Acetazolamide is:

It is a sulfonamide derivative which noncompetitively but reversibly inhibits carbonic anhydrase in PT cells resulting in slowing of hydration of Carbon dioxide and leads to prompt but mild alkaline diuresis. The extrarenal actions of acetazolamide are: i) Lowering of intraocular tension due to decreased formation of aqueous humor (it is rich in HC03). ii) Decreased gastric HCl and pancreatic NaHC03 secretion: This action requires very high doses-clinically not significant. iii) Raised level of C02 in the brain and lowering of pH - sedation and elevation of seizure threshold. iv) Alteration of C02 transpo in lungs and tissues: these actions are masked by compensatory mechanisms. REF-Essentials of Medical Pharmacology, K.D Tripathi,6 th edition, page 569