Diuretics

Question 1

nephron

Answer 1

functional unit of kindey

Question 2

four regions of nephron

Answer 2

1) glomerulus

2) proximal convoluted tubule

3)loop of Henle

4) distal convoluted tubule

Question 3

where does nephron fluid flow into

Answer 3

collecting ducts

Question 4

upper portion of nephron is in

Answer 4

renal cortex

Question 5

lower portion of nephron is located in

Answer 5

renal medulla

Question 6

why are the nephron located different parts of the kidney (upper and lower)

Answer 6

allows different urine concentrations

Question 7

kidneys main functions

Answer 7

1) cleansing ECF and maintenance of ECF volume and composition

2) maintenance of acid-base balance

3) excretion of metabolic waste and foreign substances (toxins, drugs, etc.)

Question 8

filtration

Answer 8

small molecules in plasma undergo filtration
- large particles excluded

Question 9

reabsorption

Answer 9

movement of fluids and molecules from nephron to peritubular capillaries

Question 10

how do diuretics primarily work?>

Answer 10

interfering with reabsorption

Question 11

active secretion (requires energy)

Answer 11

movement of fluids and molecules from peritubular capillaries back to nephron

Question 12

what are the kidneys 2 pumps for active secretion?

Answer 12

1) transports organic acids

2) transports organic bases

Question 13

Pathway of renal fluid through nephron

Answer 13

proximal convoluted tubule

loop of Henle

early distal convoluted tubule

distal convoluted tubule

Question 14

percentages of sodium/chloride reabsorbed at specific sites

Answer 14

proximal convoluted tubule- 65%
- by the end of proximal tubule, Na/Cl only solutes that remain

ascending limb of Henle loop
20%
-not permeable to water
= osmolarity returns to orig. filtrate of 300mOsm/L

Early distal convoluted tubule
10%
-water follows passively

distal convoluted tubule and collecting tubule
1% - 5%

Question 15

What important processes happen at late distal and collecting ducts?

Answer 15

1) exchange of sodium for potassium
- under influence of aldosterone

2) Determines final concentration of urine
- regulated by antidiuretic hormone

Question 16

What does aldosterone stimulate?

Answer 16

stimulates linked process of sodium reabsorption and secretion of potassium

Question 17

Basic mechanism of how diuretics work

Answer 17

Blockage of Sodium/ Chloride reabsorption
- creates increased osmotic pressure within nephron –> prevents passive reabsorption of water

• diuretics cause both sodium/chloride and water to be retained in nephron
  –> excretion of both in urine
• increase in urine flow directly related to AMOUNT of na/cl BLOCKED

Question 18

where do drugs blocking na/cl in the nephron have the most profound diuresis

Answer 18

earliest in nephron (proximal, loop)

Question 19

how much will diuretics increase urine output by?

Answer 19

1.8L for every 1 % blocked

Question 20

blocking a small amount of solute effect has a

Answer 20

profound effect on fluid and electrolyte composition in the body

Question 21

diuretics adverse impact on ECF

Answer 21

• hypovolemia
  -acid/base imbalance
  -altered electrolyte levels

Question 22

how can effects be minimized while using diuretics

Answer 22

-use short acting diuretics
–> allow kidneys to function in a drug free manner between periods of diuresis

Question 23

Four classifications of diuretics include

Answer 23

1) Loop diuretics (furosemide)
2) Thiazide diuretics (hydrochlorothiazide)
3) Osmotic diuretics (mannitol)
4) Potassium-sparing diuretics (aldosterone antagonists and agonists)

Question 24

Loop Diuretics

Answer 24

Most effective

site of action: loop of Henle

Question 25

Loop Diuretic drug

Answer 25

Furosemide (fur-oh-semide)

Question 26

Furosemide mechanism

Answer 26

-Bind reversible to a carrier protein that stops it from reabsorbing NA/CL - potentially 20% of na/cl reabsorption can be blocked here

Question 27

Pharmakinetics of Furosemide

Answer 27

PO- diuresis within 60 min, lasts for 8 hrs - use when rapid onset diuresis NOT REQUIRED IV- within 5 min -critical situations (pulmonary edema) metabolism: hepatic excretion: renal

Question 28

Adverse effects of Loop Diuretics

Answer 28

Hyponatremia, dehydration - dry mouth, unuasual thirst, low urine output - initiate therapy with low doses and monitor weight loss Hypotension - (1) from loss of water - (2) relaxation of venous smooth muscle - reduced venous return to heart --> monitor BP Hypokalemia: low levels of Na -if serum levels fall below 3.5 mEq/L fatal dysrhythmias may occur - CONSUME K rich foods Ototoxicity - hearing impairment/ severity depends on different loop diuretics

Question 29

Loop Diuretic drug interactions

Answer 29

Dioxin: drug used for heart failure/ cardiac dysrhythmias - loop diuretics cause hypokalemia --> increases risk of ventricular dysthymias Ototoxic: combined with furosemide should be avoided

Question 30

therapeutic uses of loop diuretics

Answer 30

hypertension pulmonary edema cardiac edema

Question 31

major difference between max diuresis with thiazides and loop diuretics is that

Answer 31

maximal diuresis is lower with thiazides

Question 32

Thiazide drug name

Answer 32

Hydrochlorothiazide (hydro-chlora-thi-a-zide)

Question 33

Mechanism of Thiazides

Answer 33

Blocks Na?Cl reabsorption in early segment of distal tubule - only 10% reabsorbed her = change in urine flow is lower

Question 34

therapeutic uses of thiazides

Answer 34

FIRST choice for ESSENTIAL hypertensin - can often by treated with thiazides alone FIRST choice for EDEMA treatment associated with mild to moderate heart failure

Question 35

What responses do Potassium-Sparing Diuretics Ellicit

Answer 35

(1) MODEST increase in urine production (2) Substantial Decrease in Potassium excretion - usually used in combination to counteract K loss

Question 36

Drug name for Potassium-Sparing Diuretics

Answer 36

Spironolactone (spira-no-lack-tone)

Question 37

Mechanism of Potassium- Sparring Diuretics

Answer 37

Blocks action of aldosterone in distal convoluted tubule and collecting duct Aldosterone acts to increase na/cl reabsorption and increase secretion/excretion of K+ Inhibition of Aldosterone = increased reabsorption of potassium back into interstitial fluid

Question 38

Potassium- Sparring diuretics adverse effects

Answer 38

Hyperkalemia - fatal dysrhythmias Endocrine effects - spironolactone is a steroid derivative --> menstrual irregularities, impotence, deepening of voice ---> BLOCKS TESTOSTERONE/ ESTROGEN effects

Question 39

Therapeutic uses of potassium-sparring diuretics

Answer 39

hypertension and edema - used with combination with other diuretics COUNTERACT POTASSIUM-WASTING EFFECTS of other diuretics HEART FAILURE- reduces mortality in sever heart failure patients

Question 40

Potassium- Sparring Diuretics drug interactions

Answer 40

don't combine with ingestion of potassium supplements and other products high in potassium

Question 41

Mannitol

Answer 41

osmotic diuretic

Question 42

mechanism of action of mannitol

Answer 42

after IV admin. mannitol is filtered by glomerulus into nephron - undergoes minimal reabsorption -creates an increased osmotic pressure in nephron RESULTS - inhibits passive reabsorption of water Degree of diuresis directly related to mannitol in tubular filtrate

Question 43

Pharmacokinetics of mannitol

Answer 43

IV- diuresis begins in 30-60 min lasts 6-8 hours excreted intact in urine

Question 44

Therapeutic uses of mannitol (2)

Answer 44

Prophylaxis of Renal failure - if blood flow to kidney is decreased= great reduction in filtrate volume - low filtrate volume = most na/cl reabsorbed (water follows) - urine production ceases - kidney failure occurs - mannitol reduces risk because it is not reabsorbed in nephron --> preserves urine flow Reduction of Intracranial pressure (ICP) - mannitol's presence in brain blood vessels (cannot pass through BBB) - creates osmotic force that draws fluid from brain into blood = reduction ICP