Ch 44 Drugs Acting on the Renin-Angiotensin-Aldosterone System
How does the RAAS raise BP?
"The RAAS, acting through angiotensin II, raises blood pressure through two basic processes: vasoconstriction and renal retention of water and sodium. Vasoconstriction raises BP by increasing total peripheral resistance; retention of water and sodium raises BP by increasing blood volume" (p. 485).
What are the primary indications for angiotensin II receptor blockers (ARBs)?
"The indications for ARBs are limited to: - hypertension - HF - diabetic neuropathy - prevention of CV events in patients at risk" (p. 482).
Why should lithium levels be monitored with ACE inhibitor use?
"ACE inhibitors can cause lithium to accumulate to toxic levels" (p. 489)
What are the actions of aldosterone?
"After being released from the adrenal cortex, aldosterone acts on distal tubules of the kidney to cause retention of sodium and excretion of potassium and hydrogen. Because retention of sodium causes water to be retained as well, aldosterone increases blood volume, which causes blood pressure to rise" (p. 484).
What electrolyte criteria is required to enhance aldosterone secretion?
"Aldosterone secretion is enhanced when sodium levels are low and when potassium levels are high" (p. 482).
How does angiotensin II work to release aldosterone?
"Angiotensin II acts on the adrenal cortex to promote synthesis and secretion of aldosterone. The adrenal cortex is highly sensitive to angiotensin II, and hence angiotensin II can stimulate aldosterone release even when angiotensin II levels are too low to induce vasoconstriction" (p. 482).
What are the most prominent actions of angiotensin II?
"Angiotensin II participates in all processes regulated by the renin-angiotensin-aldosterone system (RAAS). The most prominent actions of angiotensin II are: - vasoconstriction - stimulation of aldosterone release Both actions raise blood pressure. In addition, angiotensin II (as well as aldosterone) can act on the heart and blood vessels to cause pathologic changes in their structure and function" (p. 482).
What enzyme catalyzes the conversion of angiotensin I into angiotensin II?
"Angiotensin-converting enzyme (ACE) (or "kinase II"), located on the luminal surface of all blood vessels, catalyzes the conversion of angiotensin I (inactive) into angiotensin II (highly active)" (p. 484).
With which ACE inhibitor is neutropenia of highest concern?
"Neutropenia, with its associated risk of infection, is a rare but serious complication. Neutropenia is more common with captopril than with other ACE inhibitors. Patients should be informed about the early signs of infection (e.g., fever, sore throat) and instructed to report them immediately" (p. 489).
What molecule catalyzes the formation of angiotensin from angiotensinogen?
"Renin catalyzes the formation of angiotensin I from angiotensinogen. *Renin must be released into the blood in order to act" (p. 484).
What are the main therapeutic uses of angiotensin-converting enzyme (ACE) inhibitors?
"The ACE inhibitors have established roles in the treatment of: - hypertension - HF - diabetic neuropathy - MI - prevention of CV events in patients at risk" (p. 482).
The nurse is preparing discharge instructions for a client who was prescribed enalapril for treatment of hypertension. Which instruction is appropriate for the nurse to include in the client's teaching? A. Do not change to a standing position suddenly B. Lightheadedness is a common adverse effect that need not be reported C. The medication may cause a sore throat for the first few days D. Schedule blood tests weekly for the first two months
A. Enalapril is classified as an angiotensin-converting enzyme (ACE) inhibitor. It is used to treat hypertension and congestive HF. It can be used to treat a disorder of the ventricles. Angiotensin is a chemical that causes the arteries to become narrow. ACE inhibitors help the body produce less angiotensin, which helps the blood vessels relax and open up, which, in turn, lowers BP. Clients should be advised to change positions slowly to minimize orthostatic hypotension. A HCP should be notified immediately if the client is experiencing lightheadedness or feeling like he or she is about to faint, as this is a serious adverse effect. This medication does not cause a sore throat the first few days of treatment. Presently, there are no guidelines that suggest blood tests are required weekly for the first 2 months.
The nurse has just administered the initial dose of enalapril [Vasotec] to a newly admitted patient with hypertension. What is the priority nursing intervention over the next several hours? A. Monitor blood pressure. B. Check the heart rate. C. Auscultate lung sounds. D. Draw a potassium level.
A. First-dose hypotension is a serious potential adverse effect of ACE inhibitors, such as enalapril. Monitoring the blood pressure is the priority nursing intervention. If hypotension develops, the nurse will place the patient in the supine position and possibly increase intravenous fluids. The other interventions may be appropriate for this patient; however, in the hours immediately after the first dose of an ACE inhibitor, monitoring of the blood pressure is most important.
Captopril
ACE inhibitor
What is aldosterone released from?
Aldosterone is released from the adrenal cortex (p. 484)
-sartan
Angiotensin II receptor blocker (ARB)
The nurse is caring for a patient with bipolar disorder treated with lithium [Eskalith]. The patient has a new prescription for captopril [Capoten] for hypertension. The combination of these two drugs makes which assessment particularly important? A. Potassium level B. Lithium level C. Creatinine level D. Blood pressure
B. ACE inhibitors, such as captopril, can cause lithium accumulation. Lithium levels should be monitored on a regular basis. ACE inhibitors can cause hyperkalemia, renal insufficiency in some patients, and hypotension. However, the combination of lithium and captopril would not increase the risk of these effects.
The renin-angiotensin-aldosterone system plays an important role in maintaining blood pressure. Which compound in this system is most powerful at raising the blood pressure? A. Angiotensin I B. Angiotensin II C. Angiotensin III D. Renin
B. Angiotensin II is a potent vasoconstrictor. It participates in all the pathways regulated by the renin-angiotensin-aldosterone system. Angiotensin I is a precursor to angiotensin II; angiotensin III is formed by degradation of angiotensin II and is less potent. Renin catalyzes the conversion of angiotensinogen to angiotensin I.
A client is admitted to the hospital and benazepril is prescribed for hypertension. Which is an appropriate nursing action for clients taking this medication? A. Monitor the electroencephalogram (EEG) B. Assess for dizziness C. Administer the drug after meals D. Assess for dark, tarry stools
B. Dizziness may occur during the first few weeks of therapy until the client adapts physiologically to the medication. An EEG is unnecessary. Cardiac monitoring may be instituted because of possible dysrhythmias. Administering the drug after meals is unnecessary; however, if nausea occurs, the medication may be taken with food or at bedtime. The BP should be monitored before and after administration. Dark, tarry stools are not a side effect of benazepril.
A patient is prescribed lisinopril [Prinivil] 40 mg by mouth once a day for hypertension. For which therapeutic effect will the nurse monitor? A. Slowing of the heart rate B. Decrease in blood pressure C. Symptoms such as dizziness and fainting D. Pulse oximetry oxygen saturation of 100%
B. The therapeutic effect of ACE inhibitors is to reduce blood pressure in patients with hypertension. ACE inhibitors do not affect patients' heart rate. Dizziness and fainting are symptoms of hypotension. ACE inhibitors do not affect oxygen saturation.
The nurse is teaching a patient prescribed captopril [Capoten] for the treatment of hypertension. Which instructions should the nurse include? (Select all that apply.) A. Take the medication with food. B. Expect a sore throat and fever. C. Avoid potassium salt substitutes. D. A persistent dry cough may occur. E. Report difficulty in breathing immediately.
C, D, and E. Salt substitutes contain potassium and may increase the risk of hyperkalemia with ACE inhibitors. A persistent, dry, nonproductive cough may develop. Angioedema includes edema of the tongue, glottis, and pharynx that may cause difficulty breathing which requires immediate medical attention. Captopril [Capoten] must be taken at least one hour before meals. A sore throat and fever are not expected adverse effects. ACE inhibitors can lower white cell count and decrease the body's ability to fight an infection. Early signs of infection include fever and sore throat.
A patient is prescribed lisinopril [Prinvil] as part of the treatment plan for heart failure. Which finding indicates the patient is experiencing the therapeutic effect of this drug? A. + 2 edema of the lower extremities B. Potassium level of 3.5 mEq/L C. Crackles in the lungs are no longer heard D. Jugular vein distention
C. Because ACE inhibitors promote venous dilation, they provide the therapeutic effect of reducing pulmonary congestion and peripheral edema. Absence of previously heard crackles would be an indicator of effectiveness. Edema and jugular vein distention are manifestations of heart failure. A potassium level of 3.5 mEq/L is a normal value.
The nurse is caring for a patient with renal artery stenosis who has been prescribed benazepril [Lotensin]. Which laboratory result indicates an adverse effect of this drug? A. Potassium level of 3.2 mEq/L B. Blood glucose level of 180 mg/dL C. Serum creatinine level of 2.3 mg/dL D. Uric acid level of 10 mg/dL
C. Patients with bilateral renal artery stenosis are at increased risk for renal insufficiency and failure with angiotensin-converting enzyme (ACE) inhibitors, such as benazepril. ACE inhibitors do not typically cause hypokalemia, hyperglycemia, or hyperuricemia.
The nurse is evaluating the teaching done with a patient who has a new prescription for fosinopril [Monopril]. Which statement by the patient indicates a need for further teaching? A. "I can take this medicine with breakfast each morning." B. "I will call if I notice a rash or wheals on my skin." C. "I will use a salt substitute to lower my sodium intake." D. "I will call if I develop a bothersome cough."
C. Salt substitutes contain potassium and may increase the risk of hyperkalemia with ACE inhibitors, such as fosinopril. The patient should not take potassium supplements or use salt substitutes. The other statements are appropriate for this patient.
A patient is admitted to the hospital with a diagnosis of hypertension. The nurse understands that which medication works by preventing angiotensin II from binding with its receptor sites? A. Quinapril [Accupril] B. Aliskiren [Tekturna] C. Eplerenone [Inspra] D. Candesartan [Atacand]
D. Candesartan is an angiotensin II receptor blocker (ARB) and thus prevents the binding of angiotensin II at its receptor sites. Quinapril is an ACE inhibitor; aliskiren is a direct renin inhibitor, and eplerenone is a selective aldosterone receptor blocker.
What factors trigger the release of renin?
Decline in: - BP - blood volume - plasma sodium content - renal perfusion pressure (an especially important stimulus for renin release) (p. 484)
T/F ACE inhibitors are safe to take while pregnant.
F. "ACE inhibitors can injure the developing fetus during the second and third trimesters of pregnancy. Specific effects include hypotension, hyperkalemia, skull hypoplasia, pulmonary hypoplasia, anuria, renal failure (reversible and irreversible), and death. Women who become pregnant while using ACE inhibitors should discontinue treatment as soon as possible" (p. 488). ARBs can also cause fetal harm (p. 490).
T/F Captopril can be administered with meals.
F. Most oral ACE inhibitors can be administered with food. However, captopril and moexipril cannot and, thus, should be administered 1 hr before meals.
T/F All ARBs can be taken with or without food.
T. All ARBs are administered PO, and all may be taken with or without food.
What are the most prominent adverse effects of ACE inhibitors?
The most prominent adverse effects of ACE inhibitors are: - cough - angioedema (manifested as giant wheals and edema of the tongue, glottis, lips, eyes, and pharynx) - first-dose hypotension - hyperkalemia (p. 485, 488) Renal failure, fetal injury, and neutropenia can occur as well (p. 488-489)
