Pharmacology 1 - Drugs Acting on the Kidneys 1 (main points) Flashcards
What is the action of diuretics and how do they do this?
Increase urine output through causing a net electrolyte (mainly sodium) and water loss
Give 3 examples of conditions that diuretics are used in?
Hypertension
CHF
Hepatic cirrhosis with ascites
What are the 2 ways in which diuretics can get into the filtrate?
Glomerular filtration
Secretion via transport process in the proximal tubule
Which type of drugs do organic anion transporters in the proximal tubule secrete?
Acidic drugs
What type of drugs do organic cation transporters in the proximal tubule secrete?
Basic drugs
Are thiazides and loop diuretics acidic or basic?
Acidic
Name the diuretic which is a carbonic anhydrase inhibitor?
Acetazolamide
What does acetazolamide inhibit?
Reabsorption of HCO3- in the proximal convoluted tubule
Does acetazolamide have strong or weak diuretic properties?
Weak
Name 3 loop diuretics
Furosemide
Torsemide Bumetanide
Ethacrynic acid
What part of the loop of henle do loop diuretics act on?
Ascending limb
What do loop diuretics inhibit?
what effect does this have?
Na+/K+/2Cl- cotransporter
Retention of Na+, Cl- and water in the tubule
Which type of diuretic are the most efficacious?
Loop diuretics
What part of the tubule do thiazide diuretics work on?
Distal convoluted tubule
What effect do thiazide diuretics have?
Inhibit the reabsorption of Na+ and Cl- in the distal convoluted tubule resulting in the retention of water in the tubule
Name 3 diuretics that act on the collecting duct?
Spironolactone
Amiloride
Triamterene
What type of drug is spironolactone?
Aldosterone antagonist (diuretic)
What effect does spironolactone have?
Inhibits the aldosterone-mediated reabsorption of Na+ and secretion of K+
How do amiloride and triamterene have their effects?
Block Na+ channels in the collecting duct
Aside from Na+ and K+ loss, what other ions are increasingly excreted due to loop diuretics?
Ca2+ and Mg2+
What property of loop diuretics makes them especially beneficial in pulmonary oedema caused by heart failure?
Possess an additional, indirect, venodilator action
Loop diuretics are poorly absorbed from he GI tract - true or false?
False - well absrobed
Are loop diuretics effective in severe renal failure?
Yes, they may reduce need for dialysis
Why are loop diuretics sometimes used in hypercalcaemia and renal stones?
To increase Ca2+ excretion
Name 8 side effects of loop diuretics?
Hypokalaemia Metabolic alkalosis Hypovolaemia Hypotension Depletion of calcium and magnesium Hyperglycaemia Hyperuricaemia Hearing loss
How can hypokalaemia from loop diuretic use be corrected?
Concomitant use of potassium sparing diuretics or potassium supplements
Are thiazide diuretics more or less potent than loop diuretics?
Less potent
Effect of thiazide diuretics on Ca2+ and Mg2+?
Save these
What do thiazide diuretics bind to?
Na+Cl- symporter in distal convoluted tubule
Why are thiazide diuretics especially useful in the treatment of hypertension?
Possess an additional indirect vasodilator action
What type of diuretics can be used in the treatment of nephrogenic diabetes insidious?
Thiazide
Are thiazide or loop diuretics absorbed more quickly after oral administration?
Loop (30-40 mins) vs thiazides (1 to 2 hours)
At what time of day are thiazide diuretics normally administered?
Early (to prevent diuresis interfering with sleep)
Do thiazide diuretics work in renal failure?
No - ineffective if eGFR less than 30
Name of thiazide diuretic used in mild/ moderate heart failure?
Bendroflumethiazide
Name of thiazide diuretic often used with a loop?
metolazone
Name of a long acting thiazide diuretic?
Xipamide
What type of acid base problem do thiazide diuretics cause?
Metabolic alkalosis
Effect of thiazide diuretics on K+, Na+, Mg2+ and Ca2+?
Hypokalaemia
Hyponatraemia
Hypomagensaemia
Hypercalcaemia
Effect of thiazide diuretics on glucose and lipid levels
Hyperglycaemia
Hyperlipidaemia
Can thiazide diuretics lead to gout?
Yes
Effect of thiazide diuretics on blood counts?
Can cause low blood counts
What rarer side effect can thiazide diuretics have in men?
Impotence
Would an equipotent of thiazide or loop diuretic tend to cause a greater degree of hypokalaemia?
Thiazide (Loop diuretics have a shorter duration of action = intermittent compensation)