[Stereospecificity of lowering intraocular pressure using a locally administered carbonic anhydrase inhibitor]

As MK-417, the S-enantiomer of the racemic compound MK-927, is the more active enantiomer in vitro, the potential differential ocular hypotensive activity was investigated in patients. The 1% concentration was chosen as the basis for comparison, as preliminary data indicated that the concentration would fall relatively steeply on the dose-response curve. This was a two-center crossover study of 1% MK-417, 1% MK-927, and placebo (common vehicle) in 27 patients with bilateral, relatively symmetric primary open-angle glaucoma or ocular hypertension. Following a washout period for ocular hypertensive therapy, IOP had to be greater than or equal to 23 mmHg at 10:00 o'clock with IOP difference between eyes less than or equal to 6 mmHg. Treatment days were separated by a 1-2 week washout period. IOP was measured at 9:30. At 10:00 patients received the test drug in one designated eye and placebo in the other eye. IOP was measured at 1, 2, 4, 6, and 8 h after the dose. IOP and the percentage of change in IOP from 30 min before the dose in the active drug-treated eye shows that MK-417 is slightly more potent than MK-927 in this patient model.