Urinary pharmacology

Question 1

What do diuretics do? How do they work?

Answer 1

Increase output of urine

Excrete sodium and water to prevent retention

Question 2

Diuretics can be direct or indirect. How do these diuretics work?

Answer 2

Direct - acts on cell of the nephron

Indirectly - modify filtrate content

Question 3

What is a common problem with diuretics? Why?

Answer 3

Hypokalaemia

Potassium lost with sodium

Question 4

What are the 5 groups of diuretics?

Answer 4

Osmotic diuretics
Potassium sparing diuretics
Loop diuretics
Carbonic anhydrase inhibitors 
Thiazides

Question 5

Are osmotic diuretics direct or indirect? How do they work?

Answer 5

Indirect
Alter concentration of filtrate - they are filtered through the glomerulus but not reabsorbed so alter osmotic pressure in the nephron

Question 6

What effect does an increased amount of filtrate have on sodium reabsorption?

Answer 6

Increased filtrate = less sodium reabsorption

Question 7

Give an example of an osmotic diuretic?

Answer 7

Mannitol

Question 8

How are osmotic diuretics administered?

Answer 8

IV

Question 9

What are osmotic diuretics used for?

Answer 9

Olguric renal failure (can’t urinate)
Cerebral oedema
Glaucoma
Forced diuresis if poisoned

Question 10

What is a side effect of an osmotic diuretic?

Answer 10

Initial increase in ECF

Can worsen oedema or cardiac failure

Question 11

Where is carbonic anhydrase? What is the function of carbonic anhydrase?

Answer 11

In PCT, eyes and RBCs

Dissociates carbonic acid to produce H+

Question 12

How do carbonic anhydrase inhibitors work? How is ionic balance maintained?

Answer 12

Inhibit carbonic anhydrase
Decrease H+ production and reduced Na/H+ exchange
Cl- retained to maintain ionic balance

Question 13

What affect do carbonic anhydrase inhibitors have on the pH of urine?

Answer 13

Make it alkalotic

Question 14

How are carbonic anhydrase inhibitors administered?

Answer 14

Orally

Question 15

What are carbonic anhydrase inhibitors used to treat?

Answer 15

Oedema

Not used directly as a diuretic but have that effect

Question 16

What are the adverse effects of carbonic anhydrase inhibitors?

Answer 16

Metabolic alkalosis

PUPD

Question 17

When can’t carbonic anhydrase inhibitors be used and why?

Answer 17

Liver disease

Alkaline urine means NH4 produced in kidneys goes into circulation

Question 18

Which diuretics are the most powerful?

Answer 18

Loop diuretics

Question 19

How do loop diuretics work?

Answer 19

Inhibit Na/K/Cl ransport in the LOH
Increase delivery of Na to DCT
Increase excretion of K, H+, Mg and Ca2+

Question 20

How are loop diuretics administered?

Answer 20

Orally

Parenterally

Question 21

What are loop diuretics used to treat?

Answer 21

Oedema

Congestive heart failure

Question 22

What are the adverse effects of loop diuretics?

Answer 22

Dehydration
Hypovolaemia if no water access
Hypokaelmia
ECF disturbances

Question 23

Thiazides are less powerful diuretics. Why are they still used?

Answer 23

Less side effects
Oedema
Dissolution of calcium containing bladder/kidney stones

Question 24

How do thiazides work?

Answer 24

Inhibit Na/Cl co-transport before aldosterone stimulated Na/K exchange
Increase Na, Cl, Mg and K excretion
Decrease calcium excretion

Question 25

Are loop diuretics more powerful diuretics than thiazides? Why?

Answer 25

Loop diuretics more powerful | Majority of Na has been reabsorbed in thiazides

Question 26

What are the adverse effects of thiazides?

Answer 26

``` Hypokalaemia Dehydration Hypovolaemia if no water access ECF disturbances (less severe than loop diuretics) Hyperglycaemia ```

Question 27

How are thiazides administered?

Answer 27

Orally

Question 28

Are potassium sparing diuretics powerful? When are they used?

Answer 28

Not when used alone | Used with loop diuretics and thiazides to prevent hypokalaemia

Question 29

How do potassium sparing diuretics work?

Answer 29

Affect Na but not K | 2 ways: competitive inhibitors of aldosterone or inhibitors of Na reabsorption (therefore more Na/K/ATPase activity)

Question 30

What are the adverse effects of potassium sparing diuretics?

Answer 30

Hyperkalaemia

Question 31

When should potassium sparing diuretics not be used?

Answer 31

Renal impairment Diabetes Metabolic acidosis Don't use more than one together!

Question 32

What are potassium sparing diuretics used for?

Answer 32

Oedema | Preventing hypokalaemia

Question 33

Why can different diuretics be used together?

Answer 33

Sequential nephron blockade - act at different points in the nephron

Question 34

How are potassium sparing diuretics administered?

Answer 34

Orally