Fixed-dose combination of drugs effectively lowers IOP

By Joanna Lyford, Senior medwireNews Reporter

A fixed-dose combination of brinzolamide and brimonidine is more effective than either drug given alone for lowering intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension, results of a phase III trial indicate.

Furthermore, the superior efficacy was achieved without an increase in side effects, say Gregory Katz (Huron Ophthalmology, Ypsilanti, Michigan) and co-authors writing in JAMA Ophthalmology.

The trial involved 660 adults with glaucoma who were randomly assigned to one of three treatments: fixed-combination brinzolamide 1% and brimonidine 0.2%; brinzolamide 1%; or brimonidine 0.2%. All treatments were administered topically three times daily.

The study's primary endpoint was mean IOP measured four times during the course of 1 day at the end of 3 months of treatment.

At baseline, IOP was comparable among the three treatment groups. At 3 months, however, mean IOP was significantly lower in the brinzolamide-brimonidine group (16.3-19.8 mmHg across the four time points) than in either the brinzolamide group (19.3-20.9 mmHg) or the brimonidine group (17.9-22.5 mmHg).

Patients in the brinzolamide-brimonidine group also demonstrated the largest percentage reduction in IOP between baseline and 3 months, with reductions ranging from 24.1% to 34.9% across time points. In the brinzolamide group the reductions ranged from 16.9% to 22.6% while in the brimonidine group the reductions ranged from 14.3% to 25.8%.

There were 10 serious adverse events, just one of which (chest pain in a patient taking brinzolamide) was considered to be treatment-related. In all, 129 patients experienced at least one treatment-related adverse event, mostly ocular events. The frequency of these was comparable among the three treatment groups.

Analysis of secondary endpoints found no other significant differences among the groups with regard to number of letters read, ocular signs, cup-disc ratio, corneal thickness, and retinal ganglion sensitivity or loss.

However, patients taking the brinzolamide-brimonidine combination showed a slight trend toward a decrease in systolic and diastolic mean blood pressure between baseline and 3-month follow up at the 10-am time point.

Katz et al conclude: "The significantly lower mean IOP of the brinzolamide-brimonidine group compared with that of either the brinzolamide group or the brimonidine group at all four time points supports the hypothesis that the IOP-lowering contribution of the combination therapy is greater than the contribution of either of its components and demonstrates that this effect occurs early and is maintained through 3 months of treatment."

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