Comparison of dorzolamide and pilocarpine as adjunctive therapy in patients with open-angle glaucoma and ocular hypertension

Many patients with glaucoma or ocular hypertension initially receive beta-blocker monotherapy to control intraocular pressure (IOP), but some of these patients will require an additional IOP-lowering agent within 1 year. This active-controlled, double-masked, randomized, multicenter, 12-week study compared the effectiveness and tolerability of dorzolamide hydrochloride ophthalmic solution 2% TID with those of pilocarpine hydrochloride 2% QID as adjunctive therapy to timolol maleate ophthalmic gel-forming solution (TG) 0.5% QD as measured by changes in IOP and occurrence of adverse events. One hundred ninety-four patients with open-angle glaucoma or ocular hypertension participated in this study. Their mean age was ~63 years. Slightly more than one half were white, and approximately one third were black. After a 3-week run-in period during which all patients received TG 0.5% QD, patients with an IOP of ≥22 mm Hg at the morning trough measure- ment were randomly assigned to receive additional double-masked therapy with either dorzolamide or pilocarpine. The primary outcome measure was the mean change in IOP at the morning trough measurement from baseline to week 12. The secondary outcome measure was the mean change in IOP at the morning peak measurement from baseline to week 12. There was no significant difference in IOP-lowering effect between the 2 drugs at either morning trough or morning peak. The mean change in IOP at morning trough was −3.17 mm Hg (−12%) in patients receiving dorzolamide; it was −3.45 mm Hg (−13%) in patients receiving pilocarpine. The mean change in IOP at morning peak was −2.25 mm Hg (−10%) for patients who received dorzolamide and −2.51 mm Hg (−11%) for those who received pilocarpine. In the pilocarpine group, 62 (63%) patients experienced ≥1 adverse event compared with 35 (36%) patients in the dorzolamide group (P < 0.001). Twenty-one (21%) patients in the pilocarpine group discontinued treatment because of an adverse event compared with 2 (2%) patients in the dorzolamide group (P < 0.001). These results demonstrate that dorzolamide and pilocarpine were equally effective as adjunctive therapy in lowering IOP but that dorzolamide was better tolerated.