Drugs acting on the kidneys 3

Question 1

How are prostaglandins formed ?

Answer 1

From the fatty acid arachidonic acid (in membrane phopholipids) by the cyclo-oxygenase enzymes (COX1 and 2)

Question 2

What are the 2 important prostaglandins to know about ?

Answer 2

PEG₂ and PEI₂

Question 3

What are prostaglandins needed for ?

Answer 3

• For there vasodilatory effect to increase renal blood flow and GFR (in angiotensin induced vasoconstriction in volume depleted states)
• Diuretic effect- increase water, Na & K excretion

Question 4

What is the action of NSAID’s ?

Answer 4

They inhibit COX

Question 5

When may NSAID’s precipitate acute renal failure (reduced GFR greatly) ?

Answer 5

In conditions where renal blood flow is dependent upon vasodilator prostaglandins (CHF, cirrhosis nephrotic syndrome)

Question 6

What is the tripply whammy combination and what does it result in ?

Answer 6

ACEI/ARB + diuretic + NSIAD detrimental to renal function, leading to Na retention, edema; diuretic and antihypertensive drug effects are blunted.

Question 7

What effect do NSAID’s tend to have on Na+ and H20 ?

Answer 7

Cause Na+ and H20 retention (not significant in normal patients)

Question 8

What is the mainstay of treatment of gout ?

Answer 8

Allopurinol - except in the initial acute attack of gout

Question 9

What are uricosuric agents ?

Answer 9

Second line/adjunct agents to allopurinol

e.g. Probenecid, Sulfinpyrazone, Benzbromarone

Question 10

What is the action of uricosuric agents ?

Answer 10

Act by blocking active transport of organic acids leading to reduced net reabsorption of urate

Question 11

When is the use of uricosuric agents contraindicated ?

Answer 11

In Renal impairment or history of renal stones.

Question 12

Why are patients instructed to increase there fluid intake to 2-3L when starting on a uricosuric agent ?

Answer 12

Crystallisation of urate in the urine can occur with the uricosuric drugs and it is important to ensure an adequate urine output

Question 13

What are SGLT2 inhibitors used to treat ?

Answer 13

Diabetes

Question 14

What are the different SGLT2 inhibitors ?

Answer 14

• Dapagliflozin
• Canagliflozin
• Empagliflozin

Think ‘flozin’

Question 15

Where does glucose reabsorption occur in the nephron ?

Answer 15

• Proximal tubule - mediated by sodium glucose co-transporters -SGLT 1 & 2
• SGLT transporters - transport glucose against a concentration gradient by coupling it to Na+ influx glucose

Question 16

Should there be glucose in the urine ?

Answer 16

No - normally 100% of glucose is reabsorbed by the SGLT transporters

Question 17

What is the mechanism of action of SGLT2 inhibitors ?

Answer 17

Inhibit reabsorption of glucose by acting on the SGLT2 transporters

Question 18

What do SGLT2 inhibitors cause ?

Answer 18

• Excretion of glucose
• Decreases in HbA1c
• Weight loss

Question 19

What is the msot common side effect of SGLT2 inhibitors ?

Answer 19

increased incidence of genital bacterial and fungal infections