McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 4 3 Drugs affecting blood pressure

of the drug : any known allergies to these drugs; impaired kidney or liver function; pregnancy or breastfeeding because of the potential adverse effects on the fetus or neonate ; and cardiovascular dysfunction, which could be exacerbated by a fall in blood pressure. ■ ■ Assess baseline status before beginning therapy to determine any potential adverse effects ; this includes body temperature and weight; skin colour, lesions and temperature; pulse, blood pressure, baseline ECG and perfusion; respirations and adventitious breath sounds; bowel sounds and abdominal examination; renal and liver function tests; and blood glucose. Implementation with rationale ■ ■ Encourage the person to implement lifestyle changes, including weight loss, smoking cessation, decreased alcohol and salt in the diet and increased exercise, to increase the effectiveness of antihypertensive therapy. administration to evaluate for effectiveness and to ensure quick response if blood pressure falls rapidly or too much. ■ ■ Monitor blood glucose and serum electrolytes to avoid potentially serious adverse effects. ■ ■ Monitor the person carefully in any situation that might lead to a drop in fluid volume (e.g. excessive sweating, vomiting, diarrhoea, dehydration) to detect and treat excessive hypotension that may occur. ■ ■ Provide comfort measures to help the person tolerate drug effects , including small, frequent meals; access to bathroom facilities; safety precautions if CNS effects occur; environmental controls; appropriate skin care as needed; and analgesics as needed. ■ ■ Provide thorough teaching, including the name of the drug, dosage prescribed, measures to avoid adverse effects, warning signs of problems and the need for periodic monitoring and evaluation, to enhance knowledge about drug therapy and to promote compliance. ■ ■ Offer support and encouragement to help the person deal with the diagnosis and the drug regimen. Evaluation ■ ■ Monitor response to the drug (maintenance of blood pressure within normal limits). ■ ■ Monitor for adverse effects (hypotension, GI distress, skin reactions, tachycardia, headache, dizziness). ■ ■ Monitor blood pressure closely during

■ ■ Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for, specific measures to avoid them and the importance of continued follow-up). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen.

O ther antihypertensive agents Diuretic agents

Diuretics are drugs that increase the excretion of sodium and water from the kidney (Figure 43.3). See Chapter 51 for a detailed discussion of these agents. Diuretics are very important for the treatment of hypertension. These drugs are often the first agents tried in mild hypertension; they affect blood sodium levels and blood volume. A somewhat controversial study, the Anti­ hypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), reported in 2002 that people taking the less expensive, less toxic diuretics did better and had better blood pressure control than people using other antihypertensive agents. Replica- tions of this study have supported its findings and the use of a thiazide diuretic as the first drug used in the management of hypertension. Although these drugs increase urination and can disturb electrolyte and acid–base balances, they are usually tolerated well by most people. Diuretic agents used to treat hypertension include the following: • Thiazide and thiazide-like diuretics : hydrochlorothiazide ( Dithiazide ), chlorthalidone ( Hygroton ) and indapamide ( Dapa-Tabs ). • Potassium-sparing diuretics : amiloride ( Amizide, Kaluril ), spironolactone ( Aldactone, Spiractin ) and triamterene ( Hydrene ). Sympathetic nervous system blockers Drugs that block the effects of the sympathetic nervous system are useful in blocking many of the compen- satory effects of the sympathetic nervous system (see Figure 43.3). See Chapters 30 and 31 for a detailed dis- cussion of these drugs. • Beta-blockers block vasoconstriction, decrease heart rate, decrease cardiac muscle contraction and tend to increase blood flow to the kidneys, leading to a decrease in the release of renin. These drugs have many adverse effects and are not recommended for all people. They are often used as monotherapy, and in some people they control blood pressure adequately. Beta-blockers used to treat hypertension include the following agents: atenolol ( Tenormin ), betaxolol ( Betoquin ), metoprolol ( Betaloc ,