Drugs for Hypertension

1. Drugs for Hypertension Nursing Department

2. Learning Objectives At the end of the session, each student will be able to: 1. Explain how hypertension is defined and classified. 2. Explain the effects of cardiac output, peripheral resistance, and blood volume on blood pressure. 3. Discuss how the vasomotor center, baroreceptors, chemoreceptors, emotions, and hormones influence blood pressure. 4. Summarize the long-term consequences of untreated hypertension. 5. Discuss the role of therapeutic lifestyle changes in the management of hypertension.

3. Learning Objectives 6. Differentiate between drug classes used for the primary treatment of hypertension and those secondary drugs reserved for persistent hypertension. 7. Describe the nurse’s role in the pharmacologic management of patients receiving drugs for hypertension. 8. For each of the drug explain their mechanisms of drug action, primary actions, and important adverse effects. 9. Use the nursing process to care for patients receiving pharmacotherapy for hypertension.

4. Hypertension • Consistent elevation of systemic arterial blood pressure • High blood pressure • “Normal” BP varies with age • Hypertension is most common form of cardiovascular disease • Associated with more than 348,000 deaths in United States per year

5. Three Factors Responsible for Blood Pressure • Cardiac output • Peripheral resistance • Blood volume

6. Cardiac Output • Volume of blood pumped per minute • Determined by: • Stroke volume • Heart rate • Medications that affect cardiac output, stroke volume, heart rate will affect blood pressure

7. Peripheral Resistance • Friction in arteries as blood flows through vascular system • Greater resistance in arteries yields higher blood pressure • Medications that affect vascular smooth muscles may lower or raise BP • Autonomic nervous system plays role in regulating peripheral resistance

8. Blood Volume • Total amount of blood in vascular system • Increased blood volume increases blood pressure • Medications that affect blood volume may lower or raise BP • Diuretics

9. Emotions Affect Blood Pressure • Stress and anger increase • Depression and lethargy decrease

10. Hormones • Affect blood pressure • Natural hormones affect blood pressure daily • Epinephrine and norepinephrine injections raise BP • Antidiuretic hormone (ADH) raises BP by raising blood volume • Renin–angiotensin–aldosterone system is a primary homeostatic mechanism for controlling blood pressure

11. Hormonal and nervous factors influencing blood pressure

12. Types of Hypertension • Primary hypertension—no identifiable cause • Secondary hypertension—cause identified • Cushing’s syndrome • Hyperthyroidism • Chronic renal disease • Certain drugs

13. Target Organs Affected by Untreated Hypertension • Heart • Brain • Kidneys • Retina

14. Disease Progression Related to Organs • Heart failure • Cerebral vascular accident • Renal failure • Visual impairment and blindness

15. Nonpharmacologic Methods to Control Hypertension • Limit alcohol intake • Restrict sodium consumption • Reduce saturated fat and cholesterol; increase fresh fruit and vegetable intake • Increase aerobic physical activity • Discontinue tobacco use • Reduce stress • Maintain optimum weight

16. Pharmacologic Management of Hypertension • Individualized to patient's risk factors, medical conditions, degree of blood pressure elevation • Healthcare provider experience plays role in choice of therapy

17. First-Line Antihypertensive Drugs • Primary Antihypertensive Agents • Diuretics (especially thiazide and thiazide-like diuretics, potassium-sparing diuretics) • Angiotensin-converting enzyme (ACE) inhibitors • Angiotensin receptor blockers (ARBs) • Direct renin inhibitors • Calcium channel blockers (CCBs) • Prescribing two antihypertensives results in additive or synergistic blood pressure reduction

18. Second-Line Antihypertensive Drugs • Beta-adrenergic receptor blockers (in heart) • Alpha1-adrenergic receptor blockers (in arterioles) • Alpha2-adrenergic agonists • Direct-acting vasodilators • Peripherally acting adrenergic neuron blockers

19. Assessment of Patient’s Lifestyle • Dietary habits • Exercise or activity regimen • Use of medication

20. Factors That Can Help Control Blood Pressure • Losing weight • Limiting foods high in fat and sodium • Limiting use of tobacco and alcohol • Beginning an exercise program

21. Role of Nurse • Obtain complete health history • Obtain vital signs • Do physical examination • Obtain blood and urine specimens for analysis

22. Diuretics • Increase urinary excretion of water and electrolytes, thereby reducing blood volume • Used for mild to moderate hypertension • Potassium-sparing diuretics, thiazide and thiazide-like diuretics, loop/high-ceiling diuretics

23. Calcium Channel Blockers • Used to treat hypertension and other cardiovascular diseases • Block calcium ion channels; cause vasodilation, decreasing BP • Adverse effects include dizziness, headache, flushing • Some selectively target calcium channels in arterioles; others also affect cardiac muscle

24. Prototype Drug: Nifedipine (Adalat CC, Procardia XL) Therapeutic Class: Drug for hypertension and angina Pharmacologic Class: Calcium channel blocker Actions and Uses: Nifedipine is a Calcium channel blocker generally prescribed for: 1- HTN and variant or vasospastic angina. 2- It is occasionally used to treat Raynaud’s phenomenon . Nifedipine acts by selectively blocking calcium channels in myocardial and vascular smooth muscle, including those in the coronary arteries. This results in coronary artery dilation, less oxygen utilization by the heart, an increase in cardiac output, and a fall in blood pressure.

25. Prototype Drug: Nifedipine (Adalat CC, Procardia XL) Administration Alerts: • Do not administer immediate-release formulations of nifedipine if an impending MI is suspected or within 2 weeks following a confirmed MI. • Administer nifedipine capsules or tablets whole. If capsules or extended-release tablets are chewed, divided, or crushed, the entire dose will be delivered at once. • Pregnancy category C.

26. Prototype Drug: Nifedipine (Adalat CC, Procardia XL) Pharmacokinetics Adverse Effects 1- Headache, dizziness 2- Peripheral edema, and flushing 3- Reflex tachycardia 4- In rare cases, nifedipine may cause a paradoxical increase in anginal pain

27. Prototype Drug: Nifedipine (Adalat CC, Procardia XL) Contraindications: The only contraindication is prior hypersensitivity to nifedipine. Treatment of Overdose: The most likely sign of overdosage is hypotension, which is treated with vasopressors. Calcium infusions may be indicated.

28. Beta-Adrenergic Blockers • Decrease heart rate and contractility • Reduce cardiac output and lower systemic BP

29. Alpha1 Adrenergic Antagonists • Block sympathetic receptors in arterioles leading to vasodilation • Not first-line drugs for HTN • Used in combination with other drugs, usually diuretics

30. Direct Vasodilators • Cause vasodilation by direct relaxation of arterial smooth muscle • Only for severe hypertension and hypertension crisis • Serious adverse effects: reflex tachycardia, sodium and fluid retention

31. Prototype Drug: Hydralazine Therapeutic Class: Drug for hypertension and heart failure Pharmacologic Class: Direct-acting vasodilator Hydralazine was one of the first oral antihypertensive drugs marketed in the United States. It acts through a direct vasodilation of arterial smooth muscle; it has no effect on veins. Therapy is begun with low doses, which are gradually increased until the desired therapeutic response is obtained

32. Prototype Drug: Hydralazine Administration Alerts: • Abrupt withdrawal of the drug may cause rebound HTN and anxiety. • Pregnancy category C. Pharmacokinetics:

33. Prototype Drug: Hydralazine Adverse Effects: 1- Headache, reflex tachycardia, palpitations, flushing, nausea, and diarrhea 2- Rarely, the drug may produce a lupus-like syndrome that may persist for 6 months or longer. 3- Sodium and fluid retention is a potentially serious adverse effect. Contraindications: Because of its effects on the heart, hydralazine is contraindicated in: 1- Patients with angina or rheumatic mitral valve heart disease. 2- Patients with lupus should not receive hydralazine, because the drug can worsen symptoms.

34. Prototype Drug: Hydralazine Treatment of Overdose: The most likely sign of overdosage is hypotension, which may be treated with a vasopressor and/or an I V infusion of fluids.

35. Drugs for Hypertension • Assessment: • Take patient’s BP in each arm for baseline • Assess patient’s height and weight • Obtain blood and urine samples as ordered by physician • Obtain nursing history, including lifestyle, current medications, dietary habits • Assess patient’s and family’s knowledge of hypertension and medication regimen

36. Drugs for Hypertension • Planning • Goals: • Exhibit a reduction in systolic/diastolic blood pressure • Be able to explain hypertension and needed medications • Be able to verbalize ability to follow prescribed therapy

37. Drugs for Hypertension • Implementation: • Encourage compliance • Provide education regarding medication regimen • Evaluation • Ideal outcome criteria: • Lowered BP with limited side effects • Patient able to verbalize importance of taking prescribed medication

38. Nursing Practice Application Pharmacotherapy for Hypertension Assessment Baseline assessment prior to administration: • Obtain a complete health history and drug history, including allergies, current prescription and alcohol use. • Evaluate appropriate laboratory findings, electrolytes (especially potassium level), glucose, liver and kidney function studies, and lipid profiles. • Obtain baseline weight, vital signs (especially blood pressure [BP] and pulse), breath sounds.

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44. Review Questions 1- The client has been given a prescription of furosemide (Lasix) as an adjunct to treatment of hypertension and returns for a follow-up check. Which of the following is the most objective data for determining the therapeutic effectiveness of the furosemide? 1. Absence of edema in lower extremities 2. Weight loss of 6 lb 3. Blood pressure log notes blood pressure 120/70 mmHg to 134/88 mmHg since discharge 4. Frequency of voiding of at least six times per day

45. Review Questions 2- Nifedipine (Procardia) has been ordered for a client with hypertension. In the care plan, the nurse includes the need to monitor for which adverse effect? 1. Rash and chills 2. Reflex tachycardia 3. Increased urinary output 4. Weight loss

46. Review Questions 3- What health teaching should the nurse provide for the client receiving nadolol (Corgard)? 1. Increase fluids and fiber to prevent constipation. 2. Report a weight gain of 1 kg per month or more. 3. Immediately stop taking the medication if sexual dysfunction occurs. 4. Rise slowly after prolonged periods of sitting or lying down.

47. Review Questions 4- A client with significant hypertension unresponsive to other medications is given a prescription for hydralazine (Apresoline). An additional prescription of propranolol (Inderal) is also given to the client. The client inquires why two drugs are needed. What is the nurse’s best response? 1. Giving the two drugs together will lower the blood pressure even more than just one alone. 2. The hydralazine may cause tachycardia and the propranolol will help keep the heart rate within normal limits. 3. The propranolol is to prevent lupus erythematosus from developing. 4. Direct-acting vasodilators such as hydralazine cause fluid retention and the propranolol will prevent excessive fluid buildup.