Which carbonic anhydrase inhibitor is administered orally?

Acetazolamide is the carbonic anhydrase inhibitor that is administered orally. It is commonly used for the treatment of various conditions such as glaucoma, edema due to heart failure, and to reduce intracranial pressure in cases of altitude sickness.

The oral administration of acetazolamide allows for systemic effects, making it effective in managing these conditions. It works by inhibiting the enzyme carbonic anhydrase, which plays a critical role in the reabsorption of bicarbonate and subsequently affects fluid balance and acid-base homeostasis in the body.

In contrast, brinzolamide and dorzolamide are primarily formulated for topical administration in the eye, mainly as eye drops for the treatment of elevated intraocular pressure in glaucoma. Timolol is a non-selective beta-blocker that is also used topically in ophthalmic formulations, not orally. Thus, the choice of acetazolamide aligns with the requirement for an oral carbonic anhydrase inhibitor.