Medications Affecting Fluid Balance

What are the major subclasses of Diuretic Drugs?

• Thiazide-like diuretics

• Loop diuretics

• Potassium-sparing diuretics

• carbonic anhydrase inhibitors

• Osmotic diuretics

What is the main site of action that loop diuretics work at?

Thick ascending limb of loop of Henle

What is the main site of action that thiazide diuretics work at?

Distal convoluted tubule

What is the main site of action that carbonic anhydrase inhibitors work at?

Proximal collecting tubule

What is the main site of action that potassium-sparing diuretics work at?

Collecting duct

What is the main site of action that osmotic diuretics work at?

Proximal collecting tubule and descending loop of henle

What is the prototype for thiazide-type diuretics?

Hydrochlorothiazide

What is the drug of choice for most patients who need diuretic therapy, especially long-term?

Thiazide-type diuretics (hydrochlorothiazide)

• diuretic of choice for mild to moderate hypertension

• diuretic of choice for long term management of heart failure

What is the mechanism of action for thiazide-type diuretics (hydrochlorothiazide)

• Decrease reabsorption of sodium, chloride, and bicarbonate in distal convoluted tube

• Prevents the reabsorption of water at site (if no Na+ going back into blood and it stays in urine)

• Promotes diuresis when renal function is not impaired

  • when renal function impaired, need to use different type of diuretic

What are the uses/indications of thiazide-type diuretics (hydrochlorothiazide) ?

• Mild to moderate hypertension

• Long term management of heart failure

• Edema associated with nephrotic syndrome (happens most in peds)

What are the responsibilities of the nurse when giving thiazide-type diuretics (hydrochlorothiazide)?

• Assess for effect

• Monitor I&O

• Do not give if Anuria - if not creating urine and renal function is that impaired, do not give

• Cross reactivity with sulfonamides (chemically related) - keep in mind if pt has allergy to sulfonamides

When should you not give a patient thiazide-type diuretics (hydrochlorothiazide)?

If they have renal impairment and if they have anuria

What allergy should you assess before giving a patient thiazide-type diuretics (hydrochlorothiazide)?

Sulfonamides - there is cross reactivity with sulfonamides

What are some side effects of thiazide-type diuretics (hydrochlorthiazide)?

• Hypersensitivity

• Hypotension (bc getting rid of fluid), weakness, dizziness

• Diarrhea, constipation (GI effects)

• Electrolyte imbalances (monitor):

  • hyponatremia, hypokalemia (n/v; general weakness), hypochloremia

What education should be given when giving patients thiazide-type diuretics (hydrochlorothiazide)?

• Take as prescribed

• Keep follow-up appointments

• Monitor for side effects (Especially signs of electrolyte imbalances and hypotension)

What is the prototype for loop diuretics?

Furosemide

Why are loop diuretics (Furosemide) considered alternate agents?

Alternate agents because thiazide-type diuretics preferred for more long-term care, whereas loop diuretics preferred in acute illness/critically ill plts

Are loop diuretics used for long term care or acutely ill patients?

Acutely ill

What is the mechanism of action for loop diuretics (furosemide)?

• Block the chloride pump in the ascending loop of Henle

  • this blocks reabsorption of sodium and chloride

  • causes significant diuresis even with severe renal impairment

What are the uses/indications of loop diuretics (furosemide)?

• Emergent need for rapid mobilization of fluid

  • Acute pulmonary edema

• Heart failure

• Hepatic and renal disease

What are the responsibilities of the nurse when giving loop diuretics (furosemide)?

• Monitor electrolyte levels (particularly K+)

• Not given if anuric

• Cross reactivity with sulfonamides

• Avoid during pregnancy bc can decrease blood flow through placenta

Similar to thiazide-type diuretics, you loop diuretics have cross reactivity with what?

Sulfonamides

Similar to thiazide-type diuretics, you cannot give a patient loop diuretics if they are what?

Anuric

Why should loop diuretics (furosemide) be avoiding during pregnancy?

They can decrease blood flow through the placenta

Loop diuretics (furosemide) severely decrease what?

Potassium

What are the side effects of loop diuretics (furosemide)?

• Dehydration

• Electrolyte imbalances: hypokalemia, hyponatremia, hypocholermia, decrease in calcium and magnesium levels

• Hypotension

• Ototoxicity

• Hyperglycemia

• Hyperuricema

What education should be given to patients taking loop diuretics (furosemide)?

• Take it in the morning

• Stand up slowly

• Monitor blood pressure and weight daily

• Report muscle weakness, cramps, palpitations, or unusual fatigue — indications of hypokalemia

• Report excessive thirst, dry mouth

• Keep appointments for labs

What is the prototype for carbonic anhydrase inhibitors?

Acetazolamide

Carbonic anhydrase inhibitors (acetazolamide) are usually used as main diuretics or adjunct to other diuretics?

Adjunct to other diuretics when more intense diuresis is needed

• can also be used for metabolic alkalosis

What is the mechanism of action for carbonic anhydrase inhibitors (acetazolamide)?

• Blocs the effects of carbonic anhydrase; slows down the movement of hydrogen ions

• More sodium and bicarbonate are lost in the urine, resulting in mild diuresis and decreased pH

What are the uses/indications of carbonic anhydrase inhibitors (acetazolamide)?

• Edema — adjuncts to other diuretics

• Metabolic alkalosis (because it decreases pH)

• Prevention/treatment of acute mountain sickness

• Glaucoma

What are the responsibilities of the nurse when giving carbonic anhydrase inhibitors (acetazolamide)?

• monitor fluid and electrolyte imbalances (hypokalemia, can cause hyponatremia too)

• Monitor acid-base status/bicarbonate

• Monitor renal function

• Assess fluid status

• Monitor for kidney stones (known side effect)

• Sulfonamide derivative (if pt has sulfonamide allergy, likely want to avoid use)

What are some side effects of carbonic anhydrase inhibitor (acetazolamide)?

• metabolic acidosis

• hypokalemia

• hyponatremia

• dehydration

• paresthesia of extremities

• GI upset

• Kidney stones

• Drug-to-drug interactions - salicylates and lithium

What drug interactions do carbonic anhydrase inhibitors (acetazolamide) have?

Salicylates and lithium

What education should patients taking carbonic anhydrase inhibitors (acetazolamide) be given?

• Take medication in the morning

• Maintain adequate hydration

• Report weakness, fatigue, muscle cramps, palpitations, persistent nausea/vomiting - can indicate hypokalemia

What is the prototype for potassium-sparing diuretics?

Spironolactone

Potassium-sparing diuretics (spironolactone) are weaker diuretics and cause hypo or hyperkalemia in comparison to other diuretics?

Hyperkalemia

What is the mechanism of action for potassium sparing diuretics (spironolactone)?

• Block the actions of aldosterone in the distal tubule

• Causes a loss of sodium while retaining potassium

What are the uses/indications of potassium-sparing diuretic (spironolactone)?

• Heart failure

• Adjuncts with thiazide or loop diuretics

• Patients who are at risk for hypokalemia (can help balance loss of K+ with loop diuretics)

What are the responsibilities of the nurse when giving potassium-sparing diuretics (spironolactone)

• Monitor electrolyte levels (especially potassium)

• Monitor BP and input and output

• Weigh patients daily (to monitor fluid status)

• Monitor ECG

• Ensure patient not pregnant (can cause fetal harm)

What are some side effects of potassium-sparing diuretic (spironolactone)?

• Hyperkalemia

• Deepened voice (because works on hormone aldosterone), impotence, gynecomastia, hirutism

• Drug-to-drug interactions with salicylates — decreases diuretic effect

The interaction between salicylates and potassium sparing diuretics (spironolactone) has what effect?

Decreases diuretic effect

What education should be given to patients when administering potassium-sparing diuretics (spironolactone)?

• Avoid salt substitutes or foods high in potassium (bc causes hyperkalemia)

• Monitor BP at home

• Keep a log of BP and weight

• Report cramps, diarrhea, and thirst

What is the prototype for osmotic diuretics?

Mannitol

What is the mechanism of action for osmotic diuretics (mannitol)?

• Raise serum osmolality (concentration)

• Not reabsorbed in renal tubules, so →

  • pulls water into the renal tubule without sodium loss

*Base of mannitol is glucose, so it’s a high amount of glucose and that’s how it affects fluid balances through osmosis with higher concentration of glucose → doesn’t affect sodium at all

What are the uses/indication of osmotic diuretics (mannitol)?

• Increased intracranial pressure (ICP) — this is what it is used more for but it is still a diuretic

• Acute renal failure due to shock, drug overdose, or trauma

• Hyponatremia

What are the responsibilities of the nurse when giving osmotic diuretics (mannitol)?

• Use with caution in patients with heart failure

• Use a filter need - it crystalizes (glucose can clump into sugar crystals, use filter to filter out crystals)

• Monitor daily weight, I&O, and serum electrolytes

• Monitor BP

• Monitor for increased ICP, metabolic acidosis

What are the side effects of osmotic diuretics (mannitol)?

• Hypokalemia

• Hypovolemia

• Metabolic acidosis

• Nausea, vomiting, hypotension, light-headedness, confusion, headache

What education should be given to patients taking osmotic diuretics (mannitol)?

• Get up slowly, if dizziness, sit or lie down

• Monitor blood pressure

• Report signifiant weigh loss, lightheadedness, GI distress, or general weakness

• Almost exclusively given in critical care at hospital

What is the safest range for potassium levels?

3.5-5.0mEq/L

Potassium at what levels can be life threatening?

6.5 or 2.5

What are some signs of increased potassium?

Increased irritability, diarrhea, ECG changes

What are some signs of decreased potassium?

Weakness, decreased reflexes, dysrhythmias, ECG changes