Diuretics work by inhibiting reabsorption of sodium and water in the kidneys, increasing urine output. There are several types of diuretics that act in different parts of the kidney: loop diuretics act in the ascending limb of Henle's loop, thiazide diuretics act in the distal convoluted tubule, and potassium-sparing diuretics act in the cortical collecting tubule. Diuretics are used to treat conditions like heart failure, liver failure, renal failure, and hypertension by mobilizing edema fluid and maintaining urine volume. Common side effects include hypokalemia, hyperglycemia, and increased uric acid levels.

1. DIURETICS
Dr.SOOKUN R.K

2. Definition
 Diuretics (saluretics) elicit increased production of urine
(diuresis) with a direct renal action.The predominant
action of such agents is to increase urine excretion by
inhibiting the reabsorption of NaCl and water.
Purpose of Using Diuretics
1. To maintain urine volume ( e.g.: renal failure)
2. To mobilize edema fluid (e.g.: heart failure,liver failure, nephrotic syndrome)
3. To control high blood pressure.

3. Types of Diuretics
 Loop Diuretics
 Salidiuretics (thiazides and their analogues)
 Potassium sparing Diuretics
 Osmotic Diuretics
 Carbonic anhydrase inhibitors
Classification of Diuretics
A)Diuretics that inhibit transport in the Medullary Ascending Limb of the Loop of Henle(
Loop diuretics)
B)Diuretics that inhibit transport in the Distal Convoluted Tubule( Thiazides :
Indapamide , Metolazone)
C)Diuretics that inhibit transport in the Cortical Collecting Tubule (Potassium sparing
diuretics)
D)Diuretics that inhibit transport in the Proximal Convoluted Tubule ( Osmotic diuretics,
Carbonic Anhydrase Inhibitors)

5. Loop Diuretics

6. Loop Diuretics-Mode of action

7. Loop diuretic (Furosemide) has p.o. bioavailability 65% and t1/2
30–60 min. It acts on the ascending limb of Henley's loop by
increasing urine excretion of Na+, Cl, Mg2+ and Ca2+. Its diuretic
effect is achieved in 20–30 min after p.o. administration and lasts
4–6 h. Its effect after i.v. administration begins in 3–5 min and
lasts 2 h. In low doses (5 to 10 mg p.o.) furosemide has
antihypertensive effect.
Induce renal synthesis of prostaglandin
-increase in renal blood flow.
-redistribution of renal cortical blood flow.
It has a quick onset, shorter duration of action.

8. Furosemide – indications:
-Pulp edema (Acute LVF)
-Acute ischemic renal failure
-Anuria and eclampsia
-Forced diuresis in acute intoxications
-Hypertension
-Resistant cardiac failure.
Furosemide enhances the action of antihypertensive drugs and non-depolarazing
neuromuscular blockers.
Most common side effects
-Hypokalemia
-Hyperglycemia & hyperuricemia
-Transient damage to CN VII (esp. with Gentamycin).

9. Salidiuretics
(Thiazides and their analogues)
5–10%
Hydrochlorothiazide
Chlorthalidone
Indapamide
Indapamide SR
(does not have metabolic effects)
cardioprotector
nephroprotector

10. Salidiuretics mode of action

11. Thiazides increase equivalently Na+ and Cl- excretion (1:1)
in distal renal tubules and this increases diuresis. They lead to
excretion of 5 to 10% from filtrated Na+ ions and have moderate
diuretic action. They can be classified as sulfonamides with free
–NH2 group, without antimicrobial activity.
Maximum effect is produced in small doses.
Duration of action 12 -18 hours.

12. Common use of Thiazide diuretics are
-Hypertension 75 %
-Heart Failure 15 %
-Cerebral Edema 5 %
-Renal Failure 5%
Thiazides have a weak antihypertensive effect because they
reduce arterial wall sensitivity to NA (noradrenaline) and AT
(Angiotensin).
Decreases systolic BP by 10-15 mmHg
Decreases diastolic BP by 5-10 mmHg
They potentiate significantly the effect of other antihypertensive
drugs.
Thiazides increase plasma renin levels.Reduction of plasma
Sodium and osmolarity leads to “paradoxal” antidiuretic effect in
diabetes insipidus.

13. NICE 2011 GUIDELINES FOR TREATMENT OF
HYPERTENTION
Aged under 55 yrs Aged over 55 yrs or people of african/carribean origin
Step 1 A C
Step 2 A+C
Step 3 A+C+D
Step 4 Resistant hypertension
A+C+D consider further diuretic or Alpha Blocker or Beta Blocker
Key
A-ACE inhibitor or Angiotensin II receptor blocker (ARB)
C-Calcium channel blocker (CCB)
D-Thiazide – like Diuretics

14. Most common Side Effects of Thiazides
 Hypokalemia
-Particular caution when use with Digoxin
 Increase uric acid levels
 Impaired glucose tolerance
 Increase cholesterol levels

15. Potassium-sparing Diuretics
Amiloride
Triamterene
Spironolactone
3%
They have weak
diuretic action
and save K+.
Often they are used
in combination with
diuretics, causing
hypokalemia.

16. Potassium-sparing Diuretics
mode of action

17. Spironolactone (AldactoneR)is a steroid compound, which is a
competitive aldosterone antagonist.
It increases Na+ excretion and decreases K+ and urea excretion.
Its diuretic action is weak and is achieved slowly.
Spironolactone is effective in oedemas, caused by increased
production of aldosterone ascites in liver cirrhosis and
oedemas in congestive heart failure.
Spironolactone in low doses (25 mg/24 h) potentiates the
effect of ACE inhibitors. It saves K+ and Mg2+ ions and has
antiarrhyth-mic effect. It also prevents the development of
myocardial fibrosis, caused by aldosterone and in this way
contributes to enhancing myocardial contractility.