Additive effect of dorzolamide or carteolol to latanoprost in primary open-angle glaucoma: a prospective randomized crossover trial.

PURPOSE

To compare the additive effect of dorzolamide or carteolol to latanoprost on intraocular pressure (IOP) in glaucoma patients.

DESIGN

Prospective open-label randomized crossover clinical study.

METHODS

A total of 64 patients with primary open-angle glaucoma were treated with latanoprost 0.005% once daily for 3 months then randomized to receive latanoprost plus dorzolamide 1% 3 times daily (dorzolamide preceding group; n=32) or carteolol hydrochloride 2% twice daily (carteolol preceding group; n=32) for a further 3 months. Then, all patients were crossed over to the opposite treatment arm for a further 3 months. IOP was recorded each month at around the time same as on the baseline day.

RESULTS

Sixty-one patients (95%) completed this trial. In the dorzolamide preceding group, mean (+/-SD) IOP was 19.0+/-2.1 mm Hg at baseline and 16.0+/-2.1 mm Hg at the end of latanoprost monotherapy (P<0.01). Addition of dorzolamide reduced IOP to 15.0+/-1.3 mm Hg and this was not changed by switching to carteolol (15.1+/-1.7 mm Hg). In the carteolol preceding group, IOP was 19.1+/-1.9 mm Hg at baseline and 16.2+/-1.2 mm Hg at the end of latanoprost monotherapy (P<0.01). Addition of carteolol reduced IOP to 14.9+/-1.5 mm Hg, and after switching to dorzolamide IOP was 15.2+/-1.5 mm Hg. Mean additional IOP reduction was 0.9+/-1.2 mm Hg (5.6%) for the latanoprost-dorzolamide combination and 1.1+/-1.5 mm Hg (6.8%) for the latanoprost-carteolol combination. Hence, IOP reduction by carteolol and dorzolamide additionally to latanoprost was not different.

CONCLUSIONS

Both dorzolamide and carteolol reduce IOP additively when used in combination with latanoprost, and the additive effect of these drugs is equal.