A randomized trial in patients inadequately controlled with timolol alone comparing the dorzolamide-timolol combination to monotherapy with timolol or dorzolamide. Dorzolamide-Timolol Combination Study Group.

OBJECTIVE

To compare the dorzolamide-timolol fixed combination twice daily to its components, timolol maleate and dorzolamide hydrochloride, given in their usual monotherapy regimens in patients whose intraocular pressure (IOP) was not controlled on timolol twice daily alone.

DESIGN

Parallel, randomized, double-masked, and active-controlled study.

PARTICIPANTS

Enrolled were 253 patients from 22 sites throughout the United States.

INTERVENTION

After a 3-week run-in of timolol (TIMOPTIC; Merck & Co., Inc., Whitehouse Station, NJ) twice daily, eligible patients received either the combination (COSOPT; Merck & Co., Inc., Whitehouse Station, NJ) twice daily (plus placebo to ensure masking), timolol twice daily (plus placebo to ensure masking), or dorzolamide (TRUSOPT; Merck & Co. Inc., Whitehouse Station, NJ) three times daily for 3 months.

MAIN OUTCOME MEASURES

Intraocular pressure taken at hours 0 (trough) and 2 (peak) after week 2 and months 1, 2, and 3 was compared to baseline within each treatment group and between the combination and each component group. The safety profile of the combination was compared to each component.

RESULTS

The combination was numerically superior at all study timepoints and was statistically superior at all timepoints except for month 2, hour 0 for timolol, and month 2, hour 2 for dorzolamide. The safety profile of the combination reflected those of its two components. The number of patients reporting ocular or local adverse experiences was greater for the combination (45%) and dorzolamide (45%) than for timolol (27%), with burning and/or stinging eye being the most frequently reported.

CONCLUSION

The dorzolamide-timolol combination provides additional IOP lowering compared to either of its individual components and generally is well-tolerated.