Antihypertensive drugs affect different areas of blood pressure control so in most cases, these agents are combined for synergistic effect.

Ninety percent of cases of hypertension have no known cause. Therefore, the main action of antihypertensive agents is to alter the body’s regulating mechanisms (e.g. baroreceptors, renin-angiotensin-aldosterone system, etc.) responsible for maintaining normal blood pressure.

Different people have different responses towards hypertensive agents because hypertension is multifactorial. For an instance, the presence of comorbidities (e.g. diabetes, myocardial infarction, etc.) may make some antihypertensives not suitable for treatment. 

Contents

Table of Common Drugs and Generic Names


Here is a table of commonly encountered antihypertensive drugs, their generic names, and brand names:

Classification Generic Name Brand Name
Angiotensin-Converting Enzyme (ACE) Inhibitors benazepril Lotensin
captopril Capoten
enalapril Vasotec IV
quinapril Accupril
Angiotensin II-Receptor Blockers (ARBs) irbesartan Avapro
losartan Cozaar
telmisartan Micardis
valsartan Diovan
Calcium-channel blockers amlodipine Norvasc
diltiazem Diltiazem
nicardipine Cardene
nifedipine Adalat, Procardia
verapamil Calan, Isoptin
Vasodilators hydralazine Apresoline
minoxidil Loniten
nitropruisside Nitropress
Others: 
Renin inhibitor aliskiren Tekturna

Disease Spotlight: Hypertension


Hypertension affects 20% of the population of the United States alone.

Types

Ninety percent of these cases have no known cause and is termed as essential hypertension. Of this type, there is elevated total peripheral resistance. Also, the organs are perfused effectively and people with essential hypertension usually exhibit no symptoms. It is also the reason why hypertension is tagged as the “silent killer.”

Another type of hypertension called secondary hypertension is characterized by elevated blood pressure due to a known cause. For example, a tumor in the adrenal medulla called phaeochromocytoma can cause the organ to release a high amount of catecholamines, which greatly increase blood pressure.

Categories

A category rating the severity of hypertension has been devised and the classifications of blood pressure are as follows:

  • Normal – systolic: <120 mmHg; diastolic: <80
  • Prehypertension – systolic: 120-139; diastolic: 80-89
  • Class I Hypertension – systolic: 140-159; diastolic: 90-99
  • Class II Hypertension – systolic: less than or equal to 160; diastolic: less than or equal to 100

ACE Inhibitors


Description

  • Angiotensin-converting enzymes inhibitors (ACE Inhibitors) are antihypertensive agents that act in the lungs to prevent the conversion of angiotensin I into angiotensin II, which is a potent vasoconstrictor.

Therapeutic Action

  • By preventing the production of angiotensin II which is a potent vasoconstrictor and a stimulator of aldosterone release, blood pressure is decreased with resultant loss of serum sodium and fluid but with a slight increase in serum potassium.

Indications

  • Primarily indicated for hypertension and can be used alone or in combination with other drugs.
  • Aside from its indication in treating hypertension, it is also combined with diuretics and digoxin in the treatment of heart failure and left ventricular dysfunction. The resultant effect is decreased in peripheral resistance and blood volume leading to decreased cardiac workload.
  • It is also approved for treatment of diabetic nephropathy, in which the renal artery is being damaged by diabetes. It is thought that decreased in stimulation of angiotensin receptors in the kidney will slow down the damage in the renal artery.
  • Children: safety and efficacy of ACE inhibitors has not been established in this age group.
  • Adults: ACE inhibitors are not allowed during pregnancy.
  • Older adults: are more susceptible to drug toxicity because of underlying conditions that would interfere with metabolism and excretion of drug. Renal and hepatic function should always be monitored.

Pharmacokinetics

Route Onset Peak
Oral 15 min 30-90 min
T1/2: 2 h
Metabolism: liver
Excretion: urine

Contraindications and Cautions

  • Allergy to ACE inhibitors. Prevent severe hypersensitivity reactions.
  • Renal impairment. Decreased renal blood flow effect of these drugs can exacerbate renal impairment.
  • Heart failure. Changes in hemodynamics caused by these drugs can exacerbate heart failure.
  • Hyponatremia and hypovolemia. Can be exacerbated by the therapeutic effects of the drug.
  • Pregnancy and lactation. Can cause potential adverse effects to the fetus and can decrease milk production. Pregnant women are advised to use barrier type of contraceptives while taking this drug.

Adverse Effects

  • GI: irritations, ulcer, constipation, liver injury
  • GU: renal insufficiency, renal failure, proteinuria
  • CV: reflex tachycardia, chest pain, heart failure, cardiac arrhythmias
  • EENT: rash, alopecia, dermatitis, photosensitivity
  • Captopril is associated with sometimes-fatal pancytopenia, cough, and GI distress.

Interactions

  • Allopurinol: increased risk for hypersensitivity
  • NSAIDs: increased risk for decreased antihypertensive effects

Nursing Considerations

Here are important nursing considerations when administering this drug:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned contraindications to this drug (e.g. renal impairment, hyponatremia, hypovolemia, etc.) to prevent potential adverse effects.
  • Obtain baseline status for weight, vital signs, overall skin condition, and laboratory tests like renal and hepatic function tests, serum electrolyte, and complete blood count (CBC) with differential to assess patient’s response to therapy.

Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of this drug for therapy:

Implementation with Rationale

These are vital nursing interventions done in patients who are taking ACE inhibitors:

  • Educate patient on importance of healthy lifestyle choices which include regular exercise, weight loss, smoking cessation, and low-sodium diet to maximize the effect of antihypertensive therapy.
  • Administer drug on empty stomach one hour before or two hours after meal to ensure optimum drug absorption.
  • Monitor renal and hepatic function tests to alert doctor for possible development of renal and/or hepatic failure as well as to signal need for reduced drug dose.
  • Monitor for presence of manifestations that signal decreased in fluid volume (e.g. diarrhea, vomiting, dehydration) to prevent exacerbation of hypotensive effect of drug.
  • Educate patient and family members about drug’s effect to the body and manifestations that would need reporting to enhance patient knowledge on drug therapy and promote adherence.

Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug therapy:

  • Monitor patient response to therapy through blood pressure monitoring.
  • Monitor for adverse effects (e.g. hypotension, arrhythmias, renal failure, cough, and pancytopenia).
  • Evaluate patient understanding on drug therapy by asking patient to name the drug, its indication, and adverse effects to watch for.
  • Monitor patient compliance to drug therapy.

Angiotensin II-Receptor Blockers


Description

  • ARBs are antihypertensive agents that exert their action by blocking vasoconstriction and release of aldosterone through selective blocking of angiotensin II receptors in vascular smooth muscles and adrenal cortex.

Therapeutic Action

  • The main action is to block the blood pressure raising effect of the renin-angiotensin-aldosterone system (RAAS).

Indications

  • Like ACE inhibitors, they can also be used alone for treatment of hypertension or in combination with other antihypertensive agents.
  • Utilized in treatment of heart failure for patients who do not respond to ACE inhibitors.
  • By blocking the effects of angiotensin receptors in vascular endothelium, these drugs are able to slow down the progress of renal disease in patients with type 2 diabetes and hypertension.
  • Children: safety and efficacy of ARBs has not been established in this age group.
  • Adults: ARBs are not allowed during pregnancy.
  • Older adults: are more susceptible to drug toxicity because of underlying conditions that would interfere with metabolism and excretion of drug. Renal and hepatic function should always be monitored.

Pharmacokinetics

Route Onset Peak Duration
Oral Varies 1-3 h 24 h
T1/2: 2 h
Metabolism: liver
Excretion: urine and feces

Contraindications and Cautions

  • Allergy to ARBs. Prevent severe hypersensitivity reactions.
  • Renal and hepatic impairment. Can alter metabolism and excretion of drugs which can increase the risk for toxicity.
  • Hypovolemia. Can be exacerbated by the drug’s action on blocking important life-saving compensatory mechanisms.
  • Pregnancy and lactation. Can cause potential adverse effects to the fetus and potential termination of pregnancy between second and third trimester. It is still not known whether ARBs can enter breast milk but it is generally not allowed in lactating women because of potential adverse effects to the neonate.

Adverse Effects

  • CNS: headache, dizziness, syncope, weakness
  • Respiratory: symptoms of upper respiratory tract infections (URTI), cough
  • GI: diarrhea, abdominal pain, nausea, dry mouth, tooth pain
  • EENT: rash, alopecia, dry skin

Interactions

Nursing Considerations

Here are important nursing considerations when administering ARBs:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned contraindications to this drug (e.g. drug allergy, hypovolemia, renal impairment, etc.) to prevent potential adverse effects.
  • Obtain baseline status for weight, vital signs, overall skin condition, and laboratory tests like renal and hepatic function tests, and serum electrolyte to assess patient’s response to therapy.

Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of this drug for therapy:

Implementation with Rationale

These are vital nursing interventions done in patients who are taking ARBs:

  • Educate patient on importance of healthy lifestyle choices which include regular exercise, weight loss, smoking cessation, and low-sodium diet to maximize the effect of antihypertensive therapy.
  • Administer drug with food to prevent GI distress associated with drug intake.
  • Monitor renal and hepatic function tests to alert doctor for possible development of renal and/or hepatic failure as well as to signal need for reduced drug dose.
  • Provide comfort measures (e.g. quiet environment, relaxation techniques, etc.) to help patient tolerate drug effects.
  • Educate patient and family members about drug’s effect to the body and manifestations that would need reporting to enhance patient knowledge on drug therapy and promote adherence.

Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug therapy:

  • Monitor patient response to therapy through blood pressure monitoring.
  • Monitor for adverse effects (e.g. skin reactions, cough, headache, etc.)
  • Evaluate patient understanding on drug therapy by asking patient to name the drug, its indication, and adverse effects to watch for.
  • Monitor patient compliance to drug therapy.

Calcium-Channel Blockers


Description

  • Calcium-channel blockers as antihypertensive agents decrease blood pressure, cardiac workload, and myocardial consumption of oxygen.
  • Since these drugs can significantly decrease cardiac workload, they are effective in treatment of angina.

Therapeutic Action

  • These drugs inhibit the movement of calcium ions across myocardial and arterial muscle cell membranes. As a result, action potential of these cells are altered and cell contractions are blocked.
  • Resultant effects include: depressed myocardial contractility, slow cardiac impulse in conductive tissues, and arterial dilation and relaxation.

Indications

  • Like ACE inhibitors and ARBs, they can also be used alone for treatment of hypertension or in combination with other antihypertensive agents.
  • Extended-release preparations are usually indicated for hypertensions in adults.
  • Children: calcium-channel blockers is the drug group that is first considered in cases of hypertension in this age group that needs drug therapy.
  • Adults: these drugs are not allowed during pregnancy.
  • Older adults: are more susceptible to drug toxicity because of underlying conditions that would interfere with metabolism and excretion of drug. Renal and hepatic function should always be monitored.

Pharmacokinetics

Route Onset Peak Duration
Oral and extended release 30-60 min 6-11 h 12 h
T1/2: 5-7 h
Metabolism: liver
Excretion: urine

Contraindications and Cautions

  • Allergy to calcium-channel blockers. Prevent severe hypersensitivity reactions.
  • Heart block (sick sinus syndrome). Can be exacerbated by conduction-slowing effect of the drug.
  • Renal and hepatic impairment. Can alter metabolism and excretion of drugs which can increase the risk for toxicity.
  • Pregnancy and lactation. Can cause potential adverse effects to the fetus and should not be used unless the benefit to the mother clearly outweighs the risk to the fetus. It is not clear whether this drug can enter breast milk so another method of feeding is implemented for lactating mothers who are taking this drug.

Adverse Effects

  • CNS: headache, dizziness, light-headedness, fatigue
  • CV: hypotension, bradycardia, peripheral edema, heart block
  • GI: nausea, hepatic injury
  • EENT: rash, skin flushing

Interactions

  • Increased serum level and toxicity of cyclosporine if taken with diltiazem.
  • Grapefruit juice can increase serum level and toxicity of calcium-channel blockers.

Nursing Considerations

Here are important nursing considerations when administering calcium-channel blockers:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned contraindications to this drug (e.g. headache, rash, bradycardia, etc.) to prevent potential adverse effects.
  • Monitor cardiopulmonary status closely as the drug can cause severe effects on these two body systems.

Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of this drug for therapy:

Implementation with Rationale

These are vital nursing interventions done in patients who are taking calcium-channel blockers:

  • Educate patient on importance of healthy lifestyle choices which include regular exercise, weight loss, smoking cessation, and low-sodium diet to maximize the effect of antihypertensive therapy.
  • Monitor blood pressure and heart rate and rhythm to detect possible development of adverse effects.
  • Provide comfort measures for the patient to tolerate side effects (e.g. small frequent meals for nausea, limiting noise and controlling room light and temperature to prevent aggravation of stress which can increase demand to the heart, etc.)
  • Educate patient and family members about drug’s effect to the body and manifestations that would need reporting to enhance patient knowledge on drug therapy and promote adherence.
  • Emphasize to the client the importance of strict adherence to drug therapy to ensure maximum therapeutic effects.

Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug therapy:

  • Monitor patient response to therapy through blood pressure monitoring.
  • Monitor for presence of mentioned adverse effects.
  • Monitor for effectiveness of comfort measures.
  • Monitor for compliance to drug therapy regimen.
  • Monitor laboratory tests.

Vasodilators


Description

  • Direct vasodilators are used when the previous drugs mentioned are not effective.
  • These antihypertensive agents are reserved for severe hypertension and hypertensive emergencies.

Therapeutic Action

  • These antihypertensive agents exert their effect by acting directly on smooth muscles. Consequently, there will be muscle relaxation and vasodilation. Both of these will cause drop in blood pressure.

Indications

  • As mentioned, these drugs are only used for hypertension cases that do not respond to other drug therapies.
  • Nitroprusside is used in maintaining controlled hypotension during surgery.
  • Nitroprusside is administered intravenously; hydralazine is available for oral, intravenous, and intramuscular use; and minoxidil is available for oral use only.

Pharmacokinetics

Route Onset Peak Duration
IV 1-2 min Rapid 1-10 min
T1/2: 2 min
Metabolism: liver
Excretion: urine

Contraindications and Cautions

  • Allergy to direct vasodilators. Prevent severe hypersensitivity reactions.
  • Cerebral insufficiency. Can be exacerbated by drug’s action to cause sudden drop in blood pressure.
  • Peripheral vascular disease, CAD, heart failure, tachycardia. These conditions can be exacerbated by sudden drop in blood pressure.
  • Pregnancy and lactation. Can cause potential adverse effects to the fetus and should not be used unless the benefit to the mother clearly outweighs the risk to the fetus. The drug can enter the breast milk and can cause potential adverse effects to the neonate. If needed by lactating mothers, another method of feeding is instituted.

Adverse Effects

  • CNS: headache, dizziness, anxiety
  • CV: reflex tachycardia, heart failure, edema, chest pain
  • GI: nausea, vomiting, GI upset
  • EENT: rash, lesions (e.g. minoxidil is associated with abnormal hair growth.)
  • Nitroprusside is metabolized into cyanide so it can cause cyanide toxicity characterized by dyspnea, ataxia, loss of consciousness, distant heart sounds, and dilated pupil.
  • Nitroprusside suppresses iodine uptake which leads to development of hypothyroidism.

Interactions

  • Each drug in this group act differently on the body so each drug should be checked for potential drug-to-drug and drug-to-food interactions.

Nursing Considerations

Here are important nursing considerations when administering direct vasodilators:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned contraindications to this drug (e.g. drug allergy, CAD, cerebral insufficiency etc.) to prevent potential adverse effects.
  • Obtain baseline status for weight, vital signs, overall skin condition, and laboratory tests like renal and hepatic function tests, and serum electrolyte to assess patient’s response to therapy.

Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of this drug for therapy:

  • Decreased tissue perfusion related to changes in volume of blood pumped out by the heart
  • Acute pain related to GI distress, headache, and skin effects of the drug

Implementation with Rationale

These are vital nursing interventions done in patients who are taking vasodilators:

  • Educate patient on importance of healthy lifestyle choices which include regular exercise, weight loss, smoking cessation, and low-sodium diet to maximize the effect of antihypertensive therapy.
  • Monitor blood pressure and heart rate and rhythm closely to evaluate for effectiveness and ensure quick response if blood pressure falls rapidly or too much.
  • Provide comfort measures for the patient to tolerate side effects (e.g. small frequent meals for nausea, limiting noise and controlling room light and temperature to prevent aggravation of stress which can increase demand to the heart, etc.)
  • Monitor patient for any manifestations that could decrease fluid volume inside the body (e.g. vomiting, diarrhea, excessive sweating, etc.) to detect and treat excessive hypotension.
  • Educate patient and family members about drug’s effect to the body and manifestations that would need reporting to enhance patient knowledge on drug therapy and promote adherence.
  • Emphasize to the client the importance of strict adherence to drug therapy to ensure maximum therapeutic effects.

Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug therapy:

  • Monitor patient response to therapy through blood pressure monitoring.
  • Monitor for presence of mentioned adverse effects (e.g. hypotension, GI distress, skin reactions, etc.)
  • Monitor for effectiveness of comfort measures.
  • Monitor for compliance to drug therapy regimen.
  • Monitor laboratory tests.

Practice Quiz: Antihypertensive Agents


Quiz time! Just how much you’ve learned from our nursing pharmacology study guide for Antihypertensive Agents? Take the 5-item quiz below and find out!

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Questions


1. The three primary elements that determine the pressure in the cardiovascular system are heart rate, stroke volume, and:

A. Baroreceptors
B. Peripheral resistance
C. Renin-Angiotensin-Aldosterone System (RAAS)
D. All of the above

2. Untreated hypertension can result to which of the following:

A. Stroke
B. Renal failure
C. Loss of vision
D. All of the above

3. A student nurse was asked to take the blood pressure of a patient in the emergency room. The BP reads 140/90 mmHg. She would be correct to say that this BP belongs to ____________ classification.

A. Normal
B. Prehypertension
C. Class I Hypertension
D. Class II Hypertension

4. Which of the following medications will decrease the therapeutic effects of quinapril (Accupril)?

A. NSAIDs
B. Allopurinol
C. Antacids
D. All of the above

5. A patient receiving nitroprusside begun manifesting headache, distant heart sounds, imperceptible pulses, and shallow breathing. The nurse knows that these are signs of?

A. Reflex tachycardia
B. Hypothyroidism
C. Cyanide toxicity
D. Severe alteration of blood pressure

Answers and Rationale


1. Answer: B. Peripheral resistance.

Small arterioles help regulate blood pressure in a constant basis and are the most important factor affecting peripheral resistance. When small arterioles constrict, they are almost able to stop the flow of the blood. Their high responsiveness to sympathetic nervous stimulation cause them to constrict and increase blood pressure. Baroreceptors are pressure receptors located in the arch of the aorta and carotid arteries that send information to the brain when pressure increases. RAAS is a compensatory mechanism activated in the kidney when blood pressure falls.

2. Answer: D. All of the above.

The force of the blood propelled against blood vessels can damage their linings, making them susceptible to atherosclerosis and narrowing. When these happen, tiny vessels in the retina, kidneys, and brain can be destroyed leading to unresponsiveness of the system.

3. Answer: C. Class I Hypertension.

A category rating the severity of hypertension has been devised and the classifications of blood pressure are as follows: Normal – systolic: <120 mmHg; diastolic: <80; Prehypertension – systolic: 120-139; diastolic: 80-89; Class I Hypertension – systolic: 140-159; diastolic: 90-99; Class II Hypertension – systolic: less than or equal to 160; diastolic: less than or equal to 100.

4. Answer: A. NSAIDs.

Quinapril belongs to the class ACE inhibitors. NSAIDs are linked to decreased antihypertensive effects of ACE inhibitors. Allopurinol increases risk of hypersensitivity when combined with ACE inhibitors.

5. Answer: C. Cyanide toxicity.

Nitroprusside is metabolized into cyanide. Other manifestations of cyanide toxicity include pink color, loss of consciousness, and absence of reflexes.

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