Carbonic anhydrase inhibitors act on the kidney by inhibiting the carbonic anhydrase enzyme in the proximal convoluted tubules, preventing the reabsorption of bicarbonate ions. This leads to increased bicarbonate excretion, sodium excretion, water loss, and metabolic acidosis. They are used to treat glaucoma by decreasing aqueous humor production and lowering intraocular pressure, as well as acute mountain sickness and edema. Common side effects include acidosis, hypokalemia, and drowsiness.

1. Presented by Group 4
Drugs That Act on the
Kidney
_Anum Sajid…

2. Introduction
 Drugs that act on the kidney have important
applications in renal, cardiovascular, and
endocrine disorders. These disorders mainly
involve sodium and water homeostasis.

4. 

5. CARBONIC
ANHYDRASE
INHIBITORS

6. Carbonic
Anhydrase
• Carbonic anhydrase enzymes are found in the:
• Proximal convoluted tubules (PCTs) of
the kidneys: involved in HCO3
– reabsorption
• Eyes: involved in aqueous humor production
• Glial cells in the brain: involved in CSF
production

7.  In PCT carbonic anhydrase catalyze:
Dehydration of H2CO3 to CO2 at the
luminal membrane.
Rehydration of CO2 to H2CO3 in the
cytoplasm.

8. Carbonic
Anhydrase
Inhibitor
 It is Sulphonamide derivative.
 Duration of action: 8-12hrs
 Well absorbed orally.
 Include:
Acetazolamide
Methazolamide
 Dorzolamide

9. Pharmacokinetics
Acetazolamide
• Readily absorbed
• Half-life: 2.5‒9 hours
• Not metabolized
Methazolamide
• Relatively
slower absorption
• Half-life: 14 hours
• Metabolizes slowly
within the GI tract

10. Mechanism of
Action
 Non-competitively and reversible inhibit
Carbonic Anhydrase in Proximal tube;
 Block resorption of bicarbonate ions; preventing
Na/H exchange.

11. • Inhibition of carbonic anhydrase:
• Keeps HCO3
– in the renal tubules.
• Prevents secretion of HCO3
– into the
aqueous humor in the eyes.
• Prevents secretion of HCO3
– into the CSF in
the brain.

12. 

13. Physiologic
effects
of CAIs
 Use of CAI’s results in:
• ↑ HCO3
– excretion leading to metabolic
acidosis.
• ↑ Na+ excretion → water follows Na+ →
diuresis.
• ↓ Intraocular pressure (IOP) due to ↓
aqueous humor production
• ↓ Intracranial pressure (ICP) due to ↓ CSF
production

14. Therapeutic
Uses
 Glaucoma—Dec. formation of
aqueous humor thereby lowering
the intraocular pressure.
 Prophylaxis and treatment of acute
Mountain sickness.
 To Alkalinize urine for UTIs.
 Periodic Paralysis
 Edema

15. Adverse
Reactions
 Acidosis
 Hypokalemia
 Drowsiness, paresthesia
 Abdominal discomfort,
 Hypersensitivity reactions.
 Bone marrow depression.
 Interfere with elimination of NH3 in urine.
 CONTRAINDICATED in Liver disease.

16. The End