NURS 3210 CH 28 PPT

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Questions and Answers

In which part of the nephron do potassium-sparing diuretics work?

Collecting ducts and distal convoluted tubules

How do potassium-sparing diuretics prevent potassium loss?

By preventing potassium from being pumped into the tubule

What is a unique adverse effect of spironolactone?

Gynecomastia

What type of diuretics inhibit tubular resorption of sodium, chloride, and potassium ions?

Thiazide and thiazide-like diuretics Signup and view all the answers

What is the primary site of action of thiazide and thiazide-like diuretics?

Distal convoluted tubule Signup and view all the answers

What is the effect of potassium-sparing diuretics on sodium and water?

Promote their excretion Signup and view all the answers

Which potassium-sparing diuretic is less effective in the long term?

Amiloride Signup and view all the answers

What medication class does metolazone belong to?

Thiazide-like diuretics Signup and view all the answers

What is the primary mechanism of action of osmotic diuretics in the proximal tubule?

Producing an osmotic effect, pulling water into the renal tubules from the surrounding tissues, and inhibiting tubular resorption of water and solutes. Signup and view all the answers

When administering a loop diuretic to a patient, what is the most important drug interaction to consider?

Lithium, as it can increase the risk of lithium toxicity. Signup and view all the answers

What is the name of the most commonly used loop diuretic?

Furosemide (Lasix) Signup and view all the answers

What is the primary effect of thiazide diuretics on the sequential nephron blockade?

Blockade of the sequential nephron Signup and view all the answers

Which type of diuretic is mannitol, and what is its mechanism of action?

Osmotic diuretic, producing an osmotic effect and pulling water into the renal tubules from the surrounding tissues. Signup and view all the answers

What is the potential interaction between loop diuretics and NSAIDs?

Increased risk of drug interactions. Signup and view all the answers

What is the primary effect of loop diuretics on the kidneys?

Increased urine production and diuresis. Signup and view all the answers

What is the name of another type of osmotic diuretic, besides mannitol?

Urea Signup and view all the answers

What is the primary effect of osmotic diuretics on glomerular filtration rate and renal plasma flow?

Increases Signup and view all the answers

What percentage of sodium and water is returned to the bloodstream from the filtered fluid in the proximal convoluted tubule?

60% to 70% Signup and view all the answers

What is the indication for using osmotic diuretics in patients with head trauma?

Reduces intracranial pressure or cerebral edema Signup and view all the answers

What is a potential adverse effect of osmotic diuretics?

Convulsions Signup and view all the answers

In which part of the nephron does the remaining 5% to 10% of sodium resorption take place?

distal convoluted tubule Signup and view all the answers

What is the administration route for mannitol (Osmitrol)?

Intravenous (IV) infusion only Signup and view all the answers

What is the mechanism of action of carbonic anhydrase inhibitors in the proximal tubules?

Inhibition of carbonic anhydrase, preventing the exchange of H+ ions with sodium and water Signup and view all the answers

What type of diuretic is acetazolamide (Diamox)?

Carbonic anhydrase inhibitor (CAI) Signup and view all the answers

What should the nurse do when noticing small crystals in the IV tubing during a mannitol (Osmitrol) infusion?

Discard the solution and obtain another bag of medication Signup and view all the answers

What is the primary indication for using osmotic diuretics in patients with acute renal failure (ARF)?

Treatment of patients in the early, oliguric phase Signup and view all the answers

What is the primary site of action of loop diuretics in the nephron?

ascending loop of Henle Signup and view all the answers

What is another indication for using osmotic diuretics?

To promote excretion of toxic substances Signup and view all the answers

Which type of diuretic is known to spare potassium in the kidneys?

Potassium-sparing diuretics Signup and view all the answers

What is the purpose of using a filter during the administration of mannitol (Osmitrol)?

To prevent crystallization of the solution Signup and view all the answers

What is the primary mechanism of action of osmotic diuretics?

Increase in osmotic pressure in the renal tubules, inhibiting sodium and water reabsorption Signup and view all the answers

What is the primary site of action of thiazide and thiazide-like diuretics in the nephron?

distal convoluted tubule Signup and view all the answers

What is the primary mechanism of action of thiazide and thiazide-like diuretics on arterioles?

Direct relaxation, leading to dilation Signup and view all the answers

What is the consequence of using thiazide diuretics in patients with severe renal impairment?

Ineffective, as creatinine clearance is less than 30-50 mL/min Signup and view all the answers

What is the primary indication for using thiazide and thiazide-like diuretics in patients with hypertension?

To lower peripheral vascular resistance and reduce blood pressure Signup and view all the answers

What is the adverse effect of thiazide and thiazide-like diuretics on the metabolic system?

Hypokalemia, hyperglycemia, hyperuricemia, and hypochloremic alkalosis Signup and view all the answers

What is the importance of assessing baseline fluid volume status, intake, and output in patients taking thiazide and thiazide-like diuretics?

To monitor for potential dehydration and electrolyte imbalances Signup and view all the answers

What is the reason for conducting a thorough patient history and physical examination before administering thiazide and thiazide-like diuretics?

To identify potential contraindications or cautions Signup and view all the answers

How do thiazide and thiazide-like diuretics differ from other types of diuretics in terms of their effectiveness in patients with renal impairment?

Metolazone remains effective in patients with creatinine clearance as low as 10 mL/min Signup and view all the answers

What is the role of thiazide and thiazide-like diuretics in the management of heart failure and hepatic cirrhosis?

Adjunctive therapy to reduce edema and fluid overload Signup and view all the answers

Study Notes

Diuretics

Classified according to their sites of action within the nephron, chemical structure, and diuretic potency
Types of diuretic drugs:
- Carbonic anhydrase inhibitors (CAIs)
- Loop diuretics
- Osmotic diuretics
- Potassium-sparing diuretics
- Thiazide and thiazide-like diuretics

Carbonic Anhydrase Inhibitors (CAIs)

Chemical derivative of sulfonamide antibiotics
Inhibit the activity of the enzyme carbonic anhydrase
Found in kidneys, eyes, and other parts of the body
Acetazolamide (Diamox) is the most commonly used CAI
Mechanism of action:
- Block the action of carbonic anhydrase, preventing the exchange of H+ ions with sodium and water
- Inhibition of carbonic anhydrase reduces H+ ion concentration in renal tubules
- Dilate arterioles by direct relaxation

Loop Diuretics

Most commonly used loop diuretic: Furosemide (Lasix)
Uses:
- Pulmonary edema
- Edema associated with heart failure (HF), liver disease, nephrotic syndrome, ascites, and hypertension
Important to determine if the patient is also taking lithium, as it can increase the risk of lithium toxicity

Osmotic Diuretics

Most commonly used osmotic diuretic: Mannitol (Osmitrol)
Mechanism of action:
- Work mostly in the proximal tubule
- Nonabsorbable, producing an osmotic effect
- Pull water into the renal tubules from the surrounding tissues
- Inhibit tubular resorption of water and solutes, producing rapid diuresis
Drug effects:
- Increases glomerular filtration rate and renal plasma flow
- Helps to prevent kidney damage during acute renal failure (ARF)
- Reduces intracranial pressure or cerebral edema associated with head trauma
- Reduces excessive intraocular pressure
Indications:
- Treatment of patients in the early, oliguric phase of ARF
- To promote excretion of toxic substances
- To reduce intracranial pressure
- Treatment of cerebral edema
Adverse effects:
- Convulsions
- Thrombophlebitis
- Pulmonary congestion

Potassium-Sparing Diuretics

Examples:
- Amiloride (Midamor)
- Spironolactone (Aldactone)
- Triamterene (Dyrenium)
Mechanism of action:
- Work in collecting ducts and distal convoluted tubules
- Interfere with sodium-potassium exchange
- Competitively bind to aldosterone receptors
- Block resorption of sodium and water usually induced by aldosterone
Drug effects:
- Prevent potassium from being pumped into the tubule, thus preventing its secretion
- Competitively block aldosterone receptors and inhibit their action
- Promote the excretion of sodium and water
Indications:
- Spironolactone and triamterene:
  - Hyperaldosteronism
  - Hypertension
  - Reversing potassium loss caused by potassium-losing drugs
  - Certain cases of HF: prevention of remodeling
- Amiloride:
  - Similar to spironolactone and triamterene, but less effective in the long term
Adverse effects:
- Body system:
  - CNS: dizziness, headache
  - GI: cramps, nausea, vomiting, diarrhea
  - Other: urinary frequency, weakness, hyperkalemia
- Spironolactone (Aldactone):
  - Gynecomastia
  - Amenorrhea
  - Irregular menses
  - Postmenopausal bleeding

Thiazide and Thiazide-Like Diuretics

Examples:
- Thiazide diuretics: hydrochlorothiazide (Esidrix, HydroDIURIL), chlorothiazide (Diuril)
- Thiazide-like diuretics: metolazone (Mykrox, Zaroxolyn), chlorthalidone (Hydone, Thalitone), indapamide (Lozol)
Mechanism of action:
- Inhibit tubular resorption of sodium, chloride, and potassium ions
- Action primarily in the distal convoluted tubule
- Result: water, sodium, and chloride are excreted, and potassium is also excreted to a lesser extent
Drug effects:
- Lowered peripheral vascular resistance
- Depletion of sodium and water (and potassium)
- Thiazides should not be used if creatinine clearance is less than 30 to 50 mL/min (normal is 125 mL/min)
- Metolazone remains effective to a creatinine clearance of 10 mL/min
Indications:
- Hypertension (one of the most prescribed group of drugs for this)
- Edematous states
- Idiopathic hypercalciuria
- Diabetes insipidus
- Adjunct drugs in management of heart failure and hepatic cirrhosis
Adverse effects:
- Body system:
  - CNS: dizziness, headache, blurred vision
  - GI: anorexia, nausea, vomiting, diarrhea
  - Genitourinary: impotence
  - Hematologic: jaundice, leukopenia
  - Integumentary: dizziness, headache, blurred vision
  - Metabolic: hypokalemia, hyperglycemia, hyperuricemia, hypochloremic alkalosis

Nursing Implications

Perform a thorough patient history and physical examination
Assess baseline fluid volume status, intake and output, serum electrolyte values, weight, and vital signs (especially postural blood pressure)
Assess for disorders that may contraindicate or necessitate cautious use of these drugs

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Description

This quiz tests your knowledge of diuretics, including thiazide, loop diuretics, and nonsteroidal antiinflammatory drugs, as well as their uses and indications.