Dorzolamide/timolol combination has hypotensive and haemodynamic effects

A fixed combination of dorzolamide and timolol significantly increase blood flow at the neuroretinal rim, demonstrating a combination of hypotensive and haemodynamic effects, according to a report published online ahead of print by Eye.

Teresa Rolle and colleagues from the University of Torino, Italy compared the effect of dorzolamide hydrochloride 2%, timolol maleate 0.5% and their fixed combination on intraocular pressure (IOP) and retinal and optic nerve head haemodynamics in 28 patients with primary open angle glaucoma.

After a four-week wash-out period, patients were randomized into two groups: group 1 received dorzolamide 2% monotherapy and group 2 received timolol 0.5% monotherapy. Following this period, both groups switched to a fixed combination of the two drugs for four-weeks. IOP, ocular diastolic perfusion pressure (ODPP), heart rate and scanning laser Doppler flowmetry measurements at the peripapillary retina and neuroretinal rim were taken at enrolment (T0), wash-out (T1), during monotherapy (T3) and during combination therapy (T4).

At T1 and T3, IOP had decreased significantly in group 1 (p<0.001) and in group 2 (p<0.001). At the same intervals, blood flow increased significantly at rim level in group 1 (p<0.05). Between intervals of T1 and T3, a significant increase in ODPP was observed in both groups.

The authors of this study believe that a fixed combination of dorzolamide and timolol significantly increases blood flow at the neuroretinal rim.