Diuretics 3: Potassium retaining diuretics

Question 1

2 types of Potassium sparing diuretics:

Answer 1

• Competetive antagonists of aldosterone
• Direct inhibition of Na+ influx into lumen of CCT

Question 2

Explain what should not be done, regrading potassium, when giving Potassium sparing diuretic

Answer 2

• Do not add KCL supplementation
• Do not give with ACE inhibitor, Angiotensin 1 blocker, Beta blocker or NSAIDs
• Avoid adminstrating it to patients with renal insufficiency

Question 3

Enumerate Aldosterone competing diuretics

Answer 3

• Spironolactone
• Eplerenone
• Finerenone

Question 4

Mechanism of Aldosterone competing diuretics

Answer 4

1. Compete with Aldosterone for its receptor in collecting duct
2. Decreases Na+ K+ pump
3. decreases exchange of Na+ in Lumen with K+ in the blood –> Hyperkalemia
4. Retention of Na+ in the urine –> Low efficiacy diuretic
5. Retention of some H+ –> Alkalosis
6. Increases Ca+ excretion

Question 5

Examples of Direct Na+ influx inhibtory Diuretics

Answer 5

• Triamterene
• Amiloride

Question 6

advantage of Direct Na+ influx inhibtory Diuretics over Aldosterone competing diuretics

Answer 6

They work even in absence of Aldosterone (Adrenolectomy)

Question 7

Drug of choice in ascites

Answer 7

Spironolactone

Question 8

Enumerate theraputic uses of Aldosterone competing diuretics

Answer 8

• HyperAldosteronism
• Edema associated with Hyperaldosteronism
• Heart failure
• chronic kidney disease
• Hypertension
• in combination with thiazide/loop diuretics to synergize diuretic effect
• in combination with thiazide/loop diuretics to correct hypokalemia
• Polycystic ovarian syndrome (hirsutism)

Question 9

Aldosterone inhibiting diuretics of choice when Dealing with heart failure:

Answer 9

All except spironolactone:
* Eplerenone
* Finerenone

Spironolactone antagonizes action of digitalis, worsening heart failure

Question 10

explain why Eplerenone/finerenone are used in heart failure

Answer 10

• reduced cardiac remodelling induced by Aldosterone
• improve myocardial perfusion
• decrease mortality rate after MI

Question 11

Aldosterone inhibiting diuretics of choice when it comes to chronic kidney disease

Answer 11

Finerenone

Question 12

explain how spironolactone treats hirsutism

Answer 12

By blocking Androgen receptors

Question 13

explain why eplerenone & Finerenone are more prefered than Spironolactone

Answer 13

• More selective
• no significant activity on endocrine function (androgen,progestrone, glucocorticoid) so reduced side effects

Question 14

Adverse effect of Aldosterone competing diuretics

Answer 14

• Hyperkalemia
• Low efficiancy & slow onset
• Hyperchloremic metabolic Acidosis
• Antagonises effect of Digitalis (so not used in heart failure)
• Antagonises Effect of Carbenoxolone (so not used for peptic ulcer patients)
• in Males –> gynocomastia & Impotence (block androgen)
• In females –> Menstural disturbances