High Blood Pressure Medication
There are a variety of medications used to treat high blood pressure. These drugs are called antihypertensive agents. Which agent a patient is started on depends on numerous factors, including ease of use, side effects, and coexisting medical conditions that might dictate preferential use of one agent over another.
Generally, an antihypertensive agent is started at a relatively low dose, and the response to it is assessed over the course of several weeks. If the blood pressure remains elevated, the dose of the medication is gradually increased.
When treatment with relatively high doses of an antihypertensive medication fails to lower blood pressure to target levels, two options are possible: (1) that particular medication may be discontinued and a different class of antihypertensive medication begun, or (2) a second class of medication may be added to the first agent. The second approach is often used because different classes of antihypertensive agents work in different ways to lower blood pressure, and the actions of one agent may complement the actions of the second agent. In some patients, it may be necessary to add a third agent.
Most of the newer blood pressure medications are taken once or twice a day. They all have side effects, but most are well tolerated by patients.
Diuretics ("water pills") increase the kidneys' excretion of salt (sodium) and water, decreasing the volume of fluid in the bloodstream and the pressure in the arteries. Diuretics are the oldest and most studied antihypertensive agents.
One of the most commonly used diuretic agents is hydrochlorothiazide (HydroDiuril®, Microzide®). Other diuretics used to treat hypertension include the following:
- Acetazolamide (Diamox®)
- Furosemide (Lasix®)
- Indapamide (Lozol®)
- Metolazone (Zaroxolyn®)
- Spirnolactone (Aldactone®)
- Torsemide (Demadex®)
- Triamterene (Dyrenium®)
Combination medications that contain both a diuretic and a different class of antihypertensive agent are being produced.
The main side effect of these agents is increased frequency of urination. Another side effect is increased urinary excretion of potassium. Because of this, doctors monitor blood potassium levels when initiating therapy and periodically thereafter. Patients who have low potassium levels are encouraged to eat foods rich in potassium, such as bananas, or may be prescribed a potassium supplement.
Aliskiren (Tekturna®) is a medication that can be used alone or in combination with other antihypertensive agents to treat high blood pressure. It is often used with diuretics and an angiotensin-receptor blocker (ARB). This medication should not be used during pregnancy.
In April 2012, the makers of Valturna®, a combination of aliskiren and valsartan approved in 2009, agreed to pull this drug from the U.S. market and the Food and Drug Administration (FDA) issued a warning against using medications containing aliskiren in patients with diabetes or kidney problems (renal impairment). This warning was issued in response to early clinical trial data indicating an increased risk for kidney damage, hypotension (very low blood pressure) and hyperkalemia (high potassium levels) in people with diabetes who take aliskiren combined with angiotensin converting enzyme inhibitors (ACE inhibitors) and angiotensin receptor blockers (ARBs) to treat high blood pressure. Talk to your doctor if you have been prescribed a blood pressure medication containing aliskiren.
Beta blockers decrease the vigor of the heart's contractions. By decreasing the force used to pump blood into the arteries, the medications decrease blood pressure. In addition to lowering blood pressure, beta blockers have multiple beneficial effects (including prolonged life) in patients with coronary artery disease, patients who have had myocardial infarction (heart attack), and many patients with congestive heart failure (CHF).
Commonly used beta blockers include the following:
- Atenolol (Tenormin®)
- Bisoprolol (Zebeta®)
- Carvedilol (Coreg®)
- Metoprolol (iLopressor®, Toprol SL®)
- Timolol (Blockadren®)
Another beta blocker, labetolol (Normodyne®, Trandate®) has alpha blocker properties that dilate the arteries and lower blood pressure.
Potential side effects of the beta blockers are slowing the heart rate excessively, worsening heart failure (careful long-term use has been shown to frequently provide beneficial effects in patients with CHF), and, rarely, contributing to confusion, depression, and impotence (erectile dysfunction).
Calcium channel blockers. This class of agents lowers blood pressure in several ways. Two of these agents, diltiazem (Cardizem®) and verapamil (Calan®, Covera HS®, Isoptin®, Veralan®) act in part like the beta blockers, decreasing the vigor of the heart's contractions. They decrease blood pressure by decreasing the force with which blood is pumped into the arteries. These agents also dilate (open up) arteries, decreasing resistance to blood flow, thereby decreasing blood pressure.
The newer calcium channel blockers primarily dilate the arteries and have little effect on the forcefulness of the heart's contractions. These include:
- Amlodipine (Norvasc®)
- Felodipine (Plendil®)
- Idradipine (DynaCirc®)
- Nicardipine (Cardene®)
- Nisoldipine (Sular®)
Norvasc® has been combined with the cholesterol-lowering drug Lipitor® to treat patients with high blood pressure and high cholesterol. This combination drug, which is called Caduet®, offers the convenience of taking only one medication to control both conditions.
Calcium channel blockers may have serious side effects and should be used with caution in patients with pulmonary arterial hypertension (PAH). PAH, which is life-threatening, is high blood pressure in the arteries that supply blood to the lungs (the pulmonary arteries).
In some cases, diltiazem and verapamil, which decrease the force of the heart's contractions, worsen congestive heart failure symptoms. Verapamil may occasionally cause constipation, especially in elderly patients. Many of the calcium channel blockers cause headache and edema (swelling) in the ankles and feet.
ACE inhibitors. These medications help dilate the arteries, thereby decreasing resistance to blood flow and consequently decreasing blood pressure. They have many other beneficial effects and are used to treat patients with congestive heart failure. Many studies have shown that treatment of heart failure patients with ACE inhibitors improves heart failure symptoms, decreases the chance of future hospitalizations, decreases the risk for future heart attack, and decreases the risk of death from heart failure.
There are many ACE inhibitors available, including the following:
- Benazepril (Lotensin®)
- Captopril (Capoten®)
- Enalapril (Vasotec®)
- Fosinopril (Monopril®)
- Lisinopril (Prinivil®, Zestril®)
- Quinapril (Accupril®)
- Ramipril (Altace®)
- Trandolapril (Mavik®)
ACE inhibitors are usually tolerated well, but there are potential side effects. Approximately 10% of patients develop a chronic nonproductive cough. Rarely, ACE inhibitors produce a sudden swelling of the lips, face, and cheek areas in an allergic reaction that can occur at any time during therapy. If an allergic reaction occurs, medical attention should be sought immediately. Because ACE inhibitors can affect kidney function and raise the potassium level, doctors monitor these during the first several weeks of therapy and periodically thereafter.
Angiotensin-receptor blockers (ARBs). This class of medications are similar in some respects to ACE inhibitors. Like ACE inhibitors, they help dilate arteries, lowering blood pressure and making it easier for the heart to pump blood throughout the body. Also, like ACE inhibitors, they can improve congestive heart failure symptoms, decrease the chances of future hospitalizations for heart failure, and prolong life. Ongoing studies are comparing the effects of ARBs with the ACE inhibitors and are investigating the use of both in patients with heart failure.
Currently available ARBs include:
- Azilsartan medoxomil (Edarbi™)
- Candesartan (Atacand®)
- Irbesartan (Avapro®)
- Losartan (Cozaar®)
- Telmisartan (Micardis®)
- Valsartan (Diovan®)
ARBs are generally taken once a day and do not commonly produce significant side effects. Rarely, they interfere with or worsen kidney function.
In April 2012, a combination of aliskiren and valsartan (called Valturna®), which had been approved by the FDA in September 2009 to treat high blood pressure in some patients, was pulled from the U.S. market by the manufacturers. If you are taking this medication, contact your physician.
Direct-acting vasodilators. The medication hydralazine more or less directly dilates the arteries in the body, lowering blood pressure. Hydralazine is sometimes used in combination with isosorbide dinitrate to treat patients with congestive heart failure.
Centrally acting agents. These antihypertensive agents affect the central nervous system (brain) to decrease blood pressure. Such medications include clonidine (Catapres®) and methyldopa (Aldomet®). Because these drugs act directly on the brain, they occasionally cause drowsiness, depression, and other symptoms.