A controlled clinical trial of Dorzolamide: a single-centre subset of a multicentre study

Purpose: To assess the safety and intraocular pressure (IOP)-lowering activity of 2% dorzolamide (topical carbonic anhydrase inhibitor), compared to 0.5% timolol and 0.5% betaxolol eyedrops.
Methods: A parallel, masked, randomised one-year clinical trial was conducted in 16 patients with open-angle glaucoma or ocular hypertension, being a subset of a multicentre study which enrolled 523 subjects. Patients had IOP > 22 mmHg in one eye at baseline following washout of ocular hypotensive medications and were then randomised in a 3:l:l ratio to receive 2% dorzolamide thrice daily, 0.5% timolol twice daily or 0.5% betaxolol twice daily respectively. IOP was measured at Hour 2 (morning peak), Hour 5 and Hour 8 (afternoon trough for dorzolamide) at baseline, Weeks 2 and 4 and Months 2, 3, 6, 9 and 12.
Results: Topical dorzolamide 2% solution was well tolerated and safe. Mean IOP for dorzolamide at Hour 2 was 29.1 mmHg at baseline and 20.8 mmHg on treatment at one year, a 28.5% change. Mean IOP for dorzolamide at Hour 8 was 24.5 mmHg at baseline and 20.2 mmHg on treatment at one year, a 17.6% change. Comparable percent changes for timolol and betaxolol were 43.2/25.7 mmHg at Hour 2 and 21.9/13.5 mmHg at Hour 8 respectively.
Conclusions: Dozolamide 2% given thrice daily was well tolerated and safe, with a clinically significant effect on IOP comparable to betaxolol 0.5% twice daily, but not as great as timolol 0.5% twice daily.