Carbonic anhydrase inhibitors reduce the activity of carbonic anhydrase, an enzyme responsible for catalyzing the reaction between carbon dioxide and water into carbonic acid and then bicarbonate. This reduces the resorption of bicarbonate from the proximal tubule in the kidneys, which causes a direct increase in bicarbonate excretion and mild increases in sodium, and potassium excretion. Generally, the electrolyte effects of carbonic anhydrase inhibitors are mild and they are typically not used for their diuretic capacity. Acetazolamide, dichlorphenamide, and methazolamide are carbonic anhydrase inhibitors.
Carbonic anhydrase inhibitors also decrease the secretion of aqueous humor (the aqueous humor is the clear fluid that fills the space between the lens and the cornea of the eyeball), which results in a decrease in intraocular pressure.
Carbonic anhydrase inhibitors are mainly used for the treatment of glaucoma or other ocular conditions where lowering of the intraocular blood pressure has been deemed beneficial. Acetazolamide is also used for the treatment and prevention of acute mountain sickness (also known as altitude sickness) and in some types of epilepsy. Dichlorphenamide may be used to treat certain inherited muscle disorders. Carbonic anhydrase inhibitors may be also used in the treatment of other conditions.
