Loop Diuretics
What is the MOA of loop diuretics?
*Have renal, cardiovascular, and metabolic effects:
- Act on the loop of Henle in the kidney to inhibit chloride and sodium resorption.
- Dilate blood vessels; reduced peripheral vascular resistance
- Treat edema
Name a commonly used osmotic diuretic.
Mannitol
Name 2 potassium-sparing diuretics.
- spironolactone (Aldactone)
- triamterene (Dyrenium)
When should patients be instructed to take their prescribed diuretic?
Take the medication in the morning to avoid interference with sleep patterns.
What electrolyte losses occur as a result of taking the loop diuretics?
- potassium
- sodium
- calcium (to a lesser extent)
What is the MOA of osmotic diuretics?
- works in the proximal tubule
- is nonabsorbable, so it pulls fluid into the renal tubules from the surrounding tissues
- only a slight loss of electrolytes, especially sodium
What is the MOA of potassium-sparing diuretics?
- Prevent potassium from being pumped into the tubules in the kidney, thereby preventing its secretion in the urine.
**This causes an increase in the potassium level.
- Also promote the excretion of sodium and water.
What should a diabetic patient watch for who is taking either a thiazide or loop diuretic?
They should monitor their blood glucose and watch for elevated levels.
**Note: Loop diuretics may cause blood glucose levels to increase due to the electrolyte imbalances, particularly low potassium levels, they may cause. Low potassium levels can impair the body's ability to effectively utilize insulin, resulting in higher blood sugar levels.
Name 2 loop diuretic drugs.
furosemide (Lasix)
bumetanide
What conditions are osmotic diuretics used for?
- early phase of acute renal failure
- reduce intracranial pressure
- treatment of cerebral edema
What are the indications for using spironolactone and triamterene?
- HTN
- reversing potassium loss caused by potassium-losing drugs
- prevention of cardiac remodeling in certain cases of HF
**Note: Remodeling is the change in the heart's size and shape that occurs in response to cardiac disease or cardiac damage.
What do patients need to be aware of when taking a diuretic?
They may experience orthostatic hypotension, so they should change positions slowly and rise slowly after sitting or lying.
What are some indications for taking loop diuretics?
- edema (due to HF or hepatic or renal disease)
- HTN
- increase renal excretion of calcium in patients with hypercalcemia
- HF due to diastolic dysfunction
What are the adverse effects of osmotic diuretics?
- convulsions
- thrombophlebitis
- pulmonary congestion
What adverse effects can occur with potassium-sparing diuretics?
- dizziness
- urinary frequency
- hyperkalemia
Name some adverse effects associated with loop diuretics.
- Dizziness, tinnitus, blurred vision
- Hypokalemia
- Hypotension
**NOTE: Pts often receive potassium supplements when taking furosemide to prevent hypokalemia.
How is Mannitol administered?
By intravenous (IV) infusion only.
What adverse effects should the nurse be aware of with spironolactone?
- gynecomastia
- amenorrhea
- irregular menses
- postmenopausal bleeding
Furosemide is the most commonly used loop diuretic. What conditions is it used for?
- pulmonary edema
- edema associated with heart failure
- liver disease
- ascites
- HTN
As a nurse, what should you know about the administration of mannitol?
It may crystallize when exposed to low temperatures, so the use of a filter is always required.
**NOTE: If the nurse notices crystals present in the IV bag or tubing, the solution should be discarded and restarted using a new bag of mannitol.
A patient is taking a potassium-sparing diuretic. Which drugs should they avoid taking?
- lithium (results in lithium toxicity)
- ACE inhibitors (results in hyperkalemia)
- potassium supplements (results in hyperkalemia)
A patient was taking mannitol for cerebral edema. How would the nurse know whether the medication was effective?
The patient would experience an increased level of consciousness.
Is it advisable for a pregnant woman to take spironolactone?
Spironolactone is a Pregnancy Category D drug. There is positive evidence of risk to the fetus in humans, but the potential benefits may outweigh the risks.