Session 4: Diuretics Flashcards
week 1
What is a diuretic?
A drug that alters renal mechanisms that form urine to increase the volume of urine and extent of sodium excreted.
Define diuresis.
The secretion and passage of large amounts of urine.
What is natriuresis?
The excretion of sodium in the urine.
What is a natriuretic drug?
A drug that increases the ratio of sodium excreted in the urine by preventing sodium reabsorption.
What are the implications of fluid loss caused by diuretics?
It has implications for various disease states.
In heart failure, why are diuretics administered?
To control pulmonary and peripheral symptoms of fluid overload, and signs of congestion.
Which diuretics are preferred in heart failure?
Loop diuretics are preferred.
What diuretics may be used for mild heart failure?
Thiazide diuretics.
What role does spironolactone play in heart failure?
It manages Class III & IV heart failure.
Are diuretic doses higher in heart failure or hypertension?
Diuretic doses are generally higher in heart failure than in hypertension.
What is required for diuretics to lower blood pressure in hypertension?
Some persistent volume depletion is required.
Why are once daily loop diuretics usually inadequate for hypertension?
Because initial sodium loss is quickly restored throughout the remainder of the day.
What are the three major groups of diuretics?
- Loop diuretics
- Thiazides
- Potassium-sparing agents
What is sequential nephron blockade?
The concept that each type of diuretic acts at a different site in the nephron.
What is the action of loop diuretics?
They provide superior fluid clearance for the same degree of natriuresis in thiazide and potassium-sparing diuretics.
Name three loop diuretics.
- Furosemide
- Ethacrynic acid
- Bumetanide
What is the pharmacologic effect of loop diuretics?
They inhibit the Na+/K+/2Cl- co-transporter, leading to loss of chloride, sodium, potassium, and hydrogen ions in urine.
What is the plasma half-life of furosemide?
1.5 hours.
When does diuresis peak after an oral dose of furosemide?
1 - 1.5 hours after oral dose.
What are the indications for intravenous furosemide?
- Severe heart failure
- Acute pulmonary edema
- Acute MI with clinical failure
- Hypertensive crisis if fluid overload is present
What are the contraindications for furosemide?
- Anuria
- Hypersensitivity to furosemide or sulfonimides
- Hypokalemia or electrolyte depletion
List some adverse effects of furosemide.
- Hypokalemia
- Hyponatremia
- Hypochloremic metabolic alkalosis
- Hypovolemia and Hypotension
- Hyperuricemia
- Diuretic-induced glucose intolerance
- Dehydration
What drug interactions are associated with furosemide?
- NSAIDs like Ibuprofen, Indomethacin, Naproxen lessen the diuretic response
- Antidiabetics decrease hypoglycemic effects
- Aminoglycoside antibiotics precipitate ototoxicity
What do thiazide diuretics inhibit?
Reabsorption of Na+ and Cl- in the more distal part of the nephron.
