Diuretics Overview

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Questions and Answers

What is the primary effect of carbonic anhydrase (CA) inhibitors on diuresis?

They have limited effect due to only affecting 20-25% of Na+ reabsorption. (correct)

They induce diuresis by inhibiting 99% of CA enzyme.

They primarily increase the acidity of urine.

They enhance Na+ reabsorption.

What physiological change can occur due to prolonged use of CA inhibitors?

Reduced urine alkalinity.

Enhanced kidney function.

Increased blood alkalinity.

Metabolic acidosis. (correct)

Which of the following drugs was the first carbonic anhydrase inhibitor that is orally effective?

Dichlorphenamide.

Methazolamide.

Acetazolamide. (correct)

Brinzolamide.

For what purpose is Methazolamide designed?

To decrease polarity for better ocular fluid penetration. Signup and view all the answers

Which of the following uses of CA inhibitors is most common?

Reducing intraocular pressure in glaucoma. Signup and view all the answers

What characterizes Dorzolamide and Brinzolamide compared to other CA inhibitors?

They are topically administered and more water-soluble. Signup and view all the answers

What is a notable side effect of non-selective CA inhibitors?

Inhibition of multiple CA isozymes in other tissues. Signup and view all the answers

What is the primary role of carbonic anhydrase (CA) in the nephron?

To facilitate Na+ reabsorption by exchanging with H+. Signup and view all the answers

What is the primary effect of diuretics on electrolyte levels?

Increase the excretion of sodium and chloride ions Signup and view all the answers

Which class of diuretics inhibits carbonic anhydrase within the proximal convoluted tubules?

Carbonic Anhydrase Inhibitors Signup and view all the answers

What is a common reason for combining potassium-sparing diuretics with other diuretics?

To prevent hypokalemia caused by other diuretics Signup and view all the answers

Which of the following statements about diuretics is true?

Diuretics increase urine formation without impacting glucose levels Signup and view all the answers

What critical role does carbonic anhydrase play in diuretic action?

It facilitates the reabsorption of sodium. Signup and view all the answers

Which factor is important for determining the efficacy of a diuretic?

The site of action of the diuretic Signup and view all the answers

What distinguishes arylamine sulfonamide drugs from non-arylamine sulfonamide drugs?

Their structural composition and potential for allergic reactions Signup and view all the answers

Which of the following is NOT a characteristic feature of diuretics?

Affect reabsorption of glucose Signup and view all the answers

What condition can be countered by potassium supplements when using certain diuretics?

Hypokalemia Signup and view all the answers

Which diuretic is known to be 50-fold more potent than furosemide?

Bumetanide Signup and view all the answers

Which of the following diuretics does not increase phosphate or bicarbonate excretion?

Torsemide Signup and view all the answers

Which potassium-sparing diuretic was discovered first?

Spironolactone Signup and view all the answers

What is the most serious side effect associated with amiloride and triamterene?

Hyperkalemia Signup and view all the answers

Ethacrynic acid is unique among loop diuretics because it is:

Not a sulfonamide derivative Signup and view all the answers

What effect does torsemide have on the kidneys compared to furosemide and bumetanide?

Does not act on the proximal tubule Signup and view all the answers

How long does orally administered ethacrynic acid take to exert its effect?

1 hour Signup and view all the answers

What is the effect of saturating the double bond between C3 and N4 in diuretic compounds?

Increases diuretic activity by tenfold Signup and view all the answers

Which of the following groups of substitutions at C3 increases potency and lipid solubility?

Haloalkyl groups Signup and view all the answers

What is one of the primary mechanisms of action of thiazide-like diuretics?

Inhibit the Na+/Cl- symporter Signup and view all the answers

How do high-ceiling (loop) diuretics differ from thiazide diuretics in terms of diuretic effect?

They produce a significantly higher peak diuretic effect Signup and view all the answers

What is one characteristic of furosemide compared to thiazide diuretics?

It has a greater saluretic effect Signup and view all the answers

What role does protein binding play in thiazide-like diuretics?

It contributes to their longer duration of action Signup and view all the answers

Which ion is primarily excreted by furosemide?

Sodium ions (Na+) Signup and view all the answers

What characterizes osmotic diuretics in their function?

They increase the excretion of water and electrolytes through high water solubility. Signup and view all the answers

Which type of diuretic can be effective when GFR falls below 40 mL/min?

Thiazide-like diuretics Signup and view all the answers

Which of the following is a commonly used osmotic diuretic?

Mannitol Signup and view all the answers

How do aquaretics differ from traditional diuretics?

They increase water excretion without losing electrolytes. Signup and view all the answers

What triggers the release of antidiuretic hormone (ADH)?

Decreased blood pressure and elevated plasma osmolality. Signup and view all the answers

What is the function of V2 receptors in the kidney?

They enhance water reabsorption in the collecting tubule. Signup and view all the answers

Why is demeclocycline preferred over lithium for ADH interference?

Demeclocycline has fewer adverse effects than lithium. Signup and view all the answers

Which of the following agents is available only for intravenous use?

Conivaptan Signup and view all the answers

What is a primary concern for using ADH receptor antagonists?

They can lead to significant electrolyte imbalances. Signup and view all the answers

Study Notes

Diuretics

Diuretics increase urine production by increasing the excretion of electrolytes (sodium, chloride) and water.
They do not affect the excretion of protein, vitamins, glucose, or amino acids.
Carbonic Anhydrase (CA) inhibitors block CA in the proximal convoluted tubules (PCT).
CA inhibitors limit hydrogen ion availability for sodium reabsorption, thus reducing sodium reabsorption.
They have limited diuretic efficacy as they affect only 20-25% of sodium reabsorption.
They are not highly efficacious diuretics.
Prolonged use can lead to alkaline urine and acidic blood (metabolic acidosis).
They are primarily used to treat glaucoma, by reducing aqueous humor formation.
They are also used to alkalinize urine, reduce metabolic alkalosis, and prevent acute mountain sickness.
While CA inhibitors contain sulfonamide groups, allergies to other sulfonamide-containing drugs are not common.
Thiazide-like diuretics are structurally diverse sulfonamide derivatives that do not contain the benzothiadiazine ring.
They have similar actions and side effects as thiazide diuretics.
They have a longer duration of action, due to protein binding and/or binding to carbonic anhydrase in red blood cells.
High-ceiling or loop diuretics are more efficacious than other diuretics.
They are called high-ceiling diuretics because they produce a greater diuretic effect than other diuretics.
They are called loop diuretics because they act on the loop of Henle.
Loop diuretics inhibit the sodium/potassium/2 chloride symporter (cotransport system).
They have a rapid onset (~30 minutes) and short duration of action (~6 hours).
Furosemide is the most commonly used loop diuretic.
Loop diuretics can cause hypokalemia, hypocalcemia, hyperuricemia, glucose intolerance, and increased serum lipids.
Potential side effects include ototoxicity (reversible) and gastrointestinal effects.
Potassium-sparing diuretics are used to prevent potassium loss caused by other diuretics.
They are generally weak diuretics but are often combined with other diuretics.
Amiloride and triamterene block sodium channels in the distal convoluted tubule (DCT) and collecting duct (CD).
This action reduces sodium reabsorption and potassium secretion.
Amiloride is more potent than triamterene.
The most serious side effect is hyperkalemia.
Osmotic diuretics are low molecular weight compounds that are freely filtered by the kidneys.
Once in the renal tubules, they are not reabsorbed due to their high water solubility.
They increase the intraluminal osmotic pressure, leading to water and electrolyte excretion, causing electrolyte disturbances (hypernatremia, hyperkalemia).
The most commonly used osmotic diuretic is mannitol, which is administered intravenously due to poor oral absorption.
Other osmotic diuretics include sorbitol, isosorbide, sugars (glucose and sucrose), and urea.

Aquaretics

Aquaretics increase urine production without electrolyte loss.
They are preferred over diuretics for treating hyponatremia.
Antidiuretic hormone (ADH, or vasopressin) antagonists block the action of ADH, leading to increased water excretion.
They can be used to treat hyponatremia (low sodium blood levels).
ADH is released from the posterior pituitary gland in response to decreased blood pressure and increased blood osmolarity.
ADH acts on the collecting tubule of the kidney to increase water permeability and absorption.
Demeclocycline, a tetracycline antimicrobial, and lithium are nonselective ADH antagonists.
Newer selective ADH antagonists are called vaptans.
Conivaptan is a nonselective vaptan that is FDA-approved for intravenous administration only.
Tolvaptan, lixivaptan, and satavaptan are selective V2 receptor antagonists approved for oral administration.
Tolvaptan is FDA-approved, while lixivaptan and satavaptan are under clinical investigation.

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Description

This quiz explores the function and characteristics of diuretics, particularly focusing on Carbonic Anhydrase inhibitors and their medical applications. Understand their mechanism of action, efficacy, and potential side effects. Perfect for students and professionals in pharmacology and medicine.