Comparison of the efficacy of the fixed-combination timolol/dorzolamide versus concomitant administration of timolol and dorzolamide.

The purpose of this study was to compare the efficacy of the fixed-combination solution of timolol 0.5%/dorzolamide 2% with the concomitant administration of its components, timolol 0.5% twice a day and dorzolamide 2% twice a day. Ninety-eight patients adequately controlled with a concomitant regimen of timolol and dorzolamide were switched to the fixed-combination regimen of the same components. Intraocular pressures at baseline and 4 weeks after the change in regimen were recorded. The mean baseline intraocular pressure (IOP) was 16.0 +/- 5.6 mmHg. Four weeks after the change in medication to the fixed-combination regimen, the mean IOP was 14.5 +/- 5.6 mmHg. The mean IOP change from baseline was -1.5 +/- 3.9 mmHg. The difference between the two treatment modalities was found to be statistically significant (p-value < 0.001). Eighty-one (83%) patients were considered successfully switched after 4 weeks of fixed-combination therapy, and seventeen eyes (17%) were deemed unsuccessful because a rise in IOP was detected. In conclusion, the fixed combination of timolol 0.5%/dorzolamide 2% twice a day provided equivalent or better intraocular pressure reduction in most patients who were successfully controlled on concomitant administration of its components, timolol and dorzolamide.