2. DEFINITION
:-
► Diuretics are chemicals that increase the rate of urine
formation. By increasing the urine flow rate in kidney,
diuretic usage leads to the increased excretion of
electrolytes (especially sodium
and chloride ion) and water from the body.
3. PHARMACOLOGICAL CLASSIFICATION
A. Loop diuretics
B. Thiazides
C. Carbonic anhydrase inhibitor
D. Potassium sparing diuretics
1. Aldosterone antagonists
2. Epithelial sodium channel blocker
E. Osmotic diuretics
5. Loop diuretics (Inhibitors of Na+-K+-2Cl- co-transport):-
► Mechanism of action:
❑ Loop diuretics inhibit the body's ability to reabsorb sodium
at the ascending loop in the kidney which leads to a retention of
water in the urine.
❑ No transport systems in descending loop of henle.
❑ Inhibits Na-K-2Cl transporter in thick ascending loop of henle.
❑ Competes with Cl- binding site
► Use : a. edema: cardiac, pulmonary or renal
b. hypertension
► Example of loop diuretics include Furosemide,Bumetanide,Ethacrynic acid and Torsemide
6. B. Thiazides:-
► Mechanism of action :
❑ active in distal convoluted tubule.
❑ inhibit Na+ and Cl- transporter in
distal convoluted tubules.
❑ increased Na+ and Cl- excretion.
❑ weak inhibitors of carbonic anhydrase.
► Use : a.hypertension
b. congestive heart failure
► Example of thiazides include Cholorthalidone, Hydroclorothiazide, Metolazone
7. C. Carbonic anhydrase inhibitor:-
► Mechanism of action :
❑ Inhibits carbonic anhydrase in renal proximal tubule cells.
❑ Carbonic anhydrase catalyzes formation of HCO3- and H+
from H2O and CO2.This formation is inhibited by
CA inhibitors.
❑ Suppress CO2 reabsorption from glomerular filtrate.
❑ Na+ - HCO3
- excretion is increased.
► Use : a. CA inhibitors reduce intraocular
pressure in glaucoma by decreasing production
of aqueous humor.
b. acute mountain sickness.
► Example of carbonic anhydrase inhibitor include Acetazolamide
8. D. Potassium sparing diuretics :-
►Mechanism of action :
❑ K+ sparing diuretics function in CCD
❑ Do not promote the secretion of potassium
into the urine.
❑ decrease Na+ transport in collecting tubule.
⮚ Aldosterone antagonists
⮚ Epithelial sodium channel blockers
►Use : a. primary hyperaldosteronism
b. cirrhosis
► Example of potassium sparing diuretics include Spironolactone , Triamterene,
Amiloride.
9. E. . Osmotic diuretics :-
► Mechanism of action :
❑ osmotic diuretics are not reabsorbed.
❑ increases osmotic pressure specifically in the
proximal tubule and loop of Henle.
❑ prevents passive reabsorption of H2O.
❑ increased Na+ excretion.
► Use : a. drug of choice: non-toxic, freely filtered,
non-reabsorbable .
b. administered prophylactically for CVS disease,
surgery.
► Example of osmotic diuretics include Manitol, Urea,
Glycerol.
10. THERAPEUTIC USES
❖In medicine,diuretics are usedto treat chronic
heart failure.
❖Liver cirrhosis
❖ Hypertension
❖ Water poisoning
❖ Certain kidney diseases.
❖ Pregnancy associated edema.
❖ Nephrotic syndrome.
