A six-week dose-response study of the ocular hypotensive effect of dorzolamide with a one-year extension. Dorzolamide Dose-Response Study Group.
OBJECTIVE
To investigate the efficacy and dose-response relationship of three concentrations (0.2%, 0.7%, and 2.0%) of dorzolamide hydrochloride in lowering elevated intraocular pressure (IOP) in patients during a six-week period and to evaluate the efficacy of 0.7% and 2.0% dorzolamide administered for an additional year.


METHODS
This prospective, double-masked, randomized, placebo-controlled, multinational study enrolled 333 adults with open-angle glaucoma or ocular hypertension. During the six-week dose-response phase, patients were randomized to thrice-daily dosing of four treatments: 0.2%, 0.7%, or 2.0% dorzolamide or placebo (vehicle of dorzolamide). During a one-year extension, patients received 0.7% or 2.0% dorzolamide, and, if needed, 0.5% timolol twice daily for elevated IOP.


RESULTS
In the dose-response phase, mean percent reduction of IOP (peak) was 16% to 18% for 2.0% and 0.7% dorzolamide and 4% to 7% for the placebo group, for a net reduction of IOP by dorzolamide of 11% to 14%. The 0.2% concentration of dorzolamide was not sufficiently active for further consideration. During the extension, dorzolamide maintained an adequate reduction of IOP in 55% (174 of 316) of patients. Throughout the study, the reduction in IOP was numerically greater for patients receiving 2.0% vs 0.7% dorzolamide. After 12 months of receiving dorzolamide, 20% to 28% of total carbonic anhydrase activity was observed.


CONCLUSIONS
Topical dorzolamide used three 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% timolol.
Strahlman
E
E
Merck & Co., Inc., West Point, Pennsylvania, USA.
Tipping
R
R
Vogel
R
R
D000287:Administration, Topical; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy*; D009883:Ophthalmic Solutions; D011446:Prospective Studies; D013449:Sulfonamides / Q000008:administration & dosage* / Q000009:adverse effects; D013876:Thiophenes / Q000008:administration & dosage* / Q000009:adverse effects; D013999:Timolol / Q000008:administration & dosage
D002257:Carbonic Anhydrase Inhibitors; D004338:Drug Combinations; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013876:Thiophenes; D013999:Timolol; C062765:dorzolamide