Diuretics Facts

Question 1

three major applications of diuretics

Answer 1

treatment of hypertension
mobilization of edamatous fluid associated with heart failure, cirrhosis, or kidney disease
prevent renal failure

Question 2

three main functions of the kidney

Answer 2

maintain ECF volume and composition
maintain acid-base balance
excrete waste products and toxic substances

Question 3

diuretics work primarily with interfering with

Answer 3

reabsorption

Question 4

_____% of filtered sodium and chloride are reabsorbed in the proximal convoluted tubule

Answer 4

65%

Question 5

how much bicarbonate and potassium in filtrate is reabsorbed in the proximal convoluted tubule

Answer 5

essentially all

Question 6

solutes and water are reabsorbed to an equal extent, making the tubular urine ______

Answer 6

remain isotonic

Question 7

urine becomes concentrated in the

Answer 7

descending Henle loop (from 300 to 1200 mOsm/L

Question 8

in the ascending loop of Henle, _____% of filtered sodium and chloride is reabsorbed

Answer 8

20%

Question 9

the tonicity of the urine returns back to that of the original filtrate in the

Answer 9

ascending Henle loop (300mOsm/L) (not permeable to water)

Question 10

in the distal convoluted tubule _____% of filtered sodium and chloride is reabsorbed

Answer 10

10%

Question 11

mechanism of action of most diuretics

Answer 11

blockade sodium and chloride reabsorption

Question 12

how diuretics work

Answer 12

by blocking reabsorption of Na and Cl, it creates osmotic pressure within the nephron that prevents the passive reabsorption of water. since they remain in the nephron, it promotes excretion of both

Question 13

common side effects of diuretics

Answer 13

hypovolemia
electrolyte imbalance
acid-base imbalance

Question 14

the most effective diuretics available are

Answer 14

loop diuretics (Henle loop)

Question 15

the most common loop diuretic used is

Answer 15

furosemide (Lasix)

Question 16

how does furosemide function

Answer 16

blocks sodium and chloride reabsorption in the ascending loop, passively preventing reabsorption of water. because of the large amount of Na and Cl blocked (20%) it can cause profound diuresis

Question 17

pharmacology of loop diuretics

Answer 17

acts quickly (60 mins orally, 5 mins IV)
lasts 5 hrs PO, 2 hrs IV

Question 18

conditions that justify loop diuretics are

Answer 18

pulmonary edema from CHF
edema that has been unresponsive to less efficacious diuretics
hypertension that can’t be controlled with other diuretics
especially useful because can promote diuresis even with low GFR and RBF

Question 19

adverse reactions of loop diuretics

Answer 19

dehydration
hypotension
hypokalemia (dysrhythmias)
ototoxicity (hearing impairment)

Question 20

drug interactions of loop diuretics

Answer 20

digoxin (for heart failure and dysrhythmias) (hypokalemia cause problems)
ototoxic drugs
potassium-sparing diuretics (counter hypokalemia)
NSAIDs (decrease effect of diuretics)

Question 21

different loop diuretics

Answer 21

furosemide (Lasix)
ethacrynic acid (Edecrin)
bumetanide (Bumex)

Question 22

mechanism of action of thiazide diuretics

Answer 22

block reabsorption of Na and Cl in early segment of distal convoluted tubule
only 10% filtered NaCl is normally reabsorbed here so urine flow these drugs cause is much lower than loop diuretics
ineffective when GFR is low

Question 23

pharmacology of thiazide

Answer 23

diuresis begins 2 hours after orally taken
peak within 4-6 hours
may last 12 hours

Question 24

thiazide mainly used for

Answer 24

HTN
edema from mild to moderate heart failure
edema from hepatic or renal disease

Question 25

adverse effects of thiazide

Answer 25

same as loop diuretics except not ototoxic
dehydration
hypotension
hypokalemia (dysrhythmias)

Question 26

types of thiazide drugs

Answer 26

8 types and all end in thiazide
most common hydrochlorothiazide
all by mouth

Question 27

spironolactone (Aldactone) (aldosterone antagonist) mechanism of action

Answer 27

blocks action of aldosterone in distal tubule
aldosterone increase sodium absorption and increase potassium excretion so it does the opposite
minimal diuresis
action delayed (up to 48 hours)

Question 28

uses of spironolactone

Answer 28

HTN and edema
often used with loops or thiazides to prevent hypokalemia
block effects of aldosterone in patients with hyperaldosteronism

Question 29

adverse effects of spironolactone

Answer 29

hyperkalemia
endocrine effects
*menstrual irregularity
*impotence
*deepening of voice
*gynecomastia

Question 30

drug interactions - spironolactone

Answer 30

use with caution with drugs that elevate potassium and block aldosterone (ACEI, angiotensin receptor inhibitors, renin inhibitors, K+ sparing diuretics)

Question 31

osmotic diuretics used

Answer 31

mannitol (Osmitrol)
there are others used, but only mannitol used for diuretic action

Question 32

mechanism of action of osmotic diuretics

Answer 32

very different from other diuretics
*simple sugar that creates osmotic force in glomerulus
*freely filtered at the glomerulus
*little reabsorption
*not metabolized
*pharmacologically inert (no direct effects on biochemistry or physiology of cells)
*increases osmotic pressure of filtrate, water not reabsorbed and therefore excreted
*amount of diuresis directly related to amount of drug present
*little effect on secretion of electrolytes
*effective in reducing intracranial edema and therefore intracranial pressure (ICP)

Question 33

pharmacology of osmotic diuretics

Answer 33

does not cross GI endothelium
given only IV - diuresis begins after 30-60 min and lasts 6-8 hours

Question 34

uses of osmotic diuretics

Answer 34

prevent renal failure - drawing water into the nephron
reduce intracranial pressure (ICP) - presence in brain blood vessels creates osmotic force which pulls fluid from brain into blood
reduce intraocular pressure - creates osmotic force that pulls fluid into the blood

Question 35

adverse reactions of osmotic diuretic

Answer 35

edema - when it exits capillaries, it draws water along