carbonic anhydrase inhibitor

Carbonic anhydrase inhibitors work by blocking carbonic anhydrase, an enzyme that catalyzes the reversible reaction CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-. In the kidney, this inhibition occurs primarily in the proximal tubule, preventing reabsorption of filtered bicarbonate and causing mild diuresis with loss of Na+, K+, and HCO3-. The resulting metabolic acidosis limits their use as diuretics. In the eye, these drugs reduce aqueous humor production by inhibiting carbonic anhydrase in ciliary processes, lowering intraocular pressure in glaucoma. They also work in the brain to reduce CSF production and have anticonvulsant effects through pH changes that affect neuronal excitability. At high altitudes, they help prevent altitude sickness by causing metabolic acidosis that stimulates breathing. Side effects include metabolic acidosis, hypokalemia, kidney stones (due to alkaline urine), paresthesias, and taste alterations. Contraindications include severe kidney or liver disease.