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Pharmacology 2 > Diuretics > Flashcards

Diuretics Flashcards

1
Q

What is a diuretic

A

Any drug that accelerates the rate of urine formation

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2
Q

How does a diuretic work (general)

A

Removes Na+ by blocking Na+ ion channels so it cannot be reabsorbed, which in turn causes water to follow, which increases urine output

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3
Q

How much Na+ is reabsorbed at the loop of Henle

A

20-25%

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4
Q

How much Na+ is reabsorbed at the distal tubule

A

5-10%

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5
Q

How much Na+ is reabsorbed at the collecting duct

A

3%

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6
Q

What is the main clinical use of diuretics

A

To manage disorders involving abnormal fluid retention or treating hypertension

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7
Q

Where on the nephron is the most Na+ absorbed (as well as other ions)

A

At the proximal tubule

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8
Q

Where are organic acids and bases secreted at along the nephron

A

Proximal tubule

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9
Q

What is hyperuricemia

A

Too much uric acid in the blood

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10
Q

What acid do diuretics compete with in the bloodstream

A

Uric acid

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11
Q

What can happen with diuretics and uric acid

A

Diuretics compete with uric acid and are transferred out of the bloodstream. Because of this, the patient may end up with an abnormally high level of uric acid in the bloodstream, that would otherwise be normally excreted

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12
Q

What part of the nephron is the target portion for diuretics, specifically loop diuretics

A

Loop of Henle

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13
Q

What drugs cause hyperuricemia more often

A

Furosemide and hydrochlorothiazide

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14
Q

What happens to the osmolarity of the urine as it passes through the descending loop of Henle

A

The osmolarity increases because of the countercurrent mechanism that induces water reabsorption at this part of the nephron

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15
Q

What effect does the increase in osmolarity at the loop of henle have on Na+

A

It increases the salt concentration 3 fold

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16
Q

Where is one site along the nephron that osmotic diuretics works

A

Descending loop of Henle

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17
Q

Which portion of the nephron is impermeable to water

A

Ascending loop of Henle

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18
Q

What part of the nephron does loop diuretics work on

A

The work on the ascending loop of Henle because it blocks Na+ reabsorption at that sight. It is also the place along the nephron that is impermeable to water

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19
Q

What kind of diuretics work best at the site of the distal tubule

A

Thiazide diuretics

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20
Q

What happens at the the distal tubule

A

Mostly just Cl- is reabsorbed, also impermeable to water

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21
Q

Where on the nephron do antidiuretics work (ADH)

A

The collecting duct

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22
Q

What types of drugs work best on the proximal tubule

A

Carbonic anhydrase inhibitors

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23
Q

What types of drugs work on the descending limb and part of the proximal tubule

A

Osmotic diuretcs

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24
Q

What types of drugs work best on the ascending loop

A

Loop diuretics

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25
Q

What drugs work best on the distal tubule

A

Thiazide diuretics

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26
Q

What drugs work best on the collecting duct

A

Antiduretics or K+ sparing diuretics

27
Q

Common causes of edema

A
  1. Heart failure
  2. Hepatic ascites
  3. Nephrotic syndrome
  4. Premenstrual edema
28
Q

What happens with heart failure

A

The heart cannot sustain sufficient CO, and the kidneys sense a decrease in blood volume, so they respond by increasing Na+ reabsorption and fluid retention. However, the heart cannot keep up because the CO is so low

29
Q

What type of diuretics are commonly used to treat heart failure

A

Loop diuretics

30
Q

What happens with hepatic ascites

A

Blood flow in portal system is obstructed which increases portal pressure. This in combo with a decreased osmotic pressure in the blood causes fluid to escape from portal system into the abdomen

31
Q

What is nephrotic syndrome

A

Disease state of kidneys that causes the glomerulus to allow plasma proteins into the filtrate. This decreases blood osmolarity, resulting in edema

32
Q

Which diuretic category is commonly used to treat hypertension

33
Q

Thiazides

A

Most widely used diuretics, sulfonamide derivatives

34
Q

What is another name for thiazides

A

Ceiling diuretics because adding any more drug does not increase the response (aka urine output)

35
Q

What is the mechanism of action thiazides

A

Inhibit tubular resorption of Na+ and Cl- ions (at the distal tubule)

36
Q

What are two commonly used thiazides

A
  1. Hydrochlorothiazide (HCTZ)

2. Chlorthalidone (hygroton)

37
Q

How do thiazides act specifically on the tubule

A

Their site of action is on the luminal membrane of the tubule so they must be excreted into the lumen to be effective

38
Q

What happens if kidney function is impaired when using thiazides

A

They lose their efficacy because the diuretic cannot get into the tubule to act on its site of mechanism

39
Q

What are the results of thiazides

A
  1. H20, Na+, Cl- K+ excreted,
  2. does not affect acid-base status of blood.
  3. Aid in lowering peripheral vascular resistance and relaxing arterioles of smooth muscle
40
Q

Uses for thiazides

A
  1. Hypertension
  2. Heart failure (only if loop diuretics are not enough)
  3. Hypercalciuria
  4. Diabetes
41
Q

Why does thiazide work so well for BP regulation

A

Because it lowers the BP without having a huge diuretic effect (very little diuretic action happens at the distal tubule)

42
Q

Adverse effects of thiazides

A
  1. K+ depletion - most frequent problem
  2. Hyponatremia - may occur if too much water lost (hypovolemia) because body activates ADH which is an antidiuretic
  3. Hyperuricemia (gout)
  4. Volume depletion - hypotension if too long
  5. Hypercalcemia
  6. Hyperglycemia
43
Q

What are common loop diuretics

A
  1. Furosemide (lasix)
  2. Ethacrynic acid (edecrin)
  3. Bumetanide
44
Q

Which diuretics are the most efficient

A

Loop diuretics because 25-30% of na+ reabsorption occurs at the ascending loop

45
Q

What affect do loop diuretics have on ca2+

A

Increase ca2+ content in the urine (different than thiazides - that decrease ca in the urine)

46
Q

Uses of loop diuretics

A
  1. Drug of choice for reducing pulmonary edema or heart failure
  2. Treating hypercalcemia (because they increase Ca concentration in urine)
47
Q

Adverse effects of loop diuretics

A
  1. Ototoxicity - hearing issues
  2. Hyperuricemia - loops compete with uric acid, which increase the acid level in bloodstream
  3. Acute hypovolemia - severe reduction in blood volume that may be threatening
  4. K+ depletion
  5. Hyperglycemia
  6. Hypomagnesemia
48
Q

Where do K+ sparing diuretics act

A

On the collecting tubule

49
Q

How do K+ sparing diuretics work (MOA)

A

Inhibit Na+ reabsoprtion and K+ excretion (Na+/K+ exchange interference)

50
Q

MOA of K+ sparing diuretics

A

The diuretics competitively bind to aldosterone receptors. This blocks the resorption of Na+ and K+ secretion. Thus holding on to K+

51
Q

Uses of K+ sparing diuretics

A
  1. Diuretic - very inefficient due to collecting duct target
  2. K+ sparing (given with other diuretics, i.e. with thiazides in order to prevent hypokalemia)
  3. Hyper aldosteronism
  4. Heart failure
52
Q

Type of K+ sparing drug

A

Spironolactone and eplerenone

53
Q

Adverse effects of spironolactone

A
  1. Causes gastric upset
  2. Dizziness/headache
  3. gynecomastia
  4. Hyperkalemia
54
Q

What is a drug that is a carbonic anhydrase inhibitor

A

Acetazolamide

55
Q

What does acetazolamide do

A

Inhibits the enzyme carbonic anhydrase in the proximal tubule

56
Q

How does acetazolamide work

A

Causes a decrease in the ability to exchange Na+ for H+, which leads to mild diuretic effects. Blocks Na+ reabsorption, decreases H+ secretion at proximal tubule. inhibits bicarb reabsorption

57
Q

Uses of acetazolamide

A
  1. Glaucoma

2. Altitude sickness

58
Q

What are two types of osmotic diuretics

A
  1. Mannitol

2. Urea

59
Q

What is an adverse reaction of acetazolamide

A

Metabolic acidosis (because you are not able to excrete H+, it is being blocked).
Kidney stones
K+ depletion

60
Q

What is the main function of osmotic diuretics

A

To increase urinary output rather than Na+ excretion. Used to maintain urine flowing following trauma or an incident that increases toxic substances in the kidneys

61
Q

Volume depletion

A

Occurs when too much Na+ is lost and hence too much water follows

62
Q

Azotemia

A

Elevation in blood urea nitrogen and creatinine levels. Caused from insufficient filtering of the blood by the kidneys

63
Q

Diuretic resistance

A

Occurs when the patient cannot get rid of the fluid even with a diuretic (seen in heart failure patients)

Pharmacology 2 (8 decks)

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