Diuretics Flashcards
What is the mechanism of action of Thiazide diuretics?
- Inhibiton of NaCl symporter
- Inhibits NaCl reabsorption in distal convuluted tubule
When are thiazide diuretics used?
-Hypertension (Used for vasodilation and diuresis)
What are the side effects of thiazide diuretics?
- Gout
- Hyperglycaemia
- Erectile Dysfunction
- Increase in LDL and Triglycerides
- Hypercalcaemia (promotion of Ca reabsorption)
- Hypokalaemia
- Hyperuricemia
- Impotence
What are the examples of Loop Diuretics?
- Furosemide
- Bumetanide
What is the mechanism of action of Loop Diuretics?
- Affects the thick ascending limb of the Loop of Henle
- Inhibits NaCl reabsorption
When are Loop Diuretics used?
- Heart failure
- Decompensated Liver Disease
- Nephrotic Syndrome
- Chronic kidney Disease (+/- thiazides sometimes as a boost)
- Oedema (+/- hypertension in advanced CKD)
(Hypertension - less used due to shorter duration of action)
What are the side effects of Furosemide?
- Ototoxicity
- Alkalosis (Blunt H+ secretion)
- Increase in LDL and triglycerides
- Gout
- Ca2+/Mg excretion
- Hypokalaemia (Blunt K+ secretion)
- Androgen cross-reactivity
- Metabolic effects
What are some side effects of Bumetanide?
- Myalgia
- Alkalosis
What is the mechanism of action of Spironolactone?
- Inhibits Na retention by antagonising aldosterone. (3Na+/2K+ and Na+reflux)
- Works via the eNaC
What are the uses of Spironolactone?
- Hypertension (primary drug for primary hyperaldosteronism)
- Decompensated Liver Disease
- Heart failure
- Ascites
- Hyperadrenalism
What are the side effects of Spironolactone?
-Hyperkalaemia
-Impotence
-Painful gynaecomastia
Don’t use in CKD
What is the mechanism of action of carbonic anhydrase inhibitors?
- Inhibits the enzyme carbonic anhydrase
- Leads to excretion of Na+, K+ and PO3
What are uses of carbonic anhydrase inhibitors?
- Glaucoma
- Altitude sickness
What are the side effects of carbonic anhydrase inhibitors?
- Metabolic Acidosis
- Hypokalaemia
- Acidosis
- Renal stone
What is the mechanism of action of osmotic diuretics (mannitol)?
- Filtered at glomerulus
- Increases osmotic gradient throughout nephron
What are the uses of osmotic diuretics?
-Reduce high intracerebral pressure
What are the side effects of osmotic diuretics?
- Excessive water loss
- Hypernatremia
- Allergic Reactions
What is the mechanism of action of lithium (ADH antagonists)?
- Inhibits action of ADH
- Diuretic but not natriuretic
Reduces concentrating ability of urine in collecting ducts
When are ADH antagonists used? (lithium, tolvaptan)
- Hyponatraemia
- Prevention of cyst enlargement in APCKD
What are the side effects of ADH antagonists?
- Hypernatremia
- Deranged liver function
What are the general side effects of diuretics?
- Anaphylaxis/Photosensitivity rash
- Hypovolaemia and hypotension (Activation of RAAS which can lead to acute kidney injury)
- Electrolyte Disturbance (Na+, K+, Mg2+, Ca2+)
- Metabolic abnormalities (depends on individual drug)
Why do some patients fail to respond to diuretics?
- Oedema of the gut so less absorption
- Heart failure so less delivery of the diuretic
- The nephrons are affected so work less well
How do you treat diuretic resistance due to oedema of the gut?
Give multiple doses to find the minimum effective dose
What are some potentially nephrotoxic drugs?
- Aminoglycosides
- Vancomycin
- Aciclovir
- NSAIDs
