Canonical Question

Renal Pharm – Diuretics

V5 E3.i Historical V4 H3.i 1 appearance

Master answer

Sites and Mechanisms of actions of diuretics

LocationDrugMechanism of ActionAdverse Effects
PCTAcetazolamidePrevents the intracellular conversion of CO2 and H2­O to H2CO3­­
→ Resulting HCO3 usually reabsorbed via Na/HCO3 co transporter therefore decreased HCO3 leads to decreased Na reabsorption
→ decreased reabsorption of water		Metabolic acidosis
Renal stones
Hyponatraemia
LoHFrusemideInhibits Na/K/2Cl transporter on luminal membrane preventing ion reabsorption
→ increases osmolality of luminal fluid
→ decreased osmotic gradient for water reabsorption  		Hypochloraemic metabolic alkalosis
Hyponatraemia
Hypokalaemia
Hypomagnesaemia
DCTThiazideInhibits Na/Cl transporter on the luminal membrane preventing Na and Cl reabsorption
→ increases osmolality in luminal fluid
→ decreased osmotic gradient for water reabsorption  		Hypochloraemic metabolic alkalosis
Hyponatraemia
Hypokalaemia
Dyslipidaemia
Hyperglycaemia
CDSpironolactonePrevents activity of aldosterone
→ Decreased ENaC channels for Na reabsorption in the collecting duct and decreased Na/K ATPase activity in collecting duct
→ Prevents Na reabsorption and consequently reduced osmosis  		Gynaecomastia
Hyperkalaemia
Renal stones
OtherMannitolIncreases osmolality of of luminal fluid
→ decreases osmotic gradient for H2O reabsorption		Hypotension
Tachycardia
Thrombophlebitis
Convulsions

CICMWrecks 2019

Further Reading:

Click to Open CICMWrecks Table: Diuretics

Exam appearances

ExamExact wordingRelationshipSuccess
2007B Q02 Outline the sites and mechanisms of action of diuretics. Give one example of drug acting at each site and list two side effects for each drug. historical_member —