What is the dosing of oral CAIs?

• A. BID
• B. QD-QID
• C. TID
• D. QOD

Answer: (B)

Oral carbonic anhydrase inhibitors lower intraocular pressure by reducing aqueous humor production through inhibition of carbonic anhydrase in the ciliary body. Because their effect wanes with time, they’re given in small, frequent doses to maintain IOP control. A typical regimen is 250 mg every 6 hours, totaling up to about 1000 mg per day, though in practice the dose can be adjusted to as little as once daily or as often as four times daily depending on response and tolerability. That broad dosing window—once daily to four times daily—best reflects how clinicians manage oral CAIs. The other schedules are less representative of standard practice because these meds generally require multiple daily doses to sustain effect, and dosing every other day would not reliably control IOP.