A 6-WEEK DOSE-RESPONSE STUDY OF THE OCULAR HYPOTENSIVE EFFECT OF DORZOLAMIDE WITH A ONE-YEAR EXTENSION

PURPOSE: To investigate the efficacy and dose-response relationship of three concentrations (0.2%, 0.7%, and 2.0%) of dorzolamide hydrochlor ide in lowering elevated intraocular pressure (IOP) in patients during a six week period and to evaluate the efficacy of 0.7% and 2.0% dorzo lamide administered for an additional year. METHODS: This prospective, double-masked, randomized, placebo-controlled, multinational study en rolled 333 adults with open-angle glaucoma or ocular hypertension, Dur ing the six week dose-response phase, patients were randomized to thri ce-daily dosing of four treatments: 0.2%, 0.7%, or 2.0% dorzolamide or placebo (vehicle of dorzolamide), During a one-year extension, patien ts received 0.7% or 2.0% dorzolamide, and, if needed, 0.5% timolol twi ce daily for elevated IOP. RESULTS: In the dose-response phase, mean p ercent reduction of IOP (peak) was 16% to 18% for 2.0% and 0.7% dorzol amide and 4% to 7% for the placebo group, for a net reduction of IOP b y dorzolamide of 11% to 14%, The 0.2% concentration of dorzolamide was not sufficiently active for further consideration, During the extensi on, dorzolamide maintained an adequate reduction of IOP in 55% (174 of 316) of patients, Throughout the study, the reduction in IOP was nume rically great er for patients receiving 2.0% vs 0.7% dorzolamide, Afte r 12 months of receiving dorzolamide, 20% to 28% of total carbonic anh ydrase activity was observed, CONCLUSIONS: Topical dorzolamide used th ree times daily in concentrations of 0.7% or 2.0% lowered IOP and was generally well tolerated as monotherapy or in combination with 0.5% ti molol.