Systemic carbonic anhydrase inhibitors
Carbonic anhydrase inhibitors are sulfonamide drugs, which act on the ciliary epithelium, on -carbonic anhydrase isoenzyme II catalyses conversion of CO2 and H2O to HCO3 and H+, a process important for the production of aqueous humor.
Acetazolamide and methazolamide are able to reduce IOP, when taken orally, by decreasing aqueous production. Acetazolamide tablets (125 mg and 250 mg) and methazolamide tablets (25 and 50 mg) are available in the market. Acetazolamide is administered four times daily and methazolamide two or three times daily. Both medications cause several side effects, including paresthesia of fingertips and toes, fatigue, depression, kidney stones, thrombocytopenia, agranulocystosis, and aplastic anemia.[36]