chapter 22 antihypertensive drugs copyright © 2014 by mosby, an imprint of elsevier inc

Chapter 22

Antihypertensive Drugs

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Blood Pressure

Blood pressure = CO × SVR CO = cardiac output SVR = systemic vascular resistance

Hypertension = high blood pressure

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2

Four stages, based on BP measurements

1. Normal

2. Prehypertension

3. Stage 1 hypertension

4. Stage 2 hypertension

*New guidelines pending

Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and

Treatment of High Blood Pressure (JNC-7)*


Hypertension can also be defined by its cause Unknown cause

Essential, idiopathic, or primary hypertension 90% of cases

Known cause Secondary hypertension 10% of cases

Classification of BP


Classroom Response Question

The number of people with hypertension in the United States is estimated to be:

A.10 million.

B.50 million.

C.75 million.

D.100 million.


Parasympathetic nervous system Stimulates smooth muscle, cardiac muscle, glands

Sympathetic nervous system Stimulates the heart, blood vessels, skeletal muscle

Autonomic Nervous System


Location of the Nicotinic Receptors in the PNS and SNS


Medications used to treat hypertension Categories

Adrenergic drugs Angiotensin-converting enzyme (ACE) inhibitors Angiotensin II receptor blockers (ARBs) Calcium channel blockers (CCBs) Diuretics Vasodilators Direct renin inhibitors

Antihypertensive Drugs


Centrally and peripherally acting adrenergic neuron blockers

Centrally acting alpha2 receptor agonists

Peripherally acting alpha1 receptor blockers

Adrenergic Drugs: Five Subcategories


Peripherally acting beta receptor blockers (beta blockers) Cardioselective (beta1 receptors)

Nonselective (both beta1 and beta2 receptors)

Peripherally acting dual alpha1 and beta receptor blockers

Adrenergic Drugs: Five Subcategories (cont’d)


Centrally acting alpha2 receptor agonists Stimulate alpha2-adrenergic receptors in the brain

Decrease sympathetic outflow from the CNS Decrease norepinephrine production Stimulate alpha2-adrenergic receptors, thus reducing

renin activity in the kidneys Result in decreased blood pressure

Adrenergic Drugs


Centrally acting alpha2 receptor agonists (cont’d) clonidine (Catapres) methyldopa (Aldomet)

• Can be used for hypertension in pregnancy

Adrenergic Drugs (cont’d)


Peripheral alpha1 blockers/antagonists Block alpha1-adrenergic receptors

doxazosin (Cardura) terazosin (Hytrin) prazosin (Minipress)



Beta blockers Reduce BP by reducing heart rate through beta1

blockade Cause reduced secretion of renin Long-term use causes reduced peripheral vascular

resistance Examples: nebivolol (Bystolic), propranolol (Inderal),

atenolol (Tenormin), others



Dual-action alpha1 and beta receptor blockers Reduce heart rate (beta1 receptor blockade)

Cause vasodilation (alpha1 receptor blockade)

carvedilol (Coreg) and labetalol Result in decreased blood pressure



All used to treat hypertension Centrally acting alpha2 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

Adrenergic Drugs: Indications


Peripherally acting alpha1 receptor agonists Treatment of hypertension Some used to relieve symptoms of BPH

• tamsulosin (Flomax)

Management of severe heart failure (HF) when used with cardiac glycosides and diuretics

Adrenergic Drugs: Indications (cont’d)


High incidence of orthostatic hypotension Most common

Bradycardia with reflex tachycardia Dry mouth Drowsiness, sedation Constipation Depression Edema Sexual dysfunction

Adrenergic Drugs: Adverse Effects


Adrenergic Drugs: Adverse Effects (cont’d)

Other Headaches Sleep disturbances Nausea Rash Cardiac disturbances (palpitations), others



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.


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


captopril (Capoten) benazepril (Lotensin) enalapril (Vasotec) fosinopril (Monopril) lisinopril (Prinivil) moexipril (Univasc) quinapril (Accupril) Others

ACE Inhibitors (cont’d)


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


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 (cont’d)


Hypertension HF (either alone or in combination with diuretics

or other drugs) Slow progression of left ventricular hypertrophy

after MI (cardioprotective) Renal protective effects in patients with diabetes

ACE Inhibitors:Indications



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 cardioprotective properties.

D. This medication has a protective effect on the kidneys for patients with type II diabetes.


Drugs of choice in hypertensive patients with HF Drugs of choice for diabetic patients

ACE Inhibitors: Indications (cont’d)



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


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 (cont’d)


Fatigue Dizziness Headache Mood changes Impaired taste Possible hyperkalemia Dry, nonproductive cough, which reverses when

therapy is stopped Angioedema: rare but potentially fatalNote: First-dose hypotensive effect may occur

ACE Inhibitors: Adverse Effects


Also referred to as angiotensin II blockers or ARBs

Well tolerated Do not cause a dry cough

Angiotensin II Receptor Blockers


losartan (Cozaar) eprosartan (Teveten) valsartan (Diovan) irbesartan (Avapro) candesartan (Atacand) olmesartan (Benicar) telmisartan (Micardis) azilsartan (Edarbi)

Angiotensin II Receptor Blockers


Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II

Block vasoconstriction and release of aldosterone

Angiotensin II Receptor Blockers: Mechanism of Action


Hypertension Adjunctive drugs for the treatment of HF May be used alone or with other drugs such as

diuretics

Angiotensin II Receptor Blockers: Indications


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



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.


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


Angina Hypertension Dysrhythmias Migraine headaches Raynaud’s disease

Calcium Channel Blockers: Indications


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

Diuretics


Thiazide diuretics are the most commonly used diuretics for hypertension

Listed as first-line antihypertensives in the JNC-7 guidelines

Diuretics (cont’d)


diazoxide (Hyperstat) hydralazine HCl (Apresoline) minoxidil (Loniten) sodium nitroprusside (Nipride, Nitropress)

Vasodilators


Directly relax arteriolar and/or venous smooth muscle

Results in: Decreased systemic vascular response Decreased afterload Peripheral vasodilation

Vasodilators:Mechanism of Action


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


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


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 regular BP checks

Nursing Implications (cont’d)


Instruct patients that these drugs should not be stopped abruptly because this may cause a rebound hypertensive crisis, and perhaps lead to stroke

Oral forms should be given with meals so that absorption is more gradual and effective

Administer IV forms with extreme caution, and use an IV pump



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



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; weight gain or loss; chest pain; palpitations; or excessive fatigue



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



Hot tubs, 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 any other medications, including over-the-counter drugs, without first getting the approval of their physician



Educate patients about lifestyle changes that may be needed Weight loss Stress management Supervised exercise Dietary measures



Monitor for adverse effects (dizziness, orthostatic hypotension, fatigue) and for toxic effects

Monitor for therapeutic effects



chapter 22 antihypertensive drugs copyright © 2014 by mosby, an imprint of elsevier inc

Documents

imprint of elsevier

acting alpha

subcategories copyright

sns copyright

high blood pressure

adrenergic neuron blockers

subcategories contd

blood pressure blood