Antihypertensive Drugs
TERMS
□ captopril (Capoten)
□ clonidine (Catapres)
□ losartan (Cozaar)
□ prazosin (Minipress)
□ sodium nitroprusside (Nipride)
QUICK LOOK AT THE CHAPTER AHEAD
Hypertension is often known as the silent killer, as clients may be asymptomatic. There is an abnormal increase in blood pressure (BP) and without treatment, hypertension can lead to progressive deterioration of cardiac, renal, and ocular function, and cerebral vascular accident (CVA).
In clients diagnosed with hypertension, 90% of hypertensive cases are known as essential, idiopathic, or primary hypertension and the cause is not known. In 10% of the cases, the cause is known and is called secondary hypertension. It can be caused by pheochromocytoma, renal disease, eclampsia, or by other medications.1 If the cause of secondary hypertension is cured, then the blood pressure generally returns to normal.
In 2003, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, from the National Institutes of Health released its seventh report that provides a new guidelines for hypertension prevention and management.
The guideline states: “in individuals over age 50, systolic BP over 140 mmHg is a more important cardiovascular disease (CVD) risk factor than diastolic BP; the risks of CVD beginning at 115/75 mmHg, doubles with each increment of 20/10 mmHg; individuals who are normotensive at age 55 have a 90% lifetime risk for developing hypertension; a systolic BP of 120 to 139 mmHg or a diastolic BP of 80 to 89 mmHg should be considered as prehypertensive and requires lifestyle modifications; Thiazides should be used in treatment for most clients with uncomplicated hypertension, alone or in combination with other drugs from
other classes; most clients will require two or more antihypertensives for BP to be <140/90 mmHg or <130/90 for patients with kidney disease; if BP is more than 20/10 mmHg above goal BP, consider initiating two agents (one a thiazide diuretic); Motivation by the client makes antihypertensive therapy more successful.”2
other classes; most clients will require two or more antihypertensives for BP to be <140/90 mmHg or <130/90 for patients with kidney disease; if BP is more than 20/10 mmHg above goal BP, consider initiating two agents (one a thiazide diuretic); Motivation by the client makes antihypertensive therapy more successful.”2
There are six classes of antihypertensives:
Adrenergic agents (including: alpha-adrenergic blockers, beta-blockers, centrally-acting adrenergic agents, peripherally acting adrenergic agents, and combined alpha-beta-blockers)
Calcium channel blockers (CCBs)
Diuretics
Angiotensin-converting enzyme (ACE) inhibitors
Angiotensin II receptor blockers
Vasodilators
Beta-blockers, CCBs, and diuretics will not be discussed in this chapter as they are covered in Chapters 40, 41, and 43.
It is imperative that the client also make lifestyle modifications to reduce coronary and stroke risk factors, which include proper diet, exercise, weight management, stress management, and smoking cessation.
Table 42-1 Antihypertensive Drugs | ||||||||||||||||||||||||||||||
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ANTIHYPERTENSIVES CLIENT TEACHING
Instruct clients on proper nutrition (decrease sodium intake, follow DASH diet), exercise, and managing stress.
Do not abruptly stop taking medication as this can lead to rebound hypertension.
Do not take OTC medications or herbal remedies without first consulting your health care provider.
If a dose is missed, contact health care provider on what action to take.
Do not strain when having a bowel movement since this can stimulate the Valsalva maneuver.
Avoid alcohol due to its additive hypotension effect.
Saunas, hot weather, hot showers, or baths and hot tubs may cause an additive hypotensive effect, causing dizziness. Sit or lie down until dizziness subsides.
Monitor blood pressure.
Contact health care provider if experiencing adverse effects, and do not stop taking medication without consulting health care provider.
Instruct clients taking prazosin (Minipress) that the first dose will cause a drop in blood pressure. Clients should take the first dose at bedtime and lying down. Instruct clients that this disappears with time or after a reduction in dosage.
Clients taking alpha-blockers and ACE inhibitors should monitor their weight and report changes to their health care provider.
Clients taking rauwolfia alkaloids should report symptoms of mental depression to their health care provider.
Drowsiness or dizziness is an adverse effect with many antihypertensives, and as a result clients should not take CNS depressants, and should use extra caution when operating heavy machinery until the personal effects of drug are known.
Clients taking ACE inhibitors should report bruising, bleeding, infection, or weight gain or loss to health care provider.
Clients taking ACE inhibitors should avoid using salt substitutes that contain potassium, as an adverse effect of these agents is hyperkalemia.
Instruct clients on proper nutrition (decrease sodium intake, follow DASH diet), exercise, and managing stress.
Do not abruptly stop taking medication as this can lead to rebound hypertension.
Monitor blood pressure.
Contact health care provider if experiencing adverse effects, and do not stop taking medication without consulting health care provider.
ACTIONAlpha1– and Beta-Receptor Blockers
Block alpha1 receptors causing vasodilation and blocks beta receptors causing a decreased heart rate, cardiac output, and renin release from kidneys
Alpha-Adrenergic Blockers (Alpha1-Blockers)
Block stimulation of the sympathetic nervous system at the alpha1-adrenergic receptor, which causes vasodilatation and reduces blood pressure
Centrally-Acting Adrenergic Agents (Alpha2-Agonists)
Work within the brainstem to suppress sympathetic outflow, by stimulating central alpha2 receptors, to the heart and blood vessels, which results in vasodilatation and decreased cardiac output and reduces BP
Peripherally-Acting Adrenergic Neuronal Blockers and Rauwolfia Alkaloids
These drugs work peripherally to inhibit the release of norepinephrine (guanadrel [Hylorel] and guanethidine [Ismelin]).
Reserpine (Novoreserpine) causes norepinephrine depletion.
All of these drugs decrease sympathetic stimulation of the heart and blood vessels which decreases BP. Reserpine is derived from the Rauwolfia serpentina plant.
Angiotensin-Converting Enzyme (ACE) Inhibitors
Inhibit the angiotensin-converting enzyme, responsible for converting angiotensin I to angiotensin II, and inactivate bradykinin and other prostaglandins
Reduce aldosterone levels causing vasodilatation and lower BP
Angiotensin II Receptor Blockers
Block the vasoconstrictive and aldosterone-producing effects of Angiostensin II at the receptor sites, which causes vasodilatation and lowered BP
Vasodilators
Directly act on arterial smooth muscle to cause vasodilatation and lower BP
USEAlpha1– and Beta-Adrenergic Blockers
Treatment of hypertension may be used alone or with a diuretic or other antihypertensives.
Carvedilol (Coreg) also used to treat CHF.
Alpha-Adrenergic Blockers (Alpha1-Blockers)
Treatment of hypertension may be used alone or with other antihypertensives.
Centrally-Acting Adrenergic Agents (Alpha2-Agonists)
Generally used as adjunct agents to treat hypertension or may be used with a diuretic or other antihypertensives
Due to their side effects (drowsiness, orthostatic hypertension, dizziness), they are not usually prescribed as first-line antihypertensive agents.3
Clonidine (Catapres)
Also has an unlabeled use to treat opioid and nicotine withdrawal3
Epidural clonidine (Catapres) is indicated for treatment of cancer pain unresponsive to opioids.
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