L4 - Diuretics Flashcards
Diuretic
Increased urine production
Natriuretic
Loss of sodium in urine
Aquaretic
Loss of water without electrolytes
Carbonic anhydrase inhibitor mechanism of action
Inhibit carbonic anhydrase in the PCT Inhibits: - HCO3- reabsorption - Na+ reabsorption via sodium/ HCO3- cotransporter in the PCT therefore more delivered to the EnaC channels distally - therefore more K+ is secreted
When are carbonic anhydrase inhibitors used
In glaucoma and mountain sickness
Side effects on carbonic anhydrase
Metabolic acidosis
Hypokalaemia
Name of osmotic agent
Mannitol
Osmotic agent mechanism of action
- Osmolarity is more negative in the lumen due to mannitol therefore water is diffused out of the tubule down the osmotic gradient
- Increased diuresis without electrolyte loss therefore urine is more dilute
- acts everywhere in the nephron especially the PCT
- Reduces intracellular pressure
When are osmotic agents used
Raised intracranial pressure in ITU - intensive treatment unit
Osmotic agent side effects
- hypernatremia
- dehydration
SGLT 2 inhibitors mechanism of action
- inhibits glucose and Na+ reabsorption in the PCT
- more Na+ delivered to the ENaC channels distally in the DCT and collecting duct
- therefore more K+ secreted
- more Na+ delivered to the macula densa in the DCT therefore RAAS not activated
- increased uric acid secretion
When are SGLT 2 inhibitors used
Diabetes
Hypertension
Hyperuricaemia
SGLT2 inhibitor effects
Decrease plasma glucose Decrease body weight Decrease blood pressure Decrease plasma uric acid Decrease glomerular hyperfiltration
Loop diuretic mechanism of action
- Inhibits the NKCC2 channel in the ascending limb of the loop of Henle
- decreases Na+ and K+ reabsorption
- decreased ROMK function
- decrease Mg2+ and Ca2+ reabsorption
- more Na+ delivered to ENaC therefore more K+ secreted
What percentage of sodium is reabsorbed in ascending limb of the loop of Henle
25%
When is furosemide given
Heart failure
Hypertension
Hyperkaleamia
Hypercalcaemia
Effects of furosemide
- loss of water and sodium
- loss of Ca2+
- hypokalaemic metabolic alkalosis
Thiazides diuretic mechanism of action
- Inhibits Na+ Cl- co transporter in the DCT
- Facilitates the NCX to reverse therefore Na+ is transported from the blood the the tubule and Ca2+ is reabsorbed into blood
- increased Ca2+ reabsorption (also stimulated by PTH)
- more Na+ is delivered to ENaC channels in the collecting duct therefore more K+ is secreted
What percentage of sodium is reabsorbed in the DCT?
5%
Effects of thiazides diuretics
Loss of water and sodium
Hypokalaemic metabolic alkalosis
Increased calcium reabsorption
Thiazide side effects
Hypokalaemic metabolic alkalosis Hyperuricaemia - gout Arrhythmia Hyponatraemia Hyperglycaemia- Increased glucose uptake - with beta blocker Increased cholesterol and triglyceride - bad for diabetics Erectile dysfunction Hypercalcaemia