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Medications to Treat Hypertension

Kristen L. Mauk, PhD RN CRRN-A APRN BC Nearly 65 million American adults, or one in three persons, have hypertension. Often called the "silent killer" because of the lack of early symptoms, high blood pressure contributed to the death of more than 52,600 people in 2003 (American Heart Association, 2005). The death rate for African Americans, both men and women, is significantly higher than for Caucasians. Hypertension also remains the number-one risk factor for stroke, a leading cause of death and disability throughout the world. Hypertension is defined by the American Heart Association as a blood pressure of 140/90 or higher. The vast majority of hypertension has no identifiable cause but is manageable by lifestyle changes and medications. The purpose of this article is to discuss the common medications used in treatment of hypertension. The most recent guidelines for treating hypertension provide four basic strategies to manage and prevent complications. First, identify prehypertenion and begin lifestyle changes early. Prehypertension is defined as a blood pressure of 130­139 mm Hg systolic and 80­89 mm Hg diastolic. Persons with prehypertension are more likely to become hypertensive than those with lower blood pressures. Second, even for patients over the age of 50, treat a systolic blood pressure over 140 mm Hg. Previous guidelines allowed older adults more flexibility in the systolic reading if the diastolic was within normal limits. New research suggests that deaths could be avoided by initiating treatment earlier. Third, the use of more than one medication is advisable. "Using more than one drug to treat most patients will be key to improving blood pressure control rates. Patients and physicians need to begin the drug treatment process with an open mind, using as much medication as necessary to achieve goal blood pressure" (Jones, 2003). A few significant classes of medications are commonly used in treatment of hypertension. These include diuretics, beta-blockers, ACE inhibitors, angiotensin II receptor blockers, calcium channel blockers, and central alpha agonists. Table 1 provides a summary of the common medications used under each class.

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Common Medications

Diuretics Diuretics help older adults decrease water and sodium retention. The rule for dosing in the elderly is start low and go slow. Diuretics have fewer adverse reactions for older adults and reduce both morbidity and mortality associated with poor circulation (Kennedy-Malone, Fletcher, & Plank, 2000). Hydrochlorthiazide 12.5­25 mg/day is a commonly prescribed treatment. Furosemide (Lasix) may be used for those with impaired renal function. Side effects from diuretics include weakness, leg cramps, fatigue, and dizziness. Potassium supplements may be needed. Nurses should educate patients to take diuretics in the morning, because an increase in urination is likely to occur. Beta-Blockers Beta-blockers reduce the heart rate and lower cardiac output. Medications such as atenolol (Tenormin) and metoprolol (Lopressor, Toprol XL) are common. They are the drug of choice for patients with a history of angina or heart attack, but are contraindicated in those with chronic obstructive pulmonary disease (COPD). Betablockers are often used in combination with thiazide diuretics, particularly with older adults. They may be manufactured in combination with diuretics in medications such as Inderide (propranolol and hydrochlorothiazide). When combined with calcium channel blockers, betablockers may cause bradycardia. Major side effects from beta-blockers include fatigue, decreased exercise tolerance, depression, impotence, glucose intolerance, and increased triglycerides (The Washington Manual: Geriatrics Subspecialty Consult, 2005). Nurses should caution patients to report a pulse slower than 60 beats per minute (unless otherwise directed by the physician) and never to abruptly discontinue these medications. In the hospital setting, monitor blood pressure and pulse prior to administering beta-blockers. Nurses should also be alert that beta-blockers can mask hypoglycemia in diabetics and exacerbate wheezing in those with asthma.

ACe Inhibitors Angiogenesis-converting enzyme (ACE) inhibitors decrease resistance of the blood vessels by interfering with the body's production of angiotensin (a vessel constrictor), lowering the levels of this chemical to allow the arteries to relax. ACE inhibitors are preferred for patients with heart failure and as a first-line treatment to reduce the risk of nephropathy for those with diabetes. Doses should be titrated slowly over a period of weeks. ACE inhibitors are also frequently used with diuretics or calcium channel blockers for combination therapy. Side effects to particularly note include renal function changes, electrolyte imbalance, cough, dizziness, weakness, and orthostatic hypotension. Angiotensin-II Receptor Antagonists Angiotensin-II receptor blockers (ARBs), or antagonists, block the effects of angiotensin, producing effects similar to the ACE inhibitors. The mechanism of action is slightly different, in that the effects of angiotensin are prevented from ever effecting the heart or blood vessels by blocking the A-II receptors, thereby prohibiting elevation of blood pressure. A-II receptor antagonists may also used in combination with diuretics for better blood pressure control. The side effects with these medications are fewer than for the other drug classes used to treat hypertension. The incidence of serious side effects is rare, and the dry cough seen with ACE inhibitors occurs significantly less with ARBs. Calcium Channel Blockers Calcium channel blockers (CCBs), also known as calcium antagonists, reduce heart rate and relax blood vessels by interfering with the movement of calcium in the heart and associated arteries. By blocking the entry of calcium into specific cells, calcium channel blockers dilate the arteries and thus decrease the workload on the heart. For this reason, they are also used to treat angina and some dysrhythmias. Common medications in this category include diltiazem (Cardizem), amlodipine (Norvasc), and verapamil (Calan). Side effects of CCBs are constipation, headache, nausea, rash, edema, drowsiness,

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dizziness, and hypotension. Educate patients to take these medications before meals and as ordered. Patients should also be encouraged to limit caffeine intake while taking CCBs to decrease the risk of adverse effects. Blood work should be monitored carefully for therapeutic levels. Because constipation may be a common side effect of certain CCBs, patients should eat a diet high in fiber and drink plenty of fluids. In addition to antihypertensive medication therapy, nurses can encourage persons to reduce their risk of hypertension through dietary changes including a lower sodium intake (a good guideline is less than one teaspoon per day or under 2,000 mg for those with heart failure), avoidance of excess alcohol and caffeine consumption, and weight loss if obese. Increasing regular exercise and avoiding smoking also decrease the risk of hypertension. Nurses should encourage persons to have their blood pressure checked regularly and more frequently as they get older. Early diagnosis and treatment of prehypertension can help persons avoid the morbidities and increased mortality associated with high blood pressure. Rehabilitation nurses can educate patients and the general public about the need for treatment and the variety of medications that are useful in managing hypertension. Incorporating blood pressure management into patient education about stroke risk reduction is important in all settings. By controlling high blood pressure early with lifestyle changes and medications, people can positively affect their own health and decrease the risk of stroke and heart disease associated with this silent killer. Kristen L. Mauk, PhD RN CRRN-A APRN BC, is an associate professor of nursing at Valparaiso University, Valparaiso, IN.

Table 1.Commonly Prescribed Medications to Treat Hypertension (American Heart Association, 2006) Diuretics

Amiloride (Midamor) Bumetanide (Bumex) Chlorothiazide (Diuril) Chlorthalidone (Hygroton) Furosemide (Lasix) Hydrochlorothiazide (Esidrix, Hydrodiuril) Indapamide (Lozol) Spironolactone (Aldactone) Beta-Blockers Acebutolol (Sectral) Atenolol (Tenormin) Betaxolol (Kerlone) Bisoprolol/hydrochlorothiazide (Ziac) Bisoprolol (Zebeta) Carteolol (Cartrol) Metoprolol (Lopressor, Toprol XL) Nadolol (Corgard) Propranolol (Inderal) Sotalol (Betapace) Timolol (Blocadren) ACE Inhibitors Benazepril (Lotensin) Captopril (Capoten) Enalapril (Vasotec) Fosinopril (Monopril) Lisinopril (Prinivil, Zestril) Moexipril (Univasc) Perindopril (Aceon) Quinapril (Accupril) Ramipril (Altace) Trandolapril (Mavik) AG-2 Receptor Agonists Candesartan (Atacand) Eprosartan (Teveten) Irbesartan (Avapro) Losartan (Cozaar) Telmisartan (Micardis) Valsartan (Diovan) Calcium Channel Blockers Amlodipine (Norvasc, Lotrel) Bepridil (Vascor) Diltiazem (Cardizem, Tiazac) Felodipine (Plendil) Nifedipine (Adalat, Procardia) Nimodipine (Nimotop) Nisoldipine (Sular) Verapamil (Calan, Isoptin, Verelan) Alpha-Blockers Doxazosin mesylate (Cardura) Prazosin hydrochloride (Minipress) Prazosin and polythiazide (Minizide) Terazosin hydrochloride (Hytrin) Central Alpha Agonists Clonidine hydrochloride (Catapres) Clonidine hydrochloride and chlorthalidone (Clorpres, Combipres) Guanabenz Acetate (Wytensin) Guanfacine hydrochloride (Tenex) Methyldopa (Aldomet) Methyldopa and chlorothiazide (Aldoclor) Methyldopa and hydrochlorothiazide (Aldoril)

Alpha-Blockers

Alpha blockers, also called alpha-adrenergic antagonists, block the effects of adrenalinetype chemicals on alpha receptors to prevent a rise in blood pressure. They include commonly used medications such as doxazosin mesylate (Cardura) and prazosin hydrochloride (Minipress). Side effects include increased heart rate, dizziness, and orthostatic hypotension. Alpha- and beta-blockers are often combined in medications such as carvedilol (Coreg). Patients on these medications should be cautioned to change positions slowly, use fall-prevention strategies, and be aware of potential side effects.

Central Alpha Agonists

Alpha agonists, such as clonidine hydrochloride (Catapres) and methyldopa (Aldomet), lower blood pressure by stimulating alpha receptors in the brain that dilate peripheral arteries, thereby decreasing resistance and increasing blood flow. Central alpha agonists are usually prescribed when other antihypertensive medications have been ineffective. The side effects may include dry mouth and fatigue.

References

Nursing Implications

Rehabilitation nurses can prevent, diagnose and treat hypertension by recognizing risk factors and identifying those persons in need of screening. Common risk factors for hypertension include family history, African American race, male gender, increased age, sedentary lifestyle, high-sodium diet, diabetes or renal disease, high alcohol consumption, obesity, and some medications.

American Heart Association. (2005). Heart disease and stroke statistics: 2005 update [Brochure]. Dallas: Author. American Heart Association. (2006). Blood pressure lowering drugs. Retrieved April 15, 2006, from www.americanheart.org/presenter. Jones, D. (2003). New high blood pressure guidelines say start early, treat aggressively [Journal report]. Retrieved April 15, 2005, from www.americanheart.org/presenter. Kennedy-Malone, L. K., Fletcher, K. R., & Plank, L. M. (2000). Management Guidelines for Gerontological Nurse Practitioners. Philadelphia: F. A. Davis. The Washington Manual: Geriatrics Subspecialty Consult. (2005). Philadelphia: Lippincott, Williams, & Wilkins.

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