Drugs and The Kidney Flashcards
Which drugs can be secreted into the lumen?
Weak acids or bases
Describe akalinisation and how this is achieved clinically
Alkalinisation increases the pH of the urine which deprotonates weak acids in the lumen which traps them, increasing excretion. Achieved using acetazolamide or bicarbonate infusion
What are the pharmacological consequences of renal failure?
Renally excreted drugs will have a longer half life
Hyperkalaemia
Hyperphosphataemia
Uraemia
Name six classes of diuretic
Carbonic anhydrase inhibitors Loop diuretics Potassium sparing diuretics Thiazide diuretics Osmotic diuretics Aquaretics
Describe the mechanism of carbonic anhydrase inhibitors
Inhibition if carbonic anhydrase, increasing bicarbonate levels in the urine
Give an example of a carbonic anhydrase inhibitor
Acetazolamide, methazolamide
What compensates for carbonic anhydrase inhibitors?
Compensated by macula densa and and distal tubule
Describe the mechanism of loop diuretics
Inhibits Na/K/Cl transporter in the thick ascending limb and macula densa cells to increase osmolarity and therefore water excretion.
Inhibition in macula densa cells decreases tubuloglomerular feedback
Give an example of a loop diuretic
Furosemide, bumetanide
Give an example of a thiazide diuretic
Hydrochlorothiazide, bendrofluazide
What is the mechanism of a thiazide diuretic?
Blocks the Na/Cl cotransporter to decrease salt reabsorption and therefore increase water excretion
Why may potassium supplements be given alongside a thiazide diuretic?
They increase potassium secretion which may lead to hypokalaemia
What is the mechanism of spironolactone?
Aldosterone antagonist
What is the mechanism or amiloride?
Inhibition of ENaC channels
What is the mechanism of osmotic diuretics?
Increasing the tubular osmolarity to extract water
