Lecture 6: Diuretic Agents Flashcards
what is reabsorption of water very dependent on
Na+
what is the main site of action of carbonic anhydrase inhibitors
proximal tubule
what is the main site of action of osmotic diuretics
- proximal tubule
- descending loop of henle
what is the main site of action of thiazides and thiazide like diuretics
early distal tubule
what is the main site of action of potassium sparing diuretics
- late distal tubule
- early collecting tubule
example of a loop diuretic
furosemide
how do loop diuretics work
- inhibit NKCC2 transporter in the thick ascending limb of loop of henle
- reduced Na+ reabsorption leads to profound diuresis
unwanted effects of loop diuretic use
- dehydration
- hypokalaemia
- metabolic alkalosis
- hypokalaemia can potentiate effects of cardiac glycosides
- deafness when used with aminoglycoside antibiotics
where do thiazide diuretics act
- distal tubule
- on Na+/Cl- cotransporter
examples of thiazide diretics
- bendroflumethiazide
- hydrochlorothiazide
examples of thiazide like diuretics
- indapamide (preferred for hypertension)
- metolazone (good combined with loop diuretic)
- xipamide (lowers BP with less side effects)
unwanted effects of thiazide diuretics
- plasma K+ depletion
- metabolic alkalosis
- increased plasma uric acid and gout
- hyperglycaemia
- increased plasma cholesterol with long term use
- reverisble male impotence
what is the current preferred diuretic for resistant hypertension
indapamide
symptoms of mild hypokalaemia
- fatigue
- drowsiness
- dizziness
- muscle weakness
symptoms of severe hypokalaemia
- arrhythmias
- muscle paralysis
- death
examples of aldosterone antagonists
- eplerenone
- spironolactone
examples of non-aldosterone antagonists
- amiloride
- triamterene
what is the active metabolite of spironolactone
canrenone
what are aldosterone antagonists used for
- oedema
- heart failure
unwanted effects of aldosterone antagonists
- hyperkalaemia
- metabolic acidosis
- GI upsets
- gynaecomastia, menstrual disorders, testicular atrophy
how do non-aldosterone antagonists work
block luminal Na+ channel on distal tubule
unwanted effects of non-aldosterone antagonists
- hyperkalaemia
- metabolic acidosis
- GI issues
- skin rashes
example of carbonic anhydrase inhibitor
azetozolamide
what are carbonic anhydrase inhibitors used for
- glaucoma
- epilepsy
unwanted effects of carbonic anhydrase inhibitors
- metabolic acidosis
- enhances renal stone formation
what were the potential ADH antagonists
- lithium
- demeclocycline
- now developing tolvaptan
issue with the ADH antagonists
- can cause diabetes insipidus
- can cause renal failure
- lithium can cause tremors, mental confusion, cardiotoxicity
- demeclocycline shouldn’t be used in patients with liver disease
what is tolvaptan being used for
- treatment of hyponatriuraemia
- in fast track clinical trials for polycystic kidney disease
