High blood pressure, or hypertension, is defined as a blood pressure reading of 140/90 mmHg or higher. Left unchecked, high blood pressure can damage the cardiovascular system and increase the risk of heart disease, stroke, kidney disease, peripheral vascular disease and blindness. Appropriate treatment, however, can help prevent these complications. Medications to treat high blood pressure are grouped into categories based on the method of action and include diuretics, beta blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers and vasodilators.
Diuretics
Diuretics are often used in combination therapy with other blood pressure medications and may be used alone to treat mild cases of high blood pressure. The prototypical diuretic is hydrochlorothiazide (HCT). HCT increases salt and water excretion in the kidneys, and lowers the volume of blood in the cardiovascular system.
Beta Blockers
Beta blockers decrease the force of heart contraction and lower the heart rate. According to a 2008 article in the Journal of the American College of Cardiology, these two actions reduce the pressure generated by the heart in the cardiovascular system. These medications are preferred in individuals with a history of heart disease or heart attack. Some examples of beta-blocker medications are carvedilol (Coreg), metoprolol (Lopressor) and atenolol (Tenormin). Side effects include impotence, fatigue and depression.
Angiotensin-Converting Enzyme (ACE) Inhibitors
ACE inhibitors relax blood vessels by blocking the enzyme that makes angiotensin II. Angiotensin II is a substance produced in the body that causes blood vessels to contract. By relaxing the blood vessels, ACE inhibitors reduce blood pressure. Some examples of ACE inhibitors are captopril (Capoten), enalapril (Vasotec) and lisinopril (Zestril). According to the Mayo Clinic, the most common side effect is dry cough. In individuals with kidney disease, ACE inhibitors may cause further reduction of kidney function and elevated blood potassium levels.
Angiotensin Receptor Blockers (ARBs)
ARBs are the newest class of blood pressure medications. They block receptors all over the body that would normally bind angiotensin II and cause blood vessels to contract. Some examples of ARBs are losartan (Cozaar), valsartan (Diovan) and irbesartan (Avapro). Side effects of ARBs are generally milder than those of ACE inhibitors.
Calcium Channel Blockers
Calcium channel blockers are an older class of blood pressure medication. They decrease the force of heart contraction and relax the muscle in the walls of the arteries. Some examples of calcium channel blockers are nifedipine (Procardia), diltiazem (Cardizem) and amlodipine (Norvasc). Side effects include fatigue, flushing, headache, constipation and ankle swelling.
Alpha Blockers
Alpha blockers are sometimes used in combination therapy with other medications. They work by reducing the overall excitability of the nervous system, and are rarely used as first-line treatment. However, because of some treatment overlap, they may be used in men who also suffer from an enlarged prostate. Examples of alpha blockers are terazosin (Hytrin) and doxazosin (Cardura). Side effects include dizziness, fatigue and visual problems.
Vasodilators
Vasodilators dilate (expand) the blood vessels to reduce the pressure created within the vessels of the cardiovascular system. They work by relaxing the muscles in the walls of the blood vessels and are rarely used as first-line treatment, except in emergency situations. In individuals with stabilized blood pressures, vasodilators are used in combination therapy with diuretics or beta blockers. Some examples of vasodilators are hydralazine (Apresoline), clonidine (Catapres) and nitroprusside (Nitropres). Side effects include angina (chest pain) and heart attack in patients with existing heart disease.
