3.2 Diuretics And Renal Pharmacology Flashcards
What is renal physiology ?
Regulatory
- fluid balance
- acid base balance
- electrolyte
Excretory
- waste
- drug elimination
Endocrine
- renin
- erythropoietin
- prostaglandins
- 1- alpha calcidol
Metabolism
- vit d
- polypeptides (insulin)
- drugs (morphine and paracetamol)
REEM
What is sodium reabsorbed with in the PCT?
Bicarbonate
If stopped e.g by carbonic anhydrase inhibitors get too much bicarbonate so can get alkyalosis
Why do diabetics urinate a lot?
Glucose as as an osmole and pulls the water in through your tubule.
What ions do loop diuretics particularly effect?
Loose calcium and magnesium
As a result get hydrogen loss = become Alkylotic
Thiazides diuretics mode of action?
Increase calcium absorption
NB: Never give to a hypercalcaemic !!!!!!
How does caffeine have a diuretic action?
Increase GFR
Decrease tubular Na reabsorption
Name 2 ADH antagonists
Lithium - diuretic but not natriuretic. inhibits ADH action. Toxic if given with a thiazides
Tolvaptan - ADH antagonist. Diuretic, not natriuretic. Used to treat hyponatraemia (and prevent cyst enlargement in acute polycystic kidney disease)
What are some general adverse drug reactions of diuretics?
Hypovolaemia and hypotension
- activates RAAS
- can lead to AKI
Electrolyte disturbance
Metabolic abnormalities
Anaphylaxis/photosensitivity
Adverse effects of thiazides?
- Gout
- Hyperglycaemia
- Erectile dysfunction
- ↑
Adverse effects of furosemide?
- Ototoxicity
- Alkalosis
- ↑
Adverse effects of spironolactone?
- Hyperkalaemia
- Impotence
- Painful gynaecomastia
Hypertension treatments used?
- Thiazides
- Spironolactone if cause has to do with aldosterone root
- Loop diuretics (only if you have too much fluid)
Heart failure treatments?
Heart failure = usually have more fluid
- loop diuretics
- spironolactone = reduces mortality and has diuretic effect
They combat each others side effects also
Decompensated liver disease treatment?
- spironolactone
- loop diuretics
Nephrotic syndrome treatments?
- loop diuretics
- maybe thiazides
- maybe K sparing diuretics or K supplements
Why do you get salt and water retention in CKD ?
Decreased GFR
Why would you give IV treatment of diuretics in gut oedema instead of orally?
You don’t have good absorption so IV is useful
How would you monitor refractory oedema?
Check salt intake
Give furosemide IV if gut oedema likely
Find minimum effective dose
Give repeated bolus or infusion
What are the side effects of carbonic anhydrase inhibitors?
Acidosis or renal stones
Typically not used as a diuretic as a result, mainly in glaucoma and altitude sickness
Name some potentially nephrotoxic drugs
Aminoglycosides e.g gentamicin
Vancomycin
Acivlovir
NSAIDS
Causes of hyperkalaemia?
- excess intake
- movement out of cells e.g acidosis, hypertonicity, tissue damage
- reduced urine loss e.g reduced GFR, distal Na+ delivery and reduced secretion in collecting duct
- drugs e.g RAAS inhibitors
What ECG changes are seen in hyperkalaemia?
Progressive change
- tall T waves
- small/absent P waves
- increased P/R intervals
- wide QRS complete
- sine wave pattern
- asystole
Needs IMMEDIATE action
Treatment of hyperkalaemia?
1) protect heart with - calcium gluconate (stops heart reacting with potassium)
2) lower serum k+ with - insulin and dextrose
3) remove k+ from body with - calcium resonium
How does oral furosemide reach the loop of Henley?
Furosemide taken as a tablet is bound to albumin and absorbed from your stomach into the blood stream. It then enters the lumen of your kidney tubule through proximal epithelial tubule cells.
From there it can move to the loop of Henley where it can act of the sodium potassium chloride channels.
Why does furosemide not work in patients with
- Heart failure
- CKD
- nephrotic syndrome ?
If your pump doesn’t work e.g due to heart failure, furosemide wont get round bloodstream as well so wont get to where it needs to be
Chronic kidney disease = less nephrons around, less tubules for furosemide to cross across. Also, more competition for use of transporters for other substances since there are less nephrons = harder for furosemide action to occur.
Nephrotic syndrome, don’t have very much protein in your blood. Furosemide doesn’t have anything to bind to to get across via bloodstream.
What blocks the effect of prostaglandins on your afferent arteriole?
NSAIDS prevent the vasodilatory effect of prostaglandins
