Carbonic anhydrase inhibitors (amboss and UW)

Question 1

Carbonic anhydrase inhibitors agent?

Answer 1

acetazolamide

Question 2

what equation catazyles CA?

Answer 2

Enzyme that catalyzes the reaction CO2 + H2O ⇄ HCO3- + H+

Question 3

CA effect in kidney?

Answer 3

Kidney (in the proximal convoluted tubule): → ↑ H+ reabsorption and inhibition of Na+/H+ exchange → ↑ NaHCO3 diuresis and ↑ HCO3- elimination → compensatory hyperventilation!!!; disinhibition of central chemoreceptors → ↑ oxygenation

Question 4

CA effect in brain?

Answer 4

↓ CSF production

Question 5

CA effect in acid-base effect?

Answer 5

alkalinizes urine and acidifies blood

Question 6

Indications of acetazolamide?

Answer 6

Acute glaucoma (open angle and angle-closure glacuoma)
Altitude sickness (counteracts respiratory alkalosis)
Idiopathic intracranial hypertension!!!
Metabolic alkalosis!!! (because leads to metabolic acidosis)
Prevention of cystine kidney stones

Question 7

Why acetazolamide prevents cystine kidney stones?

Answer 7

Cystine kidney stones form in acidic urine; therefore urine alkalization prevents their formation.

Question 8

Generally what reaction is catalyzed by CA?

Answer 8

catalyzation of reactions needed for NaHCO3 reabsorption.

Question 9

When CA inhibits reaction, what effect on HCO3?

Answer 9

Blocks HCO3 reabsorption in the proximal tubule.

Question 10

What happens with urine when reabsorption of HCO3 due to CAI?

Answer 10

Enhanced HCO3 and water excretion AS WELL AS increased urine pH and potential metabolic acidosis

Question 11

Urine pH due to CAI?

Answer 11

increased pH

Question 12

What blood pH due to CAI?

Answer 12

Metabolic acidosis

Question 13

in what tissues are CA according to uw?

Answer 13

eyes, pancreas, GI, CNS, RBC

Question 14

CA effect in eyes?

Answer 14

modulated HCO3 formation in aqueous humor. Inhibition of HCO3 formation –> ↓ production of aqueous humor

Question 15

What effect of acetazolamide on HCO3 stores in body?

Answer 15

decrease total blood stores

Question 16

Side effects of acetazolamide?

Answer 16

Hyperammonemia with paresthesias (aka NH3 toxicity - can also lead to nausea, hyperventilation, altered mental status, and seizures)

Proximal renal tubular acidosis → hyperchloremic, nonanion gap metabolic acidosis

Hypokalemia

Sulfonamide hypersensitivity (SULFA ALERGY)!!

Calcium phosphate stone formation (alkaline urine promotes precipitation - insoluble at high pH)

Neuropathy

Question 17

What from complications are rare?

Answer 17

metabolic acidosis, dehydratation, hypokalemia, hyponatremia

Question 18

What from complications are common?

Answer 18

somnolence, paresthesias, urine alkalinization

Question 19

Acetazolamide. Body electrolyte level. Na?

Answer 19

decreased

Question 20

Acetazolamide. Body electrolyte level. K?

Answer 20

decreased

Question 21

Acetazolamide. Body electrolyte level. HCO3?

Answer 21

decreased

Question 22

Acetazolamide. Body electrolyte level. Ca2?

Answer 22

no change

Question 23

Acetazolamide. Body electrolyte level. Uric acid?

Answer 23

no change

Question 24

Metabolic alkalosis effect on ventilation?

Answer 24

Metabolic alkalosis stimulates compensatory HYPOventilation that may hinder weaning from mechanical ventilation in critically ill patients.

Question 25

effect of metabolic acidosis from acetazolamide on metabolic alcalosis?

Answer 25

generated acidosis reduced blood alkalinity to help normalize pH.

Question 26

Why CAI has low diuretic effect?

Answer 26

because most of the Na blocked from reabsorption in the PCT is REABSORBED MORE DISTALLY.

Question 27

What medication cause metabolic alkalosis? what role of acetazolamide?

Answer 27

metabolic alkalosis caused by loop diuretics and thiazides.

So CAI can be use to help to offset this metabolic alkalosis.

Question 28

Contraindications of acetazolamide?

Answer 28

Hyperchloremic metabolic acidosis

Severe renal insufficiency

Adrenocortical insufficiency

Hyponatremia, hypokalemia

Hepatic disease or insufficiency

Long-term use in glaucoma

Question 29

Why do not prescribe acetazolamide in liver disease?

Answer 29

CAI decrease the renal ammonia clearance. There is some evidence that acetazolamide can lead to idiosyncratic liver injury.