chronic kidney disease, and dyslipidemia (an imbalance in lipid/cholesterol metabolism). Future studies should include more patients who are older and from ethnic and racial minorities.

The new report, Comparative Effectiveness of Angiotensin-Converting Enzyme Inhibitors (ACEIs) and Angiotensin II Receptor Antagonists (ARBs) for Treating Essential Hypertension, is the newest analysis from AHRQ’s Effective Health Care program. That program is an ongoing federal effort to compare alternative treatments for significant health conditions and make the findings public. The program helps patients, doctors, nurses, and others choose the most effective treatments.

Source: Agency for Healthcare Research and Quality (AHRQ)