Cardiovascular drugs treat diseases of the heart and blood vessels, including heart attacks, angina, hypertension, arrhythmias, blood clots, and hyperlipidemias (such as high cholesterol). Many of these drugs fit into more than one category.
Antihypertensives lower blood pressure. Common classes include diuretics, beta-blockers, calcium channel blockers, ACE (angiotensin-converting enzyme) inhibitors, angiotensin II receptor blockers (ARBs), centrally acting antihypertensives, alpha blockers, aldosterone antagonists, renin inhibitors, and vasodilators. Many are also sold as combination products that include two (and sometimes three) medications.
Diuretics: Often called “water pills,” diuretics lower blood pressure by increasing the excretion of water and salt by the kidneys. Diuretics are grouped into classes based on how they work.
Thiazide diuretics are commonly used antihypertensives. Examples of thiazides (brand names in brackets) include hydrochlorothiazide (Microzide, Oretic, HydroDiuril), chlorothiazide (Diuril), chlorthalidone (Thalitone), indapamide (Coversyl), and metolazone (Mykrox).
Loop diuretics act on the loop of Henle in the kidney. Examples of loop diuretics are furosemide (Lasix), torsemide (Soaanz, Demadex), bumetanide (Bumex), and ethacrynic acid (Edecrin).
Potassium sparing diuretics are another class of diuretics and include spironolactone (Aldactone, Carospir), triamterene (Dyrenium), amiloride (Midamor), and eplerenone (Inspra).
Diuretics may cause side effects such as increased urination and electrolyte imbalances, especially hypokalemia and calcium imbalances. They may precipitate gout by increasing serum uric acid levels. Potassium sparing diuretics may cause hyperkalemia (high blood potassium levels), which can lead to cardiac arrest in severe cases. Because of these risks, it’s important to monitor serum electrolyte levels after starting diuretic therapy. Loop diuretics and thiazides contain a sulfa group and should be avoided in patients with sulfa allergies.
Beta blockers: Beta blockers block beta receptors in the heart and blood vessels. This relaxes blood vessels and decreases cardiac output by slowing heart rate and reducing the force of contraction, which lowers blood pressure. Beta blockers have the generic name stem -olol. Commonly used beta blockers include metoprolol (Lopressor, Toprol XL), nebivolol (Bystolic), propranolol (Inderal), acebutolol (Sectral), atenolol (Tenormin), and carvedilol (Coreg).
Adverse effects include dizziness, bradycardia, fatigue, and constipation. Beta blockers may precipitate asthma attacks in patients with asthma. They may also mask symptoms of low blood sugar, so they should be used with caution in patients with diabetes. Suddenly stopping beta blockers may cause a dangerous increase in blood pressure.
Calcium channel blockers: Calcium channel blockers block calcium channels in the heart and/or blood vessels. This slows cardiac contraction and dilates blood vessels, lowering blood pressure. Some are commonly used as antihypertensives. Examples include amlodipine (Katerzia, Norliqva, Norvasc), nifedipine (Procardia, Adalat CC), diltiazem (Cardizem, Tiazac), and verapamil (Verelan, Calan).
Adverse effects include dizziness, headache, edema, bradycardia, constipation, and reflex tachycardia.
ACE (angiotensin-converting enzyme) inhibitors: ACE inhibitors block angiotensin-converting enzyme (ACE), which catalyzes the conversion of angiotensin I to angiotensin II. Angiotensin II increases blood pressure. By reducing angiotensin II levels, ACE inhibitors help lower blood pressure and dilate arteries and veins. ACE inhibitors have the generic name stem -pril.
Common examples include lisinopril (Carace, Zestril, Zestoretic, Prinivil), ramipril (Lopace, Triapin, Tritace, Altace), benazepril (Lotensin), captopril (Acepril, Capozide, Capoten, Acezide), enalapril (Innovace, Innozide, Vasotec, Epaned), trandolapril (Mavik, Tarka, Gopten), and perindopril (Coversyl, Aceon).
Adverse effects include dry cough, hyperkalemia, headache, and angioedema. The dry cough associated with ACE inhibitors is due to increased levels of bradykinin.
Angiotensin II receptor blockers (ARBs): ARBs block angiotensin II receptors (AT I receptors) in blood vessels and the heart. This blocks the action of angiotensin II and lowers blood pressure. Unlike ACE inhibitors, ARBs do not precipitate cough. ARBs have the generic name stem -sartan.
Common ARBs include losartan (Cozaar), valsartan (Diovan), telmisartan (Micardis), irbesartan (Avapro), candesartan (Atacand), olmesartan (Benicar), and azilsartan (Edarbi).
Adverse effects include hyperkalemia, dizziness, and angioedema.
Centrally acting antihypertensives: This group lowers blood pressure by reducing sympathetic nervous system outflow from the medulla (a region in the brain that includes control centers for autonomic functions). These drugs activate alpha 2 receptors in the medulla, which inhibits sympathetic signals to the cardiovascular system.
Examples include clonidine (Catapres, Kapvay), methyldopa (Aldomet), and guanfacine (Intuniv).
Adverse effects include edema, sedation, dry mouth, depression, bradycardia, orthostatic hypotension, impotence, constipation, gastric upset, and rebound hypertension with sudden discontinuation. Methyldopa is used as an antihypertensive in pregnant patients.
Alpha blockers: Alpha blockers dilate arteries and veins by blocking alpha 1 receptors on blood vessels. Examples include prazosin (Minipress), terazosin (Hytrin), and doxazosin (Cardura).
Adverse effects include dizziness, orthostatic hypotension, nasal congestion, headache, reflex tachycardia, and fluid retention. Alpha blockers are also used to treat benign prostatic hyperplasia.
Aldosterone antagonists: Aldosterone antagonists are a subtype of potassium sparing diuretics that also block the aldosterone receptor. Aldosterone is a hormone that increases blood pressure. These drugs are used to treat hypertension, heart failure, certain kidney disorders, and hormonal imbalances.
Examples include spironolactone (Aldactone, Carospir), eplerenone (Inspra), and finerenone (Kerendia).
Adverse effects include dizziness, hyperkalemia, muscle cramps, cough, upset stomach, breast tenderness, gynecomastia, and erectile dysfunction. Compared with older aldosterone antagonists such as spironolactone, newer drugs such as eplerenone and finerenone have a lower risk of erectile dysfunction and gynecomastia.
Renin inhibitors: Renin inhibitors block the renal enzyme renin, which catalyzes the conversion of angiotensinogen to angiotensin I. This reduces angiotensin I levels and leads to dilation of arteries and veins.
Adverse effects include diarrhea, cough, angioedema, and hyperkalemia. Renin inhibitors are contraindicated in pregnancy. Aliskiren (Tekturna) is available in the United States.
Vasodilators: Vasodilators dilate blood vessels by relaxing smooth muscle in the vessel wall. Some are used as antihypertensives, and they may also be used to treat angina and heart failure. Some preferentially dilate arteries, while others preferentially dilate veins.
Examples include hydralazine (Apresoline), minoxidil (Loniten), and nitrates such as nitroglycerine (Nitrostat) and nitroprusside (Nipride RTU, Nitropress). Drugs in other groups can also have vasodilating properties, including calcium channel blockers, ARBs, ACE inhibitors, and some beta blockers such as nebivolol and carvedilol.
Hydralazine, minoxidil, sodium nitroprusside, and nitroglycerine are also known as direct vasodilators because they dilate arteries and arterioles and significantly reduce vascular resistance. Nitrates preferentially dilate veins by releasing nitric oxide, which dilates blood vessels. Minoxidil opens potassium channels on smooth muscle cells in blood vessels, causing dilation.
Adverse effects of vasodilators include reflex tachycardia, headache, and edema. Cyanide toxicity may occur with nitroprusside due to metabolic breakdown of the drug. Tolerance may develop with long-term nitrate use. Nitrates are contraindicated with sildenafil (Viagra) and other drugs in the same class, such as tadalafil (Cialis) and vardenafil (Levitra). Using hydralazine for more than three months has been associated with a lupus-like syndrome with joint pain, arthritis, rash, and systemic effects. Minoxidil promotes hair growth and is used to treat baldness.
Combination antihypertensives: Many antihypertensives are used as combinations of two or three drugs in the same pill. Combination pills can improve adherence, reduce adverse effects, and may lower treatment costs. Common combinations include a diuretic with an ACE inhibitor/angiotensin receptor blocker/beta blocker/another diuretic, a renin inhibitor with a calcium channel blocker, or a calcium channel blocker plus an ACE inhibitor/angiotensin receptor blocker.
Commonly used examples include the following:
Amlodipine plus benazepril (Lotrel)
Amlodipine plus perindopril (Prestalia)
Amlodipine plus olmesartan (Azor)
Benazepril plus hydrochlorothiazide (Lotensin HCT)
Enalapril plus hydrochlorothiazide (Vaseretic)
Candesartan plus hydrochlorothiazide (Atacand HCT)
Losartan plus hydrochlorothiazide (Hyzaar)
Olmesartan plus hydrochlorothiazide (Benicar HCT)
Metoprolol plus hydrochlorothiazide (Lopressor HCT)
Valsartan plus hydrochlorothiazide (Diovan HCT)
Telmisartan plus hydrochlorothiazide (Micardis HCT)
Hydrochlorothiazide and triamterene (Dyazide; Maxzide)
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