2: Drugs acting on the kidney 3 Flashcards Preview

Renal Week 4 2017/18 > 2: Drugs acting on the kidney 3 > Flashcards

Flashcards in 2: Drugs acting on the kidney 3 Deck (37)
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1
Q

Which diuretic acts on the proximal tubule to inhibit water reabsorption?

A

Mannitol

Increases osmolarity of filtrate, so less water enters interstitium by osmosis

2
Q

How is mannitol administered?

A

IV

3
Q

How does mannitol enter the filtrate?

A

Filtered by glomeruli

4
Q

How does mannitol decrease

a) water
b) sodium reabsorption?

A

a) Increases omsolarity of filtrate, so less water wants to pass into the interstitium of the proximal tubules

b) Filtrate is more dilute because there’s more water, so Na+ reabsorption decreases

5
Q

What is mannitol used to treat?

A

Increased intracranial pressure (cerebral oedema, papilloedema)

Increased intraocular pressure (glaucoma)

6
Q

What are two side effects of mannitol?

A

Hyponatraemia (inc. blood volume, so diluted)

Hypervolaemia

7
Q

What complication of diabetes causes osmotic diuresis?

Why?

A

Hyperglycaemia

All the SGLT2 channels are saturated

So less Na+ reabsorbed

So less H2O reabsorbed

Osmotic diuresis

8
Q

What is an example of a carbonic anhydrase inhibitor?

A

Acetazolamide

9
Q

What is a renal effect of carbonic anhydrase inhibitors?

A

Stop carbonic anhydrase from converting H+ and HCO3- to carbonic acid

So BICARBONATE is excreted

Causing metabolic acidosis

10
Q

Which eye condition is carbonic anhydrase inhibitors used to treat?

A

Glaucoma

Inhibits secretion of aqueous humour, reducing intraocular pressure

11
Q

Where is aldosterone secreted from?

What does it do?

A

Adrenal cortex

Increases Na+ reabsorption and K+ secretion from the distal tubules and collecting ducts

12
Q

Where is ADH secreted from?

What does it do?

A

Posterior pituitary gland

Increases water reabsorption from collecting ducts

13
Q

Which receptor does ADH bind to?

A

V2 receptors

14
Q

What is the problem in

a) neurogenic
b) nephrogenic

diabetes insipidus?

A

a) Lack of ADH secretion from posterior pituitary

b) Resistance of V2 receptors to ADH

15
Q

What causes nephrogenic diabetes insipidus?

A

Resistance of V2 receptor to ADH binding

16
Q

Which gene mutates to cause nephrogenic diabetes insipidus?

A

AVPR2

17
Q

How is neurogenic diabetes insipidus treated?

A

Desmopressin

18
Q

Why does ethanol cause increased diuresis?

A

Alcohol inhibits ADH

19
Q

Why does smoking cause reduced diuresis?

A

Nicotine stimulates ADH

20
Q

What type of receptor is V2?

A

G-protein coupled receptor

activates adenyl cyclase, then cAMP etc.

21
Q

What change in the apical membrane does activation of V2 receptors cause?

A

Increased expression of aquaporins

22
Q

Which drugs block V2 receptors?

How do they affect

a) water reabsorption
b) Na+ reabsorption?

A

Vaptans

Block V2 receptors, so less water is reabsorbed

Same amount of Na+ is reabsorbed, but smaller BV, so HYPERNATRAEMIA

23
Q

What is an example of a vaptan which is used to treat SIADH and ADPKD?

A

Tolvaptan

24
Q

Which transporters are found in the proximal tubules and can be targeted by -flozins?

A

SGLT2

25
Q

Which sodium-glucose transporters are found in the

a) early proximal
b) late proximal

tubules?

A

a) SGLT2

b) SGLT1

26
Q

How does SGLT work?

A

Transports glucose INTO cells, against a concentration gradient, by coupling it to Na+ transport down a concentration gradient

27
Q

Which SGLT channels have

a) a low affinity and high capacity
b) a high affinity and low capacity?

Why is this useful?

A

a) SGLT2 (proximal)

b) SGLT1 (distal)

If SGLT2 is overloaded with glucose, SGLT1 picks up the rest

28
Q

What renal symptom do SGLT2 inhibitors cause?

A

Glycosuria

sugary urine

29
Q

Which drugs are used to inhibit SGLT2 inhibitors in the treatment of diabetes?

A

-flozins

e.g empagliflozin

30
Q

What are the effects on SGLT2 inhibitors?

A

Reduces HbA1c

Weight loss

31
Q

Given that they cause glycosuria, what is a side effect of SGLT2 inhibitors?

A

UTI

32
Q

Which acid is metabolised by enzymes to form prostaglandins?

A

Arachidonic acid

33
Q

Which enzymes metabolise arachidonic acid to form prostaglandins?

A

COX1 and COX2

34
Q

What do prostaglandins cause in the kidney?

A

1. Vasodilation of the afferent arteriole (directly)

2. Vasoconstriction of the efferent arteriole (by stimulating RENIN release)

Help to maintain vascular tone of kidneys

35
Q

What property of the kidney do prostaglandins have a large effect on?

A

GFR

36
Q

How do prostaglandins increase GFR?

A

1. Prostaglandins DILATE afferent arteriole, increasing RBF

2. Also stimulate secretion of renin, causing Angiotensin II to CONSTRICT efferent arteriole, increasing filtration pressure

37
Q

What may NSAIDs cause in patients with kidney problems?

Why?

Which other drugs may contribute to this?

A

Acute renal failure

Inhibit COX1 and COX2, inhibiting prostaglandin production

Renal vascular tone disrupted, decreased renal blood flow causes ischaemic nephropathy > AKI

ACE inhibitors, ARBs, diuretics