Potassium-sparing diuretics are categorized into aldosterone receptor blockers and epithelial Na+ channel blockers, including drugs like spironolactone, eplerenone, amiloride, and triamterene. They are used for various conditions such as hypertension, heart failure, and hirsutism, but can cause side effects like hyperkalemia and metabolic acidosis. Precautions include avoiding use in patients with renal or hepatic failure, and caution with other medications like β-blockers and ACE inhibitors.

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
E
C
T
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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
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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
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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
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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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