Diuretics

Question 1

Give some drugs that decrease kidney function

Answer 1

ACEi
Aminoglycosides
NSAIDS
Penicillin
Cyclosporin
Metformin

Question 2

What happens in renal artery stenosis?

Answer 2

Decreased blood flow to kidneys causes a decrease in the GFR. Decreased GFR stimulates efferent arteriole constriction to increase GFR as a result of activation of the RAAS.

Question 3

What happens when you give an ACEi in renal artery stenosis?

Answer 3

Prevents vasoconstriction of efferent arteriole by angiotensin II, therefore causing a reduction in the GFR which causes renal failure.

Question 4

What changes in prescribing do you need to make in someone with renal disease?

Answer 4

Avoid nephrotoxinsReduced dose in line with the GFRMeasure plasma drug levels and renal function when the drug has a narrow therapeutic window

Question 5

What are some characteristics of patients who have renal disease?

Answer 5

Are more likely to develop hyperkalaemiaUraemic patients are more likely to bleed

Question 6

What are the functions of the kidney?

Answer 6

Regulatory- fluid, acid-base and electrolyte balanceExcretory- waste products, drug eliminationEndocrine- RAAS, erythropoeitin, prostaglandinsMetabolism- vit D, polypeptides (insulin and PTH)

Question 7

Give the drugs that act on the renal tubules

Answer 7

Carbonic Anhydrase InhibitorsOsmotic DiureticsLoop DiureticsThiazide DiureticsPotassium Sparing DiureticsAldosterone AntagonistsADH Antagonists

Question 8

What are the main reasons why you would use diuretics?

Answer 8

Heart failureHypertensionDecompensated liver failure

Question 9

Diuretics used in heart failure

Answer 9

Loop diureticsThiazides

Question 10

Diuretics used in hypertension

Answer 10

Aldosterone antagonistsThiazide

Question 11

Diuretics used in decompensated liver failure

Answer 11

SpironolactoneLoop

Question 12

What are the main issues you need to take into account when prescribing in renal disease?

Answer 12

Drugs can reduce kidney function by direct of indirect toxicity If reduced kidney function, can get drug accumulating to toxic levels, even at normal doses.

Question 13

What are the emergency treatments for hyperkalaemia?

Answer 13

Calcium gluconate - reduces effect of K+ on the heartIV insulin and glucose- shifts K+ into ICFDialysis

Question 14

What are some longer term treatments for hyperkalaemia?

Answer 14

Remove excess K+- dialysis- oral K+ binding resins (bind K+ in gut)Reduce intakeTreat cause

Question 15

What are the ECG changes you will see with hyperkalaemia?

Answer 15

Tall, peaked T wavesProlonged PR intervalST depressionWidened QRS intervalVentricular fibrillation