Success rates for switching to dorzolamide/timolol fixed combination in timolol responders who are insufficiently controlled by latanoprost monotherapy.

Purpose: We aimed to investigate the safety and efficacy of dorzolamide/timolol fixed combination (DTFC) in timolol responders with ocular hypertension or open-angle glaucoma who switched to DTFC because of insufficient control on latanoprost.

Methods: We carried out a prospective, open-label cohort study with an active-historical control in which qualifying patients must have been treated with latanoprost monotherapy for at least 4 weeks, must have demonstrated insufficiently controlled intraocular pressure (IOP) (> or = 19 mmHg at 08.00 hours), and must have shown a decrease in IOP at 2 hours after timolol instillation of > or = 3 mmHg or > or = 15%. Patients then began DTFC dosed at 08.00 hours and 20.00 hours and discontinued latanoprost. Patients were evaluated again after 4 and 12 weeks.

Results: In 57 patients IOP was further reduced by 2.4 +/- 3.3 mmHg at 08.00 hours (p < 0.0001) and by 3.5 +/- 3.3 mmHg at 10.00 hours (p < 0.0001) after switching to DTFC. Responses to the Comparison of Ophthalmic Medications for Tolerability (COMTol) questionnaire showed no difference between DTFC and latanoprost for in terms of overall preference, typical daily activities, limitation of activities, compliance, satisfaction or quality of life (p > 0.05). However, greater frequency in burning and/or stinging (p < 0.0001) and bitter taste (p < 0.0001) were observed with DTFC, whereas unusual taste (p = 0.02) and itchy eyes (p = 0.05) were associated with latanoprost.

Conclusions: This study suggests that patients who are insufficiently controlled on latanoprost monotherapy, and who are timolol responders, can generally achieve further IOP reduction and similar tolerance levels when changed to DTFC.