Pharmacology Module 10

What do diuretics do?

They increase fluid loss by increasing urine output

What are some indications for diuretics?

To lower blood pressure, decrease pulmonary edema and cerebral edema, promote adequate output, decrease localized fluid volume (ie glaucoma), and decrease generalized fluid volume (ie anasarca)

What are the potential adverse side effects of diuretics?

Electrolyte imbalances, dehydration and acid/base imbalance, hypotension (dependent on fluid volume loss)

What are the potential adverse side effects specific to loop diuretics, such as furosemide (Lasix)?

Hypokalemia, hyperuricemia, and hyperglycemia

What are the potential adverse side effects specific to the diuretic thiazide (hydrochlorothiazide/HCTZ)?

Hypokalemia, hyperuricemia, and hyperglcyemia

What are the potential adverse side effects specific to potassium-sparing diuretics, such as spironolactone (Aldactone)?

Hyperkalemia, gynecomastia (because of its steroid actions), erectile dysfunction and menstrual irregularities

What are the potential adverse side effects specific to the diuretic osmotic mannitol (Osmitrol)?

Convulsions, thrombophlebitis, pulmonary edema secondary to circulatory overload

What effect might hyperglycemia (caused by loop and thiazide diuretics) have on co-morbid conditions?

Complicates diabetes management

What effect might hyperuricemia (caused by loop and thiazide diuretics) have on co-morbid conditions?

Complicates gout management

What effect might hyopkalemia (caused by loop and thiazide diuretics) have on co-morbid conditions?

Increases risk of digoxin toxicity

What effect might hyperkalemia (caused by potassium-sparing diuretics) have on co-morbid conditions?

Additive hyperkalemia if taken with ACEIs or ARBs

How do you monitor the effectiveness of diuretics?

According to reason given:

If given for hypertension, BP should be controlled.

If given for pulmonary edema, breath sounds should be clear.

If given for glaucoma, intraocular pressure should decrease.

What are some drugs that can discolor the urine?

Triamterene (a potassium-sparing diuretic) may turn the urine blue.

Nitrofurantoin (a urinary antiseptic) may turn the urine a rust/brown color.

Rifampin (an antimycobacterial drug) may turn the urine orange.

Levodopa (an anti-parkinson's drug) may turn the urine dark yellow, orange, red, or brown.

What is a carbonic anhydrase inhibitor and how is it used?

A diuretic, used primarily to decrease ocular fluid in the treatment of glaucoma or when there is resistance to other diuretics.

Which class of diuretic has a rapid onset and blocks sodium reabsorption by the body?

Loop diuretics (used to decrease cardiac workload in heart failure)

Which class of diuretic has a rapid onset and pulls extra fluid into the nephron for elimination?

Osmotic diuretics (commonly used in head trauma and cases of intracranial pressure)

Which class of diuretics is very weak and blocks or inhibits aldosterone?

Potassium-sparing diuretics (typically used as an adjunct with other diuretics that cause potassium loss)

Which class of diuretics has moderate effectiveness and inhibits the reabsorption of sodium, potassium, and chloride?

Thiazide diuretics. (Not effective if there is significant renal dysfunction). First-choice role in management of HTN.

Which of the diuretics is most effective?

Loop diuretics and Osmotic diuretics. Both have a rapid onset.

Which class of diuretics does not use increased sodium excretion as a MOA?

Osmotic diuresis

Which class of diuretic is commonly recommended as the drug of choice in managing HTN?

Thiazide diuretics

Which diuretic classes may require adjustment of anti-diabetic drugs if given to patients with diabetes?

Loop diuretics and thiazide diuretics can cause blood glucose elevation

Which diuretic class must be given with a filter in order to avoid injection of intact crystals?

Osmotic diuretics

Which diuretic classes can precipate a gout attack?

Loop diuretics and thiazide diuretics can cause hyperuricemia (elevated uric acid levels)

How should diuretics be administered?

Diuretics should be taken in the morning. If ordered twice a day, the second dose should be taken in the early afternoon. By taking them earlier in the day, this eliminates sleep disruption and the likelihood of increased fall risk at night in the elderly.

Some diuretics (particularly loop and thiazides) cancause hypokalemia. What foods would you advise the patient to eat if this is the case?

High potassium foods, including dried apricots, avocados, bananas, cantaloupe, oranges, raisins, beans, and potatoes (with the skin)

If given for heart failure, assessment of what would indicate it's effectiveness?

Daily weights

If given for pulmonary edema, assessment of what would indicate it's effectiveness?

Improved lung sounds

If given for HTN, assessment of what would indicate it's effectiveness?

Decreased blood pressure

Why should patients taking diuretics be taught to not change positions or stand up too quickly?

Diuretics can cause orthostatic hypotension