10 Questions
What is the primary mechanism of action of thiazides in the kidney?
Impairment of Na+ and Cl- reabsorption in the early distal tubule
What is a common adverse effect of loop diuretics?
Hypokalemia
Which of the following diuretics is used to treat calcium nephrolithiasis?
Thiazides
What is the mechanism of action of spironolactone?
Antagonism of aldosterone at intracellular cytoplasmic receptor sites
What is a common adverse effect of thiazides?
Hypokalemia
What is the primary effect of osmotic diuretics on the body?
Increased water excretion
What is a common adverse effect of spironolactone?
Gynecomastia
Why should potassium-sparing diuretics be used with caution in patients with renal dysfunction?
Risk of hyperkalemia
What is the primary mechanism of action of carbonic anhydrase inhibitors?
Inhibition of carbonic anhydrase
What is a potential consequence of using osmotic diuretics?
Dehydration
Study Notes
Thiazides (Low Ceiling Diuretics)
- Impair Na+ and Cl- reabsorption in the early distal tubule, increasing Ca2+ reabsorption and K+ excretion
- Increase urinary excretion of Na+, Cl-, K+, and water, reducing ECF volume, cardiac output, and blood pressure
- Therapeutic uses: treatment of hypertension, mild edema, and calcium nephrolithiasis
- Adverse effects: hypokalemia, hyperuricemia, hyperglycemia, and hyperlipidemia
Loop Diuretics (Furosemide, Bumetanide, Torsemide, Ethacrynic acid)
- Inhibit the apical Na+-K+-2Cl- cotransporter in the thick ascending limb of the loop of Henle
- Therapeutic effects: treatment of severe edema, pulmonary edema, acute renal failure, and hypercalcemia
- Adverse effects: profound ECFV depletion, hypokalemia, metabolic alkalosis, hypomagnesemia, hypocalcemia, hyperuricemia, and ototoxicity
Potassium-Sparing Diuretics
- Mechanisms of action:
- Spironolactone: antagonizes aldosterone at intracellular cytoplasmic receptor sites, preventing Na+ reabsorption and K+ and H+ secretion
- Triamterene and amiloride: block Na+ transport channels, decreasing Na+/K+ exchange
- Therapeutic uses: induction of diuresis, treatment of secondary hyperaldosteronism, heart failure, resistant hypertension, ascites, and polycystic ovary syndrome
- Adverse effects: gastric upset, gynecomastia, menstrual irregularities, hyperkalemia, nausea, lethargy, and mental confusion
Osmotic Diuretics (Mannitol, Urea)
- Mechanism of action: increase osmolarity of tubular fluid, resulting in osmotic diuresis
- Therapeutic uses: treatment of patients with increased intracranial pressure or acute renal failure due to shock, drug toxicities, and trauma
- Adverse effects: extracellular water expansion and dehydration, hyponatremia, and hypernatremia
Carbonic Anhydrase Inhibitors (Acetazolamide)
- Mechanism of action: inhibit carbonic anhydrase in the proximal tubular epithelium, decreasing ability to exchange Na+ for H+
- Result: mild diuresis, increased urinary pH, and hyperchloremic metabolic acidosis
- Therapeutic uses: treatment of glaucoma, mountain sickness, and idiopathic intracranial hypertension
Understand the mechanism of action of Thiazides, a type of low ceiling diuretic, and their therapeutic uses in treating hypertension, mild edema, and calcium nephrolithiasis. Learn about their adverse effects as well.
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