2B : DIURETICS - POTASSIUM-SPARING DIURETICS

Question 1

2 types:

Answer 1

1. Mineralocorticoid Receptor Antagonists
2. Epithelial Na+ Channel Inhibitors

Question 2

drugs under MINERALOCORTICOIDRECEPTOR ANTAGONIST

Answer 2

(Spironolactone,
Eplerenone)

Question 3

drugs under EPITHELIAL NA CHANNEL INHIBITOR

Answer 3

(Amiloride, Triamterene)

Question 4

THERAPEUTIC USES

Answer 4

1. Hyperaldosteronism
2. Hypokalemia
3. Treatment of HFrEF
4. Drug resistant Hypertension

Question 5

HOW CAN K SPARRING DIURETICS CAN BE USE TO Hyperaldosteronism

Answer 5

• Mineralocorticoid receptor antagonists (spironolactone and eplerenone) are useful in
  blunting the symptoms produced by states of mineralocorticoid excess
  (due to primary or secondary causes (including heart failure)

Question 6

Treatment
of HFrEF

Answer 6

• Mineralocorticoid
  receptor antagonists have been found to preserve cardiac function in the setting of coronary ischemia, an effect that reduces the rate of progression of systolic heart failure
• The RALES trial 1995 98 showed that spironolactone administration in patients with severe heart failure reduced mortality by 27 percent and also reduced the rate of hospitalization and improved symptoms
• Recent studies indicate that they are of little benefit in patients with diastolic dysfunction HFpEF

Question 7

Drug
resistant Hypertension

Answer 7

Treatment resistant hypertension is often caused by excessive Na retention A recent clinical trial found spironolactone to be superior to non diuretic add on drugs at lowering
blood pressure (Williams et al, 2015

Question 8

PSD: ADVERSE EFFECTS

Answer 8

• Hyperkalemia
• Gynecomastia (only for spironolactone)

Question 9

how can Spironolactone cause gynecomastia
(enlargement

Answer 9

• due to effects on estrogen steroid
  receptors .
• Due to its greater selectivity for mineralocorticoid receptors, eplerenone has not been associated with this side effect.

Question 10

• Is a synthetic steroid
• Sole diuretics that do not require access to tubular lumen to induce diuresis

Answer 10

PSD: SPIRONOLACTONE

Question 11

MOA: antagonizes action of aldosterone in CT with slower onsets /offsets of action (24 to 72h)

Answer 11

PSD: SPIRONOLACTONE

Question 12

Therapeutic use of Spironolactone

Answer 12

1. EDEMA and HTN
2. PRIMARY HYPERALDOSTERONISM
3. REFRACTORY EDEMA
4. RESTORE K+

Question 13

Therapeutic use:

EDEMA and HTN

Answer 13

usually in combination
with thiazide or loop diuretics

Question 14

Primary hyperaldosteronism

Answer 14

(aldosteronism + excessive Na+ delivery to distal sites –> renal K+ wasting)

Question 15

Refractory edema

Answer 15

associated with 2ndary aldosteronism (cirrhosis, HF, ascites)

Question 16

Restore K+
levels in patients with hypokalemia

Answer 16

2ndary to hyperaldosteronism

Question 17

PSD: Eplerenone DOSAGE

Answer 17

25 TO
100 mg OD
BID

Question 18

MOA OF EPLERENONE

Answer 18

antagonizes action of
aldosterone in CT with slower
onsets/offsets of action (24 72h)

Question 19

PSD: Amiloride DOSAGE

Answer 19

5 TO
20 mg OD

Question 20

CLASSIFICATION OF AMILORIDE

Answer 20

EPITHELIAL SODIUM CHANNEL INHIBITORS

Question 21

MOA of AMILORIDE

Answer 21

• block as ENaC in LM of principal cells in late distal tubules and collecting ducts bycompeting with Na+ for negatively charged
  areas within the pore of the Na+ channel
• inhibit Na K exchange mechanism in CT(12 to 24h)

Question 22

Common adverse effects of amiloride

Answer 22

• HYPERKALEMIA- most dangerous
  effect
• Nausea and vomiting
• Diarrhea
• Headache

Avoid in patient with renal failure, AIDS patient receiving pentamidine and trimethoprim

Question 23

PSD: Triamterene dosage

Answer 23

25
100 mg OD

Question 24

classification of triamterene

Answer 24

Epithelial Na+ Channel Inhibitors

Question 25

MOA of triamterene

Answer 25

• block as ENaC in LM of principal cells in late distal tubules and collecting ducts by competing with Na+ for negatively charged
  areas within the pore of the Na+ channel
  (same with amiloride)
• inhibit Na K exchange mechanism in CT (12 24h)

Question 26

Common adverse effects of triamterene

Answer 26

• Nausea and vomiting
• Leg cramps
• Dizziness
• Kidney stones
• Folic acid antagonist–>megaloblastosis
• Reduce glucose tolerance
• Photosensitization
• Nephritis
• Avoid using this with:
  Triamterene + indomethacin = ARF

Question 27

PSD: Triamterene Contraindications

Answer 27

• If taking K+ supp, ACE
  I and BB, NSAIDS
• Pxs with CHRONIC RENAL
  INSUFFICIENCY
• Pxs with LIVER DISEASE

Question 28

Traimterene Therapeutic Use

Answer 28

• Combination with other diuretics
  (augment other diuretic)
• Antikaliuretic effects of loop diuretic and thiazide