Lilley Pharmacology Antihypertensive Drugs

Blood Pressure Review Blood pressure = CO × SVR CO = cardiac output SVR = systemic vascular resistance Hypertension = high blood pressure 2

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Stages of Blood Pressure 1. Normal <120 over </ Prehypertension 120 or >/ 80 or > 3. Hypertension 140/90 4

Hypertension can also be defined by its cause Unknown Cause  Essential, or Primary Hypertension  90-95% of cases Known cause  Secondary hypertension  Approximately 10% of cases Classification of BP 5

Medications used to treat hypertension Categories  Adrenergic drugs  Angiotensin-converting enzyme (ACE) inhibitors  Angiotensin II receptor blockers (ARBs)  Calcium channel blockers (CCBs)  Beta blockers  Diuretics  Vasodilators  Direct renin inhibitors Antihypertensive Drugs 6

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Centrally acting alpha 2 receptor agonists  Stimulate alpha 2 -adrenergic receptors in the brain  Decrease sympathetic outflow from the CNS  Stimulate alpha 2 -adrenergic receptors, thus reducing renin activity in the kidneys  Alpha blockers relax certain muscles and help small blood vessels remain open  They work by keeping the hormone norepinephrine from tightening the muscles in the walls of smaller arteries and veins  Blocking that effect causes the vessels to remain open and relaxed. This improves blood flow and lowers blood pressure  Results in decreased blood pressure  Example: doxazosin (Cardura) Adrenergic Drugs Actions 8

Peripheral alpha 1 blockers/antagonists  Block alpha 1 -adrenergic receptors  doxazosin (Cardura)  terazosin (Hytrin)  prazosin (Minipress)  First dose phenomena, tachycardia, dyspnea, feeling faint Adrenergic Drugs 9

Beta blockers  Reduce BP by reducing heart rate through beta 1 blockade  Cause reduced secretion of renin  Long-term use causes reduced peripheral vascular resistance  Examples: nebivolol (Bystolic), propranolol (Inderal), atenolol (Tenormin), metoprolol (Lopressor) Adrenergic Drugs 10

Dual-action alpha 1 and beta receptor blockers  Reduce BP & heart rate (beta 1 receptor blockade)  Cause vasodilation (alpha 1 receptor blockade)  Examples: carvedilol (Coreg) and labetalol (Normadyne, Trandate)  Result in decreased blood pressure & HR Adrenergic Drugs 11

All used to treat hypertension Centrally acting alpha 2 receptor agonists  Treatment of hypertension, either alone or with other drugs  Usually used after other drugs have failed because of adverse effects  Clonidine is useful in the management of withdrawal symptoms in opioid-dependent persons (reduces anxiety and restlessness) Adrenergic Drugs: Indications 12

Peripherally acting alpha 1 receptor agonists  Treatment of hypertension  Some used to relieve symptoms of benign prostatic hyperplasia (BPH)- vasodilating effect  Management of severe heart failure (HF) when used with cardiac glycosides and diuretics Adrenergic Drugs: Indications (cont’d) 13

High incidence of orthostatic hypotension Most common  Bradycardia with reflex tachycardia  Dry mouth  Drowsiness, sedation  Constipation  Depression  Edema  Sexual dysfunction Adrenergic Drugs: Adverse Effects 14

Adrenergic Drugs: Adverse Effects Other  Headaches  Sleep disturbances  Nausea  Rash  Cardiac disturbances (palpitations) 15

Classroom Response Question When administering an alpha-adrenergic drug for hypertension, it is most important for the nurse to assess the patient for the development of: A.hypotension. B.hyperkalemia. C.oliguria. D.respiratory distress. 16

Large group of safe and effective drugs Often used as first-line drugs for HF and hypertension May be combined with a thiazide diuretic or calcium channel blocker Angiotensin-Converting Enzyme (ACE) Inhibitors 17

captopril (Capoten) benazepril (Lotensin) enalapril (Vasotec) fosinopril (Monopril) lisinopril (Prinivil) moexipril (Univasc) quinapril (Accupril) ACE Inhibitors Examples 18

Inhibit angiotensin-converting enzyme, which is responsible for converting angiotensin I (through the action of renin) to angiotensin II Angiotensin II is a potent vasoconstrictor and causes aldosterone secretion from the adrenal glands ACE Inhibitors: Mechanism of Action 19

Block angiotensin-converting enzyme, thus preventing the formation of angiotensin II Prevent the breakdown of the vasodilating substance bradykinin Result in decreased systemic vascular resistance (afterload), vasodilation, and therefore decreased blood pressure ACE Inhibitors: Mechanism of Action 20

Hypertension HF (either alone or in combination with diuretics or other drugs) Slow progression of left ventricular hypertrophy after MI (cardio protective) Renal protective effects in patients with diabetes ACE Inhibitors: Indications 21

Classroom Response Question A patient with type II diabetes has a new prescription for the angiotensin- converting enzyme (ACE) inhibitor lisinopril. She questions this order because her physician has never told her that she has hypertension. What is the best explanation for this order? A.The doctor knows best. B.The patient is confused. C.This medication has cardio-protective properties. D.This medication has a protective effect on the kidneys for patients with type II diabetes. 22

Drugs of choice in hypertensive patients with HF Drugs of choice for diabetic patients ACE Inhibitors: Indications (cont’d) 23

Captopril and lisinopril are NOT prodrugs Prodrugs are inactive in their administered form and must be metabolized in the liver to an active form so as to be effective Captopril and lisinopril can be used if a patient has liver dysfunction, unlike other ACE inhibitors that are prodrugs ACE Inhibitors 24

Classroom Response Question A patient with a history of pancreatitis and cirrhosis is also being treated for hypertension. Which drug will most likely be ordered for this patient? A.clonidine B.prazosin C.diltiazem D.captopril 25

Fatigue Dizziness Headache Mood changes Impaired taste Dry, nonproductive cough, which reverses when therapy is stopped Angioedema: rare but potentially fatal Potential hyperkalemia First dose hypotension may occur ACE Inhibitors: Adverse Effects 26

Also referred to as angiotensin II blockers or ARBs Well tolerated Rarely cause a dry cough Angiotensin II Receptor Blockers 27

losartan (Cozaar) valsartan (Diovan) irbesartan (Avapro) candesartan (Atacand) olmesartan (Benicar) telmisartan (Micardis) Angiotensin II Receptor Blockers 28

Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II Block vasoconstriction and release of aldosterone – results in vasodilation Angiotensin II Receptor Blockers: Mechanism of Action 29

Hypertension Adjunctive drugs for the treatment of HF May be used alone or with other drugs such as diuretics Angiotensin II Receptor Blockers: Indications 30

Upper respiratory infections Headache May cause occasional dizziness, inability to sleep, diarrhea, dyspnea, heartburn, nasal congestion, back pain, fatigue Hyperkalemia much less likely to occur Angiotensin II Receptor Blockers: Adverse Effects 31

Classroom Response Question Which statement about angiotensin II receptor blockers does the nurse identify as being true? A.Hyperkalemia is more likely to occur than when using ACE inhibitors. B.Cough is more likely to occur than when using ACE inhibitors. C.Upper respiratory infection is a common adverse effect. D.Overdose is usually manifested by hypertension and bradycardia. 32

Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing muscle contraction Results in:  Decreased peripheral smooth muscle tone  Decreased systemic vascular resistance  Decreased blood pressure Calcium Channel Blockers: Mechanism of Action 33

Angina Hypertension Dysrhythmias Migraine headaches Raynaud’s disease Calcium Channel Blockers: Indications 34

Beta Blockers Beta-blockers are used for their antagonistic effect on cardiac beta-1 adrenoceptors Two types of beta-blockers are available: beta-1 selective adrenoceptor antagonists (metoprolol, atenolol) And nonselective beta-1/ beta-2 adrenoceptor antagonists cardiac & pulmonary effect (carvedilol, propranolol, sotalol, timolol). Beta-2 receptor antagonism is associated with bronchoconstriction. Many commercially available beta-1 selective blockers have high affinity for beta-2 receptors So, both selective and nonselective beta-blockers may cause bronchoconstriction, which can lead some patients to experience a cough reflex. 35

Decrease plasma and extracellular fluid volumes Results  Decreased preload  Decreased cardiac output  Decreased total peripheral resistance Overall effect  Decreased workload of the heart and decreased blood pressure (from decreased volume) Diuretics 36

Thiazide diuretics are the most commonly used diuretics for hypertension Listed as first-line antihypertensives guidelines Diuretics 37

diazoxide (Hyperstat) hydralazine HCl (Apresoline) sodium nitroprusside used in ICU (Nipride, Nitropress) Vasodilators 38

Directly relax arteriolar and/or venous smooth muscle Results in:  Decreased systemic vascular response  Decreased afterload  Peripheral vasodilation Vasodilators: Mechanism of Action 39

Treatment of hypertension May be used in combination with other drugs Sodium nitroprusside and intravenous diazoxide are reserved for the management of hypertensive emergencies Vasodilators: Indications 40

Before beginning therapy, obtain a thorough health history and head-to-toe physical examination Assess for contraindications to specific antihypertensive drugs Assess for conditions that require cautious use of these drugs Nursing Implications 41

Educate patients about the importance of not missing a dose and taking the medications exactly as prescribed Instruct patients to check with their physician for instructions on what to do if a dose is missed; patients should never double up on doses if a dose is missed Monitor BP during therapy; instruct patients to keep a journal of BP checks Nursing Implications 42

Instruct patients that these drugs should not be stopped abruptly because this may cause a rebound hypertensive crisis, and perhaps lead to stroke Administer IV forms with extreme caution, and use an IV pump Oral forms should be given with meals or per label, so that absorption is more gradual Nursing Implications 43

Remind patients that medication is only part of therapy Encourage patients to watch their diet, stress level, weight, and alcohol intake Instruct patients to avoid smoking and eating foods high in sodium Encourage supervised exercise Nursing Implications 44

Teach patients to change positions slowly to avoid syncope from postural hypotension Instruct patients to report unusual shortness of breath, difficulty breathing, swelling of the feet, ankles, face, or around the eyes Report weight gain or loss, chest pain, palpitations, or excessive fatigue (HF symptoms) Nursing Implications 45

Male patients who take these drugs may not be aware that impotence is an expected effect, and this may influence compliance with drug therapy If patients are experiencing serious adverse effects, or if they believe the dose or medication needs to be changed, they should contact their physician immediately Nursing Implications 46

Hot showers, or baths; hot weather; prolonged sitting or standing; physical exercise; and alcohol ingestion may aggravate low blood pressure, leading to fainting and injury; patients should sit or lie down until symptoms subside Patients should not take over-the-counter drugs, without first getting the approval of their physician, and discuss all other medications they are taking Nursing Implications 47

Educate patients about lifestyle changes that may be needed  Weight loss  Stress management  Supervised exercise  Dietary measures Nurses: Monitor for adverse effects including dizziness, orthostatic hypotension Monitor for therapeutic effects- which would be? Nursing Implications 48