Renal Pharmacology

Question 1

Describe the functions of the kidney. (12)

Answer 1

Regulatory - fluid balance, acid base balance, electrolyte balance
Excretory - waste product and drug elimination.
Endocrine - Renin, erythropoietin, prostaglandins.
Metabolism - vitamin D, insulin, morphine.

Question 2

Describe carbonic anhydrase inhibitors. (4)
Uses
MoA
Adverse drug reactions

Answer 2

Used primarily in glaucoma and altitude sickness.
Keeps HCO3- in the filtrate.
Can cause acidosis.

Question 3

Describe osmotic diuretics. (4)
MoA
Uses
Adverse drug reactions.

Answer 3

Sits in the filtrate to draw water into the filtrate.
Used in realised intracranial pressure
Can cause hypernatraemia due to excessive water loss.

Question 4

Describe loop diuretics. (7)
MoA
Uses
Adverse drug reactions.

Answer 4

Blocks NKCC2 so extra loss of Na+ and H2O.
Used to treat oedema
Can cause hypokalaemia, alkalosis, and hypocalcaemia, ototoxicity, increased LDL, gout.

Question 5

Describe thiazide diuretics. (8)
MoA
Uses
Adverse drug reaction

Answer 5

Blocks NaCl channels in the DCT causing increased Na+ and H2O delivery to the collecting duct.
Used to treat hypertension because vasodilator as well as diuresis.
Can cause hypokalaemia, alkalosis, and hypercalcaemia, gout, hyperglycaemia, increased LDL.

Question 6

Describe aldosterone antagonists. (9)
MoA
Uses
Adverse drugs reactions.

Answer 6

Spironolactone inhibits the binding of aldosterone to the intracellular receptor, so Na+/K+ expression is not upregulated.
Used in heart failure, hypertension, and hyperadrenalism.
Hyperkalaemia, impotence, painful gynaecomastia.

Question 7

Describe K+ sparing diuretics. (3)
MoA
Uses.

Answer 7

Direct inhibition of ENaC to keep Na+ in the filtrate.

Used only when there is hypokalaemia.

Question 8

Describe two non-pharmacological diuretics. (5)

MoA

Answer 8

Alcohol - inhibits ADH release

Caffeine - increased GFR and decreased Na+ resorption.

Question 9

Describe two ADH antagonists. (6)
MoA
Uses

Answer 9

Lithium - diuretic but not natriuretic. Inhibits ADH action. Used to treat bipolar disorder.
Tolvaptan - diuretic but not natriuretic. ADH antagonist. Used to treat hyponatramia.

Question 10

Describe generic adverse drug reactions of drugs that act on the kidney. (8)

Answer 10

Hypovolaemia and hypotension - RAAS activation - AKI
Electrolyte disturbance - Na+, K+, Ca2+, Mg2+
Metabolic abnormalities - depends on drug - glucose levels esp
Anaphylaxis / photosensitivity rash etc - rare.

Question 11

Describe the drug interactions with K+ sparing diuretics. (3)

Answer 11

ACEi - hyperkalaemia - arrhythmias.

Question 12

Describe the drug interactions with loop diuretics. (10)

Answer 12

Aminoglycosides (eg gentamicin) - nephro- and ototoxicity.
Digoxin - hypokalaemia - increased digoxin binding - digoxin toxicity.
Steroids - increased hyperkalaemia risk
Lithium - reduced lithium levels

Question 13

Describe the drug interactions with thiazide diuretics. (14)

Answer 13

Digoxin - hypokalaemia - increased digoxin binding - digoxin toxicity.
Beta blockers - hyperglycaemia, hyperlipidaemia, hyperuricaemia.
Steroids - increased hyperkalaemia risk.
Lithium - lithium toxicity
Carbamazepine - Hyponatraemia

Question 14

Describe the uses of diuretics in hypertension. (4)

Answer 14

Thiazide - vasodilator and diuresis
Spironolactone
Loop if fluid overloaded

Question 15

Describe the uses of diuretics in heart failure. (4)

Answer 15

Loop - symptom management

Spironolactone - reduces mortality

Question 16

Describe the uses of diuretics in decompensated liver disease. (3)

Answer 16

Loop and spironolactone - treats low effective circulating volume even though fluid overloaded.

Question 17

Describe the uses of diuretics in nephrotic syndrome. (4)

Answer 17

Loop - often v high doses
Thiazide
K+ sparing or K+ suppliments

Question 18

Describe the uses of diuretics in chronic kidney disease. (5)

Answer 18

Loop and thiazide - decreased GFR in CKD leads to salt and water retention - alkalosis helpful but avoid K+ sparing diuretics in CKD.

Question 19

Describe the process of diuretic resistance. (6)
Describe the end result of this. (2)
Describe the treatments for this. (3)

Answer 19

In cardiac failure there is less blood supply to the gut, so less loop diuretic is absorbed.
In CKD, there is less functional nephrons, so more filled / busy anion transporters.
In nephrotic syndrome, there is less albumin in the blood to carry it.
Causes gut oedema, which is bad because it means less can be absorbed anyway.
Lower salt intake, give furosemide IV, and find minimum inhibitory concentration.

Question 20

Describe the two types of nephrotoxicity. (2)

Answer 20

Direct damage to the renal tubular cells.

Accumulation of drugs in blood due to renal impairment.

Question 21

Name 3 nephrotoxic drugs. (3)

Answer 21

Aminoglycosides (gentamicin, vancomycin)
Aciclovir
NSAIDs

Question 22

Describe 4 drugs that can cause renal dysfunction. (4)

Answer 22

ACEi
Diuretics
NSAIDs
Metformin

Question 23

Describe the steps that need to be taken before prescribing new drugs to patients with CKD. (4)

Answer 23

Check with a pharmacist
Avoid neohrotoxins
Remember some drugs accumulate - morphine, statins, nitrofurantoin.