The 24-Hour Effects of Brinzolamide/Brimonidine Fixed Combination and Timolol on Intraocular Pressure and Ocular Perfusion Pressure

Purpose: To determine the 24-h effects of brinzolamide/brimonidine tartrate 1%/0.2% fixed combination (BBFC) on intraocular pressure (IOP), ocular perfusion pressure (OPP), blood pressure (BP), and heart rate (HR). Methods: Sixty subjects with open angle glaucoma (OAG) or ocular hypertension (OHTN) were admitted overnight for 24-h monitoring of IOP, BP, and HR. All subjects underwent the first, baseline 24-h study after washout of all medications, if necessary. Subjects were then randomized to receive either (1) timolol maleate 0.5% twice daily or (2) BBFC 3 times daily. After 4 weeks of treatment, all subjects completed a follow-up 24-h study visit. At each study visit, IOP, BP, and HR were measured every 2-h in the habitual position. OPP was calculated as 2/3[diastolic BP + 1/3(systolic BP-diastolic BP)]-IOP. Results: Treatment with BBFC significantly lowered IOP during the diurnal period (-2.7 +/- 0.4 mmHg; P < 0.01) and nocturnal period (-0.8 +/- 0.3 mmHg; P < 0.01). Timolol similarly reduced IOP during the diurnal period, but did not lower IOP overnight. Over a 24-h period, BBFC achieved a significantly greater IOP reduction than timolol (-0.7 +/- 0.4 mmHg; P = 0.04). BBFC failed to achieve an increase in OPP during any time period, while timolol increased OPP during the diurnal period only. A significantly greater reduction in HR occurred in the timolol group. Conclusions: BBFC significantly lowers IOP during both the diurnal and nocturnal periods, but has no effect on OPP. Timolol only lowers IOP during the diurnal period.