A short review by Dr. SWETHA RANI AITHA YOUTUBE LINK FOR AUDIO AND VIDEO-https://youtu.be/FwdDjKhXWVo

1. CARBONIC ANHYDRASE
INHIBITORS(DIURETICS)

2. • This enzyme is present
in kidneys and also in
various other tissues
such as CNS, eyes,
gastric mucosa,
pancreas, RBCs.
Carbonic
Anhydrase enzyme
INTRODUCTION
• There are many types of Carbonic Anhydrase Enzymes

3. • Carbonic Anhydrase Inhibitors are a group of
diuretics that act on S2segment of PCT by
inhibiting the enzyme Carbonic Anhydrase
• Type IV CA enzyme is present on luminal / basolateral membrane and Type II
in cytoplasm of epithelial cells of PCT .
• In the Kidneys there are two types of CA enzymes.
• They are type II and type IV CA enzymes.
CARBONIC ANHYDRASE INHIBITORS

4. DRUGS:
 Acetazolamide
 Methazolamide
 Dichlorphenamide
 Dorzolamide
 Brinzolamide
 Zonisamide
 Ethoxzolamide
Diuretic action is produced by
Acetazolamide, when administered orally at
a dose of 250 mg, BD.

5. GLOMERULUS
Basolateral
membrane
Luminal
membrane
Na+
Na+
H+
Na-H+
antiport
HCO3
-
H2CO3
CO2
H2O
H2O
CO2
H2CO3
CA
IV
CA
II
Na+-HCO3
-
symport
Na+
HCO3
- HCO3
-
NaHCO3
BLOOD
MECHANISM OF ACTION
EXCRETION OF WATER, HCO3
-,Na+, K+
PCT
H+
HCO3
-

6. PHARMACOKINETICS
• Absorbed orally
• Highly distributed to tissues containing CA
• Not metabolized but actively secreted in PCT

7. Effect on Kidney-
• Inhibition of NaHCO3 reabsorption in the PCT and inhibition of secretion of
acids in the collecting duct.
PHARMACODYNAMICS
Hemodynamic effect-
• Decrease in RBF and GFR due to increased afferent arteriolar resistance
triggered by tubulo-glomerular feedback.
Effect on electrolyte excretion in urine-
• Increase in urinary excretion of Bicarbonates, Sodium, Potassium

8. CLINICAL USES
Urinary Alkalinization
ACE t A z O l AMIDES
Heart Failure
Glaucoma (eye) Oedema
Acute mountain sickness
(high altitude sickness)
Idiopathic intracranial
Hypertension
Diuresis
Metabolic
alkalosis
Petit mal epilepsy
Uric acid and cystine
stones
Other conditions like
Hyperphosphatemia,
Familial periodic
paralysis

9. ADVERSE EFFECTS
Hypokalemia
Hyperchloremic metabolic acidosis
Hepatic encephalopathy
Stone formation(calcium oxalate)
Sulfonamide like effects
Fever
Sedation
Paresthesia
H
F
S
P

10. CONTRA INDICATIONS
A
S
H
Severe COPD.
Hyperchloremic Acidosis
Hepatic cirrhosis
DRUG INTERACTIONS
M
O
Action of Methenamine is blocked by CAIs
CAIs reduce excretion of weak Organic acids