Short-term dose response characteristics of acetazolamide in man

Nine patients with ocular hypertension each randomly received on separate days 0, 63, 125, 250, and 500 mg of acetazolamide (Diamox). In a double masked manner, acetazolamide plasma levels and intraocular pressure were monitored for seven hours following administration. Plasma levels increased linearly with dose, reaching 30 microgram/ml with the 500-mg dose. Maximum plasma levels occurred at one hour, and the minimum IOP was at two hours. The maximum IOP effect was a 30% to 35% fall. The IOP response was related to dose and plasma level, up to a 63-mg dose, which produced an average fall of 8.2 mm Hg. Little further average effect was documented at higher doses or plasma levels. The duration of response was slightly prolonged by 250 mg, but 500 mg showed no greater response. Thus, a 63-mg dose or a plasma level of 4 to 5 microgram/ml was as effective in lowering IOP as higher doses that produced plasma levels of 10 microgram/ml or more.