Latanoprost administered once daily caused a maintained reduction of intraocular pressure in glaucoma patients treated concomitantly with timolol.

The long term effects of two dose regimens of latanoprost (PhXA41) administered to eyes concomitantly treated with timolol which had not adequately been controlled by timolol alone were compared. A total of 50 patients, 17 with primary open angle glaucoma and 33 with capsular glaucoma, were recruited from five clinics. All had glaucomatous visual field defects and an intraocular pressure (IOP) of at least 22 mm Hg despite treatment with 0.5% timolol twice daily. Patients were randomised to two treatment groups. In one group 0.006% latanoprost was given twice daily, in the other group placebo was given at 8 am and latanoprost at 8 pm for 3 months, with concomitant timolol treatment in both groups. Average daytime IOP (mean (SD)) at baseline (on timolol alone) and after 4 and 12 weeks' treatment was 24.8 (3.6), 16.8 (4.3), and 15.7 (2.4) mm Hg respectively with once daily application of latanoprost and 24.9 (2.9), 18.1 (3.0), and 18.0 (3.6) mm Hg respectively with latanoprost twice daily. No clinically significant side effects were observed during treatment. Latanoprost causes a marked and sustained IOP reduction in eyes which are also being treated with timolol. Latanoprost given once daily is at least as effective and probably superior to a twice daily dose regimen.