A short review by Dr. SWETHA RANI AITHA YOUTUBE LINK FOR AUDIO AND VIDEO-https://youtu.be/-RGFCtwKXu0

1. POTASSIUMSPARING DIURETICS

2. • Potassium sparing diuretics are sulfonamides with weak diuretic property.
DRUGS:
• These drugs are further classified into the following-
Aldosterone receptor blockers Epithelial Na+ channel
blockers
(ENaCs)
• Spironolactone
• Eplerenone
• Amiloride
• Triamterene
SEAT
INTRODUCTION

3. LOOP
OF HENLE
GLOMERULUS
PCT
MECHANISM OFACTION
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L
L
E
C
T
I
N
G
D
U
C
T
PRINCIPAL
CELL
Na+-K+-ATPase pump
ENaC-
channel
COLLECTING
DUCT
Na+
Na+
Na+
INTERSTITIUM
K+
K+
K+
channel
Aldosterone
Aldosterone MR
MR-Mineralocorticoid receptor
AIPs
Spironolactone
Triamterene
Amiloride

4. PHARMACOKINETICS
Aldosterone antagonists:
• Slow onset with prolonged duration of action.
• Highly plasma-protein bound.
• High 1st pass metabolism.
• Toxic in hepatic &renal failure due to formation of active metabolites.
Epithelial Sodium Channel Blockers:
• Bioavailability of Triamterene & Amiloride is 50%and 20% respectively.
• Triamterene is metabolized to 4-hydroxytriamterene(toxic in hepatic and renal
failure) and is excreted in urine.
• Amiloride is excreted unchanged in urine.

5. DOSAGE
SPIRONOLACTONE 25 to 50 mg, BD-QID, max
dose-400mg/day
EPLERENONE 25 to 50 mg, BD
TRIAMTERENE 50 to 100 mg per day
AMILORIDE 5 to 10 mg, OD-BD

6. PHARMACODYNAMICS
• Produce mild diuretic effect due to mild increase in excretion of Na+ and Cl- .
• Urinary excretion of K+ , H+, Ca2+ , Mg2+ is decreased.
• Hyperuricemia occurs on chronic use due to enhanced reabsorption of uric acid
in PCT and reduced excretion.

7. CLINICAL USES
ALDOSTERONE ANTAGONISTS:
• Essential hypertension
• Heart failure
• Hirsutism.
• Oedema(Primary hyperaldosteronism-Conn’s syndrome, Hepatic cirrhosis,).
• Spironolactone is the drug of choice for Refractory ascites.
• Nephrotic syndrome
• PCOS
H
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PLZ
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8. CLINICAL USES
ENaC blockers:
• Amiloride is the DOC in Lithium toxicity.
• Other uses like, Lithium induced nephrogenic DI, Liddle’s syndrome
• Essential Hypertension in combination with other diuretics.
• Pseudo aldosteronism
H
P
L
C Cystic fibrosis

9. ADVERSE EFFECTS
H
H
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D
Hyperkalemia
Hyperchloremic
metabolic acidosis
Headache
Nausea
CNS side effects
Diarrhea

10. ADVERSE EFFECTS OF TRIAMTERENE
Triamterene causes-
Dizziness
Megaloblastic anemia
Photosensitivity
Renal stones
Interstitial nephritis
P
R
I
D

11. CONTRA INDICATIONS
• Patients with renal failure, hepatic failure and hyperkalemia.
• Spironolactone should be avoided in patients with Peptic ulcer disease and
Gastritis.
• Use of two K+Sparing Diuretics should be avoided.
• K+sparing diuretics should be avoided in patients on β- blockers or
ACEI.
PRECAUTIONS
B
A
D
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G

12. NSAIDS inhibit the action of Spironolactone and Triamterene.
The clearance of Digoxin is inhibited by Spironolactone.
Salicylates decrease diuretic activity of spironolactone.
DRUG INTERACTIONS
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