Diuretics Flashcards
What are the main physiological roles of kidneys
Regulation: Fluid, electrolytes, acid base
Excretion: metabolites, Drugs
Endocrine: renin, Erythropoietin
Metabolism: Vitamin D, insulin, PTH
What are the types of commonly used diuretics
Loop
Thiazide
K sparing diuretics
Aldosterone antagonists
What are types of rarely used diuretics
Carbonic anhydrase inhibitors
Osmotic diuretics
ADH antagonists
What are Drugs that have diuretic-like effects
Digoxin
Amiloride
What is mechanism of action of carbonic anhydrase inhibitors
Inhibit carbonic anhydrase at PCT
Inhibit Na reabsorption
What are side effects of carbonic anhydrase inhibitors
Metabolic acidosis (bicarb loss) Hypokalaemia
What is Carbonic anhydrase inhibitors indicated
Glaucoma
What is mechanism of action of osmotic diuretics
Freely filtered and poorly reabsorbed
Increases filtrate osmolality
Draws water into filtrate down osmotic gradient
When is osmotic diuretics indicated
Cerebral oedema
Pulmonary oedema
What are side effects of osmotic diuretics
Hypovolaemia
Hypernatraemia
What is mechanism of action of ADH Antagonists
Inhibit ADH receptors at DCT and CD
Inhibit water reabsorption
What are types of ADH antagonists
Lithium
Demeclocycline
What is mechanism of action of digoxin
Inhibit Na/K+ ATPase
When is digoxin indicated
Atrial fibrillation
Has a mild diuretic effect
Give examples of loop diuretics
Furosemide
Bumetanide
What is mechanism of action of Loop diuretics
Inhibit NKCC2 co transporter at thick ascending limb
Inhibit Na reabsorption (25%)
Inhibit K reabsorption
When is loop diuretics indicated
Heart failure
Liver failure
What are side effects of loop diuretics
Hypokalaemia
Hypokalaemic metabolic alkalosis
Ototoxicity
What are drug interactions with loop diuretics
Aminoglycosides: ototoxicity, nephrotoxicity
Steroids: hypokalaemia
Digoxin: hypokalaemia, digoxin toxicity
Give examples of thiazide diuretic s
Bendroflumethiazide
Thiazide-like diuretics: chlortalidone, metolazone
What is mechanism of action of thiazide diuretics
Inhibit NaCl co transporter at DCT
Inhibit Na reabsoprtion
Decreased Ca excretion
Decreased Uric acid excretion
What are indications of thiazide diuretics
Hypertension
Heart failure
Kidney stones
What are side effects of thiazide diuretics
Hypokalaemia Hyponatraemia Hypercalcaemia Hyperuricaemia Gout Erectile dysfunction
What are drug interactions of thiazide diuretics
Steroids
Digoxin
Beta blockers - hyperglycaemia, hyperlipidaemia
Carbemazepine - hyponatraemia
What are types of K sparing diuretics
Amiloride
Aldosterone antagonists
What is mechanism of action of amiloride
Inhibit ENaC at DCT + CD
Inhibit Na reabsorption (2%)
Inhibit ROMK activity
Reduce K excretion
When is amiloride indicated
Add-on therapy to K-losing diuretics
What are drug interactions with amiloride
Ace-inhibitors: Hyperkalaemia
Give examples of aldosterone antagonists
Spironolactone
Eplerenone
What is mechanism of action of spironolactone
Inhibit aldosterone binding to Mineralocorticoid receptors at DCT + CD
Inhibit Na/K ATPase and ENaC synthesis
Inhibit Na reabsorption
Reduce K excretion
When is spironolactone indicated
Hypertension
Heart failure
Liver failure
Hyperaldosteronism
What are side effects of spironolactone
Gynaecomastia
Hyperkalaemia
What are the general side effects of diuretics
Hypersensitivity - Anaphylaxis, rash
Hypovolaemia, postural hypotension
Electrolyte imbalance
Metabolic disturbance
What are causes of diuretic resistance
Patient in compliance High Na intake Volume depletion NSAID Incomplete treatment of primary disorder
What are issues of prescribing drugs in renal disease
Drug Nephrotoxicity
Accumulation of drugs to toxic levels
What are prescribing rules in renal disease
Avoid nephrotoxins
Monitor U+Es and renal function
Use lower dose according to GFR
Give examples of nephrotoxic drugs
Ace inhibitors NSAIDs Aminoglycosides Penicillin Metformin
What are prescribing rules in the elderly with renal disease
Renal function overestimated
Start at low dose, titrate slowly
Polypharmacy is common
Cautious of DDIs
