Brief overview of Diuretics. Explained in simple language

2. ANTI-DIURETICS
BY:
DR. ELAF KHALID

3.  Drugs that promotes the excretion of the (Na+), (Cl- )
or (HCO3- ) and water resulting in increase in the
urine flow, change in urine pH and change the ionic
composition of the urine and blood.
INTRODUCTION
DIURETICS

4. Classification
DIURETICS
 Classification of Diuretics:
Thiazides Hydrochlorothiazide, Chlorthalidone,
Indapamide
Loop Diuretics Furosemide
K+ sparing Spironolactone, Triamterene, Amiloride
Carbonic Anhydrase Inhibitors Acetozolamide
Osmotic Diuretics Mannitol
ADH agonists Desmopressin
ADH antagonists: Conivaptan

5. Classification
DIURETICS
 Drugs that modify salt excretion:
 PCT: carbonic anhydrase inhibitors
 TAL: loop diuretics
 DCT: thiazides
 CCT; K-spairing diuretics
 Osmotic diuretics; manitol
 Drugs that modify water excretion
 Osmotic diuretics: manitol
 ADH agonists: desmopressin
 ADH antagonists: conivaptan, demeclocycline, lithium

6. Site of action
DIURETICS

7. Site of action
DIURETICS
DIURETICS Site of action Mechanism
Carbonic Anhydrase
Inhibitor (CA-I)
1. Proximal tubules Inhibition of bicarbonate
reabsorption
Loop Diuretic 1. Loop of Henle (thick
ascending limb)
Inhibition of Na+ , K+ , 2Cl
cotransport
Thiazide 1. Early distal tubule Inhibition of Na+ , Cl
cotransport
K+ sparing diuretics 1. Late distal tubule
Collecting duct
Inhibition of Na+
reabsorption and K+
secretion
Osmotic Diuretic 1. Proximal tubules
2. Collecting duct
Inhibition of water and
reabsorption

8. Carbonic Anhydrase
Inhibitor
DIURETICS
 Carbonic anhydrase catalyzes : CO2+H2O → H2CO3
 Inhibition of Bicarbonate (HCO3 - ) reabsorption
 Reduces Na+-H+ -exchange
 Indications:
 Glaucoma
 Prevent mountain sickness (high altitude)
 Urinary alkalinization

9.  Adverse effects:
 Metabolic acidosis
 Renal stones (Phosphate and Calcium stone)
 Renal potassium wasting; (NaHCO3 - ) enhances K+
Carbonic Anhydrase
Inhibitor
DIURETICS

10. Loop Diuretics
 Mechanism:
 Loop diuretics should be excreted into the lumen
 Inhibits Na+ , K+ , 2Cl- symporter→significantly increases the
excretion of Na+ , K+ , Cl-
 Osmotic gradient for water reabsorption is also decreased →
increasing water excretion
 Ca2+ and Mg2+ are excreted as well.
DIURETICS

11. Loop Diuretics
 Indications:
 Congestive heart failure (1st line drug)
 Acute pulmonary edema
 Edema due to renal failure, nephrotic syndrome, ascites
 Hypercalcemia (that induced by malignancy)
 Severe hypertension
DIURETICS

12. Loop Diuretics
 Adverse effects:
 Hypokalemic metabolic alkalosis
 Ototoxicity
 Typical sulfonamide allergy
 Hypovolemia
DIURETICS

13. DIURETICS
Thiazides
 Mechanism of Actions
 Thiazides are secreted by proximal tubules but works in DCT
–
 Inhibit Na+ -Cl- symporter from the lumen to tubular cells
 Increase Na+ , Cl- excretion (and water)

14. DIURETICS
Thiazides
 Effects on Electrolytes:
 Increases Na+ and Cl- excretion
 Hypokalemic metabolic alkalosis
 Inhibits uric acid secretion
 Decreases Ca2+ excretion
 Increases Mg2+ excretion

15. DIURETICS
Thiazides
 Indications of Thiazides:
 Hypertension (single drug or in combination)
 Chronic, mild- heart failure
 Edema (loop diuretic is preferable)
 Nephrogenic Diabetes insipidus
 Prevention of Ca++ excretion in osteoporosis and calcium
nephrolithiasis

16. DIURETICS
Thiazides
 Adverse effects:
 Hypo K+
 Hypo Na+,
 Hypo Mg++
 Hyperuricemia Hyperglycemia and hypercholesterolemia)
 Hypercalcemia
 Sexual dysfunction

17.  Amiloride, triamterene
 Inhibit Na+ reabsorption
 Reduced K+ secretion
 Aldosterone antagonist (Spironolactone, eplerenone)
 Aldosterone induces the expression of Na/KATPase and Na+
channel
 Spironolactone and eplerenone blocks aldosterone receptor
resulting in reduce Na+ reabsorption and K+ secretion
Potassium Sparing
Diuretics
DIURETICS

18.  INDICATIONS:
 To prevent hypokalemia
 Aldosteronism (that occur in cirrhosis)
 Adverse Effects:
 Spironolactone → Hyperkalemia
 Antiandrogenic effect » gynecomastia, » decrease of libido, impotence, »
menstrual disturbance.
 Megaloblastic anemia: Triamterene (folate antagonist)
Potassium Sparing
Diuretics
DIURETICS

19.  Mannitol (prototype)
 Others rarely used: urea, glycerin, isosorbide
 MOA:
 OD is filtrated and increases osmotic pressure in tubular lumen
 Hence, increases excretion of water and electrolytes, ↑ volume of urine &
rate of urine flow through the tubule
 Mannitol can also reduce brain volume and intracranial pressure by
osmotically extracting water from the tissue into the blood
 A similar effect occurs in the eye
Osmotic Diuretics
DIURETICS

20.  Indications:
 Glaucoma (rare) ↓ IOP
 Brain edema ↓ brain volume & pressure
 Disequilibrium syndrome after hemodialysis • Solute overload in sever
hemolysis and rhabdomyolysis
 Adverse Effects
 Removal of water from the I.C compartments → initial increase of plasma
volume → Hypo Na+ → headache, nausea, vomiting
 Water exc → Hypovolemia → hypernatremia
 Hypersensitivity reaction
Osmotic Diuretics
DIURETICS

21.  Indications: (Agonists)
 ADH and desmopressin reduce urine volume and concentrate it, are
in Pitutary Diabetes Insipidus
 Indications: (Antagonist)
 Oppose the actions of ADH
 Act on the same V2 receptors.
 Syndrome of inappropriate ADH secretion (SIADH) can be treated with
demeclocycline and conivaptan
(ADH) Agonists and
Antagonists
DIURETICS

22.  Adverse effects (Agonists):
 ADH, Desmopressin, water overload, hyponatremia
 Adverse effects (Antagonists):
 Demeclocycline: bone and teeth abnormalities
 Infusion site reation
 Demyelination
(ADH) Agonists and
Antagonists
DIURETICS

23. THANKS