Diuretics and Salt Excretion

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Questions and Answers

Which type of diuretic acts mainly on the cortical region of the ascending loop of Henle and the distal convoluted tubule?

Carbonic anhydrase inhibitors

Loop diuretics

Thiazides (correct)

K-Sparing diuretics

What is the effect of thiazide diuretics on urinary sodium chloride excretion?

No effect

Decreased

Variable

Increased (correct)

What is a common side effect of thiazide diuretics?

Hypernatremia

Hyperchloremia

Hypokalemia (correct)

Hypocalcemia

Which of the following conditions is NOT an indication for thiazide diuretic therapy?

Chronic kidney disease Signup and view all the answers

What is the effect of thiazide diuretics on urinary calcium excretion?

Decreased Signup and view all the answers

Which type of diuretic acts on the proximal convoluted tubules?

Carbonic anhydrase inhibitors Signup and view all the answers

What is the effect of thiazide diuretics on blood volume and GFR in nephrogenic diabetes insipidus?

Decrease blood volume and GFR Signup and view all the answers

Which of the following is a metabolic effect of thiazide diuretics?

Metabolic alkalosis Signup and view all the answers

Which of the following loop diuretics has a higher potency and consistently high oral bioavailability?

Bumetanide Signup and view all the answers

What is the primary mechanism of action of potassium-sparing diuretics?

Interfere with sodium-potassium exchange in the distal convoluted tubule Signup and view all the answers

Which loop diuretic is most likely to cause deafness?

Ethacrynic Acid Signup and view all the answers

What is a common side effect of potassium-sparing diuretics?

Hyperkalemia Signup and view all the answers

Which potassium-sparing diuretic does not bind to aldosterone receptors?

Triamterene Signup and view all the answers

What is the mode of action of amiloride?

Directly inhibits sodium influx in the cortical collecting tubule Signup and view all the answers

What is a clinical use of amiloride?

Treatment of heart failure Signup and view all the answers

What is a gastrointestinal side effect of potassium-sparing diuretics?

Cramps Signup and view all the answers

What is the primary mechanism of action of triamterene?

Direct inhibition of sodium influx in the cortical collecting tubule (CCT) Signup and view all the answers

What is a common adverse effect of spironolactone?

Hyperkalemia Signup and view all the answers

What is the indication for spironolactone in certain cases of heart failure?

Hyperaldosteronism Signup and view all the answers

What is the mechanism of action of ADH in the collecting tubule?

Facilitation of water reabsorption by increasing cAMP Signup and view all the answers

What is a common adverse effect of ADH agonists?

Water overload Signup and view all the answers

What is the difference between spironolactone and its analog?

The analog has greater selectivity for the mineralocorticoid receptor Signup and view all the answers

What is the primary mechanism of action of Quinolone antibiotics?

Inhibiting bacterial DNA replication and transcription Signup and view all the answers

Which of the following is a contraindication for the use of Fluoroquinolones?

Pregnancy Signup and view all the answers

What is the main adverse effect of Methenamine?

Gastrointestinal tract Signup and view all the answers

What type of bacteria are Quinolones highly effective against?

Gram-negative bacteria Signup and view all the answers

Which of the following is a side effect of Fluoroquinolones?

Nausea and vomiting Signup and view all the answers

Which generation of Fluoroquinolones includes Moxifloxacin?

4th generation Signup and view all the answers

What is the effect of Quinolones on DNA?

All of the above Signup and view all the answers

What is the role of DNA gyrase and topoisomerase in bacterial DNA?

They help in DNA replication and transcription Signup and view all the answers

What is the mechanism of action of loop diuretics in the thick ascending limb (TAL)?

Inhibit Na+/K+/2Cl- pump Signup and view all the answers

Which of the following thiazide diuretics is most commonly used?

Hydrochlorothiazide Signup and view all the answers

What is the effect of loop diuretics on uric acid secretion?

Interfere with uric acid secretion Signup and view all the answers

Which of the following is a characteristic of indapamide?

Lipid soluble Signup and view all the answers

What is the effect of loop diuretics on Ca++ reabsorption?

Decrease passive Ca++ reabsorption Signup and view all the answers

What is the effect of NSAIDs on loop diuretics?

Decrease diuretic response Signup and view all the answers

What is the adverse effect of loop diuretics on potassium levels?

Hypokalemia Signup and view all the answers

What is the route of administration of loop diuretics?

Either oral or intravenous Signup and view all the answers

Study Notes

Drugs Modifying Salt Excretion

Proximal convoluted tubules: Carbonic anhydrase inhibitors
Thick ascending loop: Loop diuretics
Distal convoluted tubules: Thiazides
Cortical collecting duct: K-sparing diuretics

Thiazide Diuretics

Act mainly in cortical region of ascending loop of Henle and distal convoluted tubule
Decrease reabsorption of sodium by inhibiting Na+/Cl- cotransporter (NCC) on luminal membrane of tubules
Indications:
- Hypertension (initial therapy of choice if uncomplicated)
- Mild heart failure (to reduce extracellular volume)
- Nephrolithiasis (increase urinary calcium excretion)
- Nephrogenic diabetes insipidus (decrease blood volume and GFR)
Adverse effects:
- Volume depletion
- Hypokalemia
- Hypercalcemia
- Metabolic alkalosis
- Hyperuricemia
- Glucose/lipid effects

Types of Thiazide Diuretics

Chlorothiazide
Hydrochlorothiazide (most commonly used)
Thiazide-like diuretics:
- More potent and longer half-life than HCTZ
- Used once daily to treat hypertension
- Used in major clinical trials
Chlorthalidone
Metolazone:
- Very potent
- Intermediate half-life
- Typically used in combination with loops
- Causes Na+ excretion even in advanced heart failure
Indapamide:
- Lipid-soluble
- Long duration of action
- Significant anti-hypertensive effect with minimal diuretic effect

Loop Diuretics

High ceiling diuretics
Act in thick ascending limb of loop of Henle
Increase urinary Na+, K+, and Ca++ excretion
Adverse effects:
- Hypovolemia
- Hyponatremia
- Hypokalemia
- Hyperuricemia
- Metabolic alkalosis
Drug interactions:
- NSAIDs decrease diuretic response
- Digitalis increases risk of arrhythmias
Examples:
- Torsemide:
  - Higher potency
  - Oral bioavailability consistently ~80-100%
- Bumetanide:
  - Higher potency
  - Oral bioavailability consistently ~80-100%
- Ethacrynic acid:
  - Only non-sulfa loop diuretic
  - Most likely to cause deafness

K-Sparing Diuretics

Act in collecting duct and cortical collecting tubule
Prevent potassium from being pumped into the tubule, thus preventing its secretion
Adverse effects:
- Hyperkalemia
- GI symptoms (cramps, nausea, vomiting, diarrhea)
- CNS symptoms (dizziness, headache)
- Other symptoms (urinary frequency, weakness)
Examples:
- Amiloride:
  - Direct inhibitor of sodium influx in cortical collecting tubule
  - Clinical use: treatment of HF
- Spironolactone:
  - Competitively blocks aldosterone receptors and inhibits its action
  - Clinical use: hyperaldosteronism, hypertension, heart failure, liver failure
- Triamterene:
  - Direct inhibitor of sodium influx in cortical collecting tubule
  - Metabolized in liver, shorter half-life, given more frequently than amiloride

ADH Agonist and Antagonist

ADH agonist:
- Act on ascending loop and collecting duct
- Increase water reabsorption from collecting tubule
- Adverse effects:
  - Water overload
  - Hyponatremia
ADH antagonist:
- V2 receptor antagonists
- Block ADH action on collecting duct
- Adverse effects:
  - Nausea
  - Vomiting
  - Diarrhea
  - Headache
  - Light-headedness
  - Dizziness

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Description

Learn about the different types of diuretics, their mechanisms of action, and indications for use. From carbonic anhydrase inhibitors to k-sparing diuretics, this quiz covers it all.