acetazolamide, methazolamide, dorzolamide, brinzolamide
- weak diuretic: carbonic anhydrase inhibitor
- Used primarily for glaucoma: blocks CA in ciliary cells to prevent HCO3- secretion into aqueous humor...and reduce Na and H2O transport --> decrease IOP)
- Also may be used for acute mountain sickness and epilepsy.
- Very weak diuretic; CA is in luminal membrane of proximal tubule, so by blocking CA, deplete intracellular H+ and Na/H+ exchanger is inhibited so Na+ stays in lumen.
- but 99% of CA must be inhibited before diuretic activity expressed. Even if it is blocked, not much effect because thick ascending limb can compensate for the less effective proximal reabsorption.