The efficacy and safety of dorzolamide as adjunctive therapy to timolol maleate gellan solution in patients with elevated intraocular pressure. Additivity Study Group.
OBJECTIVE
Two parallel, randomized, double-masked, placebo-controlled studies were conducted to assess the efficacy and safety of 2% dorzolamide hydrochloride as adjunctive therapy to 0.5% timolol maleate ophthalmic gellan (gel-forming) solution in patients with elevated intraocular pressure (IOP) that was inadequately controlled with 0.5% timolol maleate gellan solution alone.


METHODS
Both studies began with an open-label 2-week run-in period on 0.5% timolol maleate gellan solution once a day. The only variation in method between the two studies was the dosage of 2% dorzolamide. In one study, 202 patients received 0.5% timolol maleate gellan solution once daily plus either 2% dorzolamide or placebo three times daily. In the other study, 181 patients received 0.5% timolol maleate gellan solution once daily plus either 2% dorzolamide or placebo twice daily.


RESULTS
After 85 days, additional mean percent reductions in IOP from baseline at morning trough for the groups receiving 2% dorzolamide three times daily and placebo three times daily were 12.5% and 8.4%, respectively. Mean percent reductions for the groups receiving 2% dorzolamide twice daily and placebo twice daily were 13.1% and 6.5%, respectively. Burning and/or stinging on instillation were the only adverse experiences that affected significantly more of the patients receiving 2% dorzolamide twice or three times daily than those receiving placebo.


CONCLUSIONS
When administered concomitantly with 0.5% timolol maleate gellan solution, 2% dorzolamide three times daily or twice daily produced a statistically significant reduction in IOP at morning trough and peak and was generally well tolerated.
Adamsons
I
I
Department of Clinical Research, Merck Research Laboratories, West Point, Pennsylvania, USA.
Clineschmidt
C
C
Polis
A
A
Taylor
J
J
Shedden
A
A
Laibovitz
R
R
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D005260:Female; D005782:Gels; D006801:Humans; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy*; D012996:Solutions; D013449:Sulfonamides / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D013876:Thiophenes / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D013999:Timolol / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D000319:Adrenergic beta-Antagonists; D002257:Carbonic Anhydrase Inhibitors; D005782:Gels; D012996:Solutions; D013449:Sulfonamides; D013876:Thiophenes; D013999:Timolol; C062765:dorzolamide