Diuretics And Renal Pharmacology Flashcards
What is the renal physiology mnemonic?
REEM
Regulatory (fluid balance, acid-base balance, electrolyte balance)
Excretory (waste products (protein metabolism), Drug elimination (glomerular filtration, tubular secretion))
Endocrine (renin, EPO, prostaglandins, 1-alpha calcidol)
Metabolism (vitamin D, polypeptides (insulin), Drugs (morphine, paracetamol))
What drugs act on the renal tubules?
Carbonic anhydrase inhibitors Osmotic diuretics Loop diuretics Thiazides Potassium sparing diuretics Aldosterone antagonists ADH antagonists
What is mannitol and how does it work?
An osmotic diuretic (is just present to create an osmotic pull)
Loss of water
Reduced intracellular volume
Hypernatrimia risk
What type of diuretic is ferosomide?
Loop diuretic
How do loop diuretics work?
Loss of Na and water
Hypokalaemia metabolic acidosis
Increased Ca2+ loss
Who do you not give thiazides do?
Patients with hyperkalaemia
How do thiazide diuretics work?
Loss of Na and water
Hypokalemic metabolic acidosis
Increased Ca2+ reabsorbtion
How does aldosterone work?
Aldosterone increases expression of ENaC and Na+K+ATPase in principle cells of the collecting duct.
Hold into salt
Amiloride and Spironolactone
Both reduce Na+ in and K+ out of collecting duct but in different ways.
Why does alcohol make you want to wee?
As inhibits ADH release
Why does caffeine make you want to wee?
Increase GFR and decrease tubular Na+ reabsorbtion
Give examples of ADH antagonists
Lithium -diuretic nut not natriuretic. Inhibits action of ADH.
Tolvaptan - ADH antagonist. Diuretic but not netriuretic. Used to treat hyponatremia and prevent cyst enlargement in APCKD.
What are the ADRs for diuretics?
Hypovolaemia and hypotension -active RAAS, lead to AKI
Electrolyte disturbance (Na+, K+, Mg2+, Ca2+)
Metabolic abnormalities
Anaphylaxis / photosensitive rash ect. (rare)
What are the side effects of thiazides?
Gout Hyperglycaemia Erectile dysfunction Increase LDL and TG Hypercalcaemia
What are the side effects of ferosimide?
Ototoxicity
Alkalosis
Increase LDL and TG
Gout
What are the side effects of Spironolactone?
Hyperkalaemia
Impotence
Painful gynaecomastia
What are the side effects of bumetanide?
Myalgia
What diuretics do ACEi interact with and what are the effects?
K+ diuretic
Increase hyperkalaemia - cardiac problems
What diuretics do Aminnoglycosides interact with and what are the effects?
Loop diuretics
Ototoxicity and nephrotoxicity
What diuretic does digoxin interact with and what are the effects?
Thiazide and loop
Hypokalaemia - increased digoxin binding and toxicity
What diuretics do B-blockers interact with and what are the effects?
Thiazide diuretics
Hyperglycaemia, hyperlipidaemia, hyperuricaemia
What diuretics do Steroids interact with and what are the effects?
Thiazide and loop diuretics
Increased risk of hypokalaemia
What diuretics does Lithium interact with and what are the effects?
Thiazide and loop diuretics.
Lithium toxicity (thiazides), reduced lithium levels (loop)
What diuretics does Carbamazepine interact with and what are the effects?
Thiazide diuretics.
Increased risk of hyponatraemia.
What diuretics can you use to treat hypertension?
Thiazide diuretics
Spironolactone
Loop if fluid overload
What diuretics can you use to treat heart failure?
Loop diuretics (these will not improve the prognosis but patients will feel symptomatically better)
Spironolactone (this has non-diuretic benefits so the patients will feel better and it deceases mortality)
What diuretics do you use for decompensated liver disease?
Spironolactone
Loop diuretics
What diuretics can you use for nephrotic syndrome?
Loop diuretics (large doses)
Maybe thiazides
Maybe K+ sparing diuretics / K+ supplements
How do you treat CKD?
Need diuretics as the decrese in GFR leads to salt and water retention.
Loop diuretics
Maybe thiazide diuretics
The alkalosis and the kalliuretic effects are potentially beneficial.
Avoid K+ sparing diuretics
Describe how diuretics get delivered to the renal tubule
Ferosimide delivered to basolateral side of the PCT.
Ferosimide actively secreted into tubular lumen by organic anion transporter.
Ferosemide delivered to Luminal side of the TAL, including diuresis.
Why is salt bad?
As if you eat salt, it counteracts the effects of diuretics.
Causes oedema
What is refractory oedema and how do you treat it?
Refractory oedema is defined as peripheral oedema that does not respond to dietary sodium restriction and combined diuretic treatment including a loop diuretic, often caused by an evident underlying cardiac or pulmonary condition.
Check salt intake
Give ferosimide iv if gut oedema likely
Find minimum effective dose
Give repeated bolus or infusion.
Why can you have different electrolytes when similar doses of directs?
As although loosing same salt and K, loosing loss water.
So when gfr causes changes in electrolytes in thiazide more than ferosamides.
What drugs are Nephrotoxic?
Aminoglycosides e.g. gentamicin Vancomycin (I.V. only) Acyclovir NSAIDs Ect...
What drugs can cause problems with renal dysfunction?
ACEi
Diuretics
NSAIDs
Metformin
How do ACEi and NSAIDs affect renal perfusion?
NSAIDs - prevent vasodilation of afferent arteriole by prostaglandins
ACEi prevents vasoconstriction of efferent arteriole by Ang II.
How do you prescribe in patients with CKD?
Avoid nephrotoxins.
If gentamicin / vancomycin required - dose carefully and ask pharmacist.
Check with pharmacist if drugs need dose altering.
Side effects common drugs are increased with renal disease because of the accumulation of metabolites.
What are some causes of hyperkalaemia?
Excess intake (virtually never the only cause)
Movement out of cell (acidosis, hypertonicity, tissue (esp muscle) damage)
Reduced urine loss (reduced GFR, reduced distal delivery of Na+, reduced secretion in collecting duct)
Drugs (RAAS inhibitors, NSAIDs, ENaC blockers)
What are the ECG changes of hyperkalaemia?
Tall, symmetrical T waves Small or absent P waves Increased P=R interval Wide QRS complex Sine wave pattern Asystole.
How do you manage hyperkalaemia?
Identify cause
ECG
Treat:
Protect the heart - calcium gluconate (not reduce K)
Lower serum K+ - Insulin / Dextrose
Remove K+ from body - calcium resonium
