A repeated dose-response study of methazolamide in glaucoma

K. Dahlen, D. L. Epstein, W. M. Grant, B. T. Hutchinson, E. L. Prien Jr and J. M. Krall

Twenty-two patients with open-angle glaucoma were given weekly courses of methazolamide at different dosages. Mean intraocular pressure reductions of 3.3, 4.3, and 5.6 mm Hg were achieved at dosages of 25 mg, 50 mg, and 100 mg of methazolamide every eight hours, respectively. Maximal intraocular pressure lowering was still present nine to ten hours after administration. The mean reduction in outflow pressure for all eyes receiving a daily dosage of 300 mg was only 31%, but this included eyes (17% of the total) that demonstrated less than 13% reduction in outflow pressure, despite similar methazolamide serum levels. Eight patients subsequently received acetazolamide, 250 mg four times a day for a week. The effect of this dosage of acetazolamide on pressure was between the effects of 50 and 100 mg of methazolamide three times daily.