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Phar 503 > Medicinal Chemistry and Pharmacology of Diuretics > Flashcards

Medicinal Chemistry and Pharmacology of Diuretics Flashcards

1
Q

What are the functions of the kidneys

A

maintain homeostatic balance of electrolytes and water, excrete water-soluble end products of metabolism

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2
Q

What is the functional unit of the kidney

A

Nephron

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3
Q

What are the two important physical processes in urine formation

A

osmosis and active transport

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4
Q

What are the five parts of the Nephron

A

Glomerulus, Proximal Tubule, Loop of Henle, Distal Tubule, Collecting Duct

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5
Q

Filtrated plasma provided by glomerular capillary network into the Bowman’s capsule becomes what, what is a key difference

A

Luminal fluid, change in osmotic concentration

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6
Q

What are the most important molecules reabsorbed in the proximal tubule, what is the other important molecule absorbed

A

sodium chloride and bicarbonate, water

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7
Q

What enzyme is responsible for transcellular reabsorbption of sodium and bicarbonate

A

Carbonic anhydrase

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8
Q

How does carbonic anhydrase work

A

Water binds to the enzyme and grabs carbon dioxide to become carbonic acid, carbonic acid is unstable and dissociates to protons and bicarbonate, the protons and sodium are exchanged through an antiporter system to keep electrostatic equilibrium, bicarbonate and sodium are put into the interstitial fluid through a symporter system

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9
Q

What enzyme is the driving force to create an osmotic gradient, what is the result

A

Na+/K+ ATPase, creates Na+ deficit in luminal cell and draws sodium from luminal fluid

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10
Q

How are other ways sodium enters the cell or anti-luminal membrane

A

transcellular transport (passive to luminal membrane, active to anti-luminal membrane), paracellular transport (diffusion)

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11
Q

What part of the nephron is most responsible for absorbing Sodium, how much sodium does it reabsorb

A

proximal tubule, 60%

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12
Q

What are the two portions of the loop of Henle

A

Descending limb, ascending limb

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13
Q

Which part of the Loop of Henle water permeable, is it active or passive

A

Descending limb, osmosis (passive)

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14
Q

Which part of the Loop of Henle is water impermeable, what is usually reabsorbed at what ratio

A

Ascending limb, NaCL (1:2)

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15
Q

What percentage of the reabsorbed sodium is reabsorbed by the loop of Henle, which part

A

30%, Ascending Limb

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16
Q

How does sodium and chloride get into the cell in the ascending limb

A

symporter system

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17
Q

What part of the nephron is hormone driven, what hormones drive it

A

Distal Tubule,ADH and Renin

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18
Q

Where is potassium is more likely to enter the urine

A

Collecting duct

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19
Q

How does the nephron react to hypovolemia/ dehydration

A

decreased renal blood flow and GFR, increased renin secretion, increased secretion of ADH, increased water re-absorption

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20
Q

How do diuretic agents work

A

promote urination by increasing the rate of renal excretion of water and electrolytes

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21
Q

T/F: Most diuretics work by inhibitng Na+ transport at one or more of the four mayjor anatomical sites

A

True

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22
Q

What will influence how much diuretic enters the luminal fluid by the filtration process

A

GFR. plasma concentration of diuretic agent, fraction of the drug that is bound to unfiltrable plasma proteins

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23
Q

How do the diuretics get to their site of action

A

travel through the blood stream and bind to OATs (acids) or OCTs (bases) where they are secreted

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24
Q

What is the driving force of the glomerular filtration process

A

hydraulic pressure (pumping heart)

25
Q

What is the role of the Na+/K+ ATPase in the anti-luminal membrane

A

driving force of sodium re-absorption and creates a sodium deficit in the luminal cell

26
Q

T/F: Water is reabsorbed throughout the entire Loop of Henle

A

False- the ascending Loop of Henle is not water-permeable

27
Q

Where is the salt (osmotic) concentration is higher

A

Medulla

28
Q

What are the classes of diuretics

A

osmotics, carbonic anhydrase inhibitors, thiazides, loop, potassium sparing

29
Q

What are properties of osmotic dieuretics

A

highly water soluble, with minimal re-absorption by the renal tubule that are freely filtered through the Bowman’s capsule into the renal tubules

30
Q

What are the osmotic diurectics

A

Mannitol, isosorbide, and sorbitol

31
Q

What is MOA of osmotic diuretics

A

artificially concentrate the urine causing less sodium absorption and water reabsorption

32
Q

Where do the osmotics usually work at

A

Proximal tubule and descending limb

33
Q

Where do carbonic anhydrase inhibitors do most of the action at

A

Proximal tubule

34
Q

What is the MOA of carbonic anhydrase

A

inhibiton of renal carbonic anhydrase decreases sodium carbonate reabsorption leading to increased volume of luminal fluid

35
Q

What do all carbonic anhydrase drugs have in common

A

Sulfanilamide lead compound (unsubstituted sulfamoyl group and aromatic system)

36
Q

T/F: Carbonic anhydrase are competitive inhibitors that block the binding of water and carbon dioxide

A

True

37
Q

What are carbonic anhydrase usually used for

A

Glaucoma

38
Q

Where do thiazide diuretics work

A

Distal tubule

39
Q

T/F: Thiazide have a strictly diuretic activity

A

False: Thiazide diuretics posses a diuretic activity along with CA inhibitory activity due to its sulanilamide moeiry

40
Q

What occurs in the distal tubule, how do thiazides change this

A

Symporter system that carries sodium and chloride in the luminal cells, inhibit the sodium and chloride symporter leading to an increase in water excretion

41
Q

What is basic in thiazide structure in order for them to work

A

Six membered aromatic phenyl ring attached to a cyclic six membered ring, a free sulfonilmide and one in the cyclic ring

42
Q

What is essential for diuretic activity in thiazides

A

an electron withdrawing group at C-6, free sulfonamide at C-7

43
Q

T/F: Substituation with a lipophilic group at C-3 increases diuretic potency and/or its duration of action

A

True

44
Q

What is the most apparent adverse effect of using thiazide diuretics, why

A

Hypokalemia, Due to high Sodium in lumen due to thiazide there is increased K+ secretion in the collecting duct when sodium is reabsorbed

45
Q

What is another electrolyte disorder caused by thiazide diuretics, why

A

hypercalcemia, long-term thiazide treatment is known to trigger an increase in proximal tubule reabsorption of fluid, uric acid, and electrolytes (such as calcium)

46
Q

How do thiazides lead to hyperuricemia

A

Both thiazides and uric acid are weak organic acids that compete for OATs

47
Q

Which diuretics are used in emergencies, where do they work

A

Loop diuretics, thick ascending loop

48
Q

What is the most potent Loop diuretic, which is mostly prescribed to patients, which lacks the CA inhibitor activity due to lacking the sulfamoyl group

A

Bumetanide, Furosemide, Torsemide

49
Q

Which Loop diuretics not only inhibit the luminal Na+/K+/2Cl- symporter system but also the Na+/K+ATPase, what do they lack from other Loop diuretics

A

Etacrynic acid and Indacrinone, Lack CA inhibition due to no sulfamoyl group

50
Q

What is MOA of potassium sparing diuretics

A

competitive inhibition of aldosterone receptor or blockade of sodium channels at the luminal membrane

51
Q

What are potassium sparing diuretics that selectively block sodium channels, where do they work, what is their ionic state

A

Amiloride and Triamterene, collecting duct, positive (basic)

52
Q

What is aldosterone, what does it do

A

endogenous mineralocoricoid with antidiuretic hormone action through binding mineralocorticoid receptor leading to more Na+/K+ATPase and more Na+ channels

53
Q

What are potassium sparine diuretics that are aldosterone receptor antagonists,

A

spironolactone, canrenone, and eplerenone

54
Q

Which aldosterone receptor antagonists is a active metabolite of spironolactone, which is more selective for the aldosterone receptor

A

canrenone and eplerenone

55
Q

T/F: Both potassium sparing diuretics bind to Na channels directly leading to potassium sparing

A

False: Amiloride and triamterene block these channels directly while spironolactone, canrenone, eplerenone are used to reduce the concentration of these channels

56
Q

What is the mutual effect of all diuretics

A

increase in osmotic concentration of the luminal fluid and resulting in reduced water re-absorption

57
Q

How do diuretics increase the risk of gout

A

Uric acid is built up in the body and crystallizes, this happens because Uric acid must now competes with diuretics that also use the enzyme OATs in order to get to the urine

58
Q

Which class diuretics work on the proximal tubule and descending loop of henle, which work on just the proximal tubule, which work on the ascending loop of henle, which work on the distal tubule

A

osmotic, carbonic anhydrase, Loop, thiazides and potassium sparing

Phar 503 (25 decks)

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