3 - Diuretics

Question 1

Which drugs are thiazide diuretics?

Answer 1

• Hydrochlorothiazide
• Chlorthalidone
• Metolazone

Question 2

Which drug are loop diuretics?

Answer 2

• Furosemide

- Ethacynic acid

Question 3

Which drug is a potassium sparing diuretic?

Answer 3

Spironolactone

Question 4

What is the aim of therapy w/ diuretics?

Answer 4

Decrease sodium reabsorption by a few %

Question 5

What would happen if Na reabsorption drops to 95%?

Answer 5

1250 mmol/day of Na is excreted, so 9 litres of extracellular fluid is lost

Question 6

What are the functions of the proximal tubule and which drug works against each function?

Answer 6

• Reabsorbs filtrate water and electrolytes (mannitol, unreabsorbed glucose)
• 100% of glucose reabsorbed (dapaglifozin)
• 85% of bicarbonate reabsorbed (acetazolamide)

Question 7

What is the function of the ascending loop of Henle and which drug works against this function?

Answer 7

• Na, K, Cl co-transported and Ca and Mg follow (reabsorbed)

- Furosemide

Question 8

What is the function of the distal tubule and which drug works against this function?

Answer 8

• Na/Cl reabsorbed, calcium excreted

- Metolazone

Question 9

Is water reabsorbed in the ascending loop of Henle?

Answer 9

No

Question 10

Is water reabsorbed in the distal tubule?

Answer 10

No

Question 11

What are the function of the collecting ducts and which drugs work against these functions?

Answer 11

• Aldosterone increase Na reabsorption and increases K and H excretion (spironolactone)
• ADH (vasopressin) increases water permeability and reabsorption (conivaptan)

Question 12

Where do thiazide diuretics work?

Answer 12

• Distal tubule to increase NaCl excretion and decrease Ca excretion
• Some proximal tubule affect (only important when combined w/ loop diuretics)

Question 13

What are the uses of thiazide diuretics?

Answer 13

• Edema (heart failure, liver cirrhosis)

- Hypertension

Question 14

What are some disadvantages to thiazide diuretics?

Answer 14

• Increases incidence of other risk factors for CV disease (hyperglycemia, increase LDL levels)
• Increases incidence of erectile dysfunction
• Plasma volume contraction due to increased volume loss

Question 15

What are advantages to thiazide diuretics?

Answer 15

• Orally active
• Low toxicity
• No postural hypotension

Question 16

How are loop diuretics administered?

Answer 16

Orally and IV

Question 17

What are the functions of loop diuretics?

Answer 17

• Increase prostaglandin production in nephron
• Increases Na, Cl, and K excretion and Mg, Ca follow (excreted)
• Inhibits renal diluting ability and abolishes renal concentrating ability (urine becomes isotonic and slightly dilute)

Question 18

____ may decrease function of loop and thiazide diuretics

Answer 18

NSAIDs

Question 19

What are some problems w/ loop diuretics?

Answer 19

• Deafness

- Chronic dilutional hyponatremia

Question 20

What should loop diuretics never be combined w/?

Answer 20

Aminoglycoside antibiotics

Question 21

What are loop diuretics used for?

Answer 21

• Renal insufficiency
• Edema (pulmonary)
• Hypertension (not as sole medication)
• Hypercalcemia
• Heart failure

Question 22

What should be done if px not responding to a loop diuretic?

Answer 22

• Caution regarding circulating chloride concentration

- Add thiazide diuretic

Question 23

Thiazide and/or loop diuretics can cause _____ depletion

Answer 23

Potassium

Question 24

When is potassium depletion a concern w/ thiazide and loop diuretics?

Answer 24

If low potassium is already a problem (ex: heart failure, cirrhosis)

Question 25

What are the 2 main causes of potassium depletion from thiazide and loop diuretics?

Answer 25

1) Secondary hyperaldosteronism (increased renin = increased A2 = increased aldosterone => Na reabsorption and K loss) 2) Increased distal delivery (Na reabsorption inhibited in loop and distal tubule, so collecting tubules increase Na reabsorption)

Question 26

What is the tx for potassium depletion?

Answer 26

1) Dietary intake (apricots, bananas) 2) Potassium chloride tablets 3) Emergencies = IV KCl 4) Potassium sparing diuretics (given w/ other diuretics to decrease K loss)

Question 27

Rank the 3 types of diuretics from strongest to weakest at removing sodium

Answer 27

Loop > thiazide > potassium sparing

Question 28

What are the functions of spironolactone?

Answer 28

- Blocks aldosterone receptor | - Prevents cardiac remodelling, so may delay progression of heart failure

Question 29

What is the function of triamterene?

Answer 29

Decreases sodium permeability

Question 30

What effect do beta antagonists, ACE inhibitors, and ARBs have on plasma potassium concentrations?

Answer 30

May increase concentrations

Question 31

What can cause extracellular volume depletion? What are ways to overcome these?

Answer 31

- Inability to concentrate urine/save water - drink more water to excrete solutes - Inability to dilute urine/excrete excess urine - ingest hypotonic solution to excrete isotonic urine

Question 32

What effect does furosemide have on extracellular volume depletion?

Answer 32

Makes the kidney unable to concentrate or dilute urine

Question 33

What effect do diuretics have on calcium?

Answer 33

- Thiazides decrease calcium excretion (good for hypocalciuria) - Furosemide increases calcium excretion

Question 34

What effect do diuretics have on uric acid excretion?

Answer 34

Initially increased, but decreased w/ chronic administration

Question 35

What do diuretics have on lithium?

Answer 35

Increased proximal tubular reabsorption

Question 36

Which type of diuretic is preferred for tissue edema?

Answer 36

Loop diuretic

Question 37

What is the first line single therapy for hypertension?

Answer 37

Thiazide diuretic

Question 38

Why are diuretics used for heart failure?

Answer 38

Fluid retention increases vascular volume, and diuretics decrease vascular volume