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Carbonic Anhydrase Inhibitors (CAIs) Cheat Sheet by

Carbonic Anhydrase Inhibitors (CAIs) - diuretics


- inhibit activity of enzyme carbonic anhydrase (found in kidneys, eyes, and other parts of body)
- work at the location of the carbon anhydrase enzyme system along nephron (primarily proximal tubule
- Medica­tions: Acetaz­olamide


- treatment of glaucoma
- edema
- high-a­ltitude sickness symptoms (headache, nausea, shortness of breath, dizziness, drowsi­ness, fatigue)
- adjunct drugs in long-term management of open-angle glaucoma
- short term in conjun­ction with miotics to lower intrao­cular pressure in prepar­ation for ocular surgery
- adjunct in treatment of secondary glaucoma
- manage edema secondary to heart failure that has become resistant to other diuretics


- digoxin: hypoka­lemia, toxicity
- cortic­ost­eroids: hypoka­lemia
- amphet­amines, carbam­aze­pine, cyclos­porine, phenytoin, and quinidine: effects may be increased

Mechanism of Action and Drug Effects

- increase sodium excretion by decreasing sodium­-hy­drogen ion exchange throughout the renal tubule
- can induce respir­atory and metabolic acidosis --> increase oxygen­ation by increasing ventil­ation
- also decrease secretion of aqueous humor in the eye and thus decrease intrao­cular pressure
- elevation of blood glucose level and glycosuria in diabetic patients
- reduce formation of hydrogen and bicarb­onate ions from carbon dioxide and water through inhibition of carbonic anhydrase activity - results in availa­bility of ions (hydrogen)


- drug allergy
- severe renal or hepatic dysfun­ction
- hypona­tremia
- adrenal gland insuff­iciency
- hypoka­lemia
- cirrhosis

Adverse Effects

- metabolic abnorm­alities (ex: acidosis and hypoka­lemia)
- drowsiness
- anorexia
- parest­hesias
- hematuria
- urticaria
- photos­ens­itivity
- melena (blood in stool)


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