The use of dorzolamide and pilocarpine as adjunctive therapy to timolol in patients with elevated intraocular pressure. The Dorzolamide Additivity Study Group.
OBJECTIVE
To report the results of two studies on the use of dorzolamide as adjunctive therapy to timolol in patients with elevated intraocular pressure (IOP). In the larger study, the additive effect of dorzolamide administered twice daily also was compared with 2% pilocarpine.


METHODS
Both studies were parallel, randomized, double-masked, placebo-controlled comparisons. In the pilot study, 32 patients received 0.5% timolol twice daily plus either 2% dorzolamide twice daily or placebo twice daily for 8 days. In the Pilocarpine Comparison Study, 261 patients received 0.5% timolol twice daily plus 0.7% dorzolamide twice daily, 2% dorzolamide twice daily, 2% pilocarpine four times daily, or placebo (twice daily or 4 times daily) for 2 weeks. Patients then entered a 6-month extension period and received 0.5% timolol twice daily plus either 0.7% dorzolamide twice daily, 2% dorzolamide twice daily, or 2% pilocarpine four times daily.


RESULTS
In the pilot study, after 8 days, additional mean percent reductions in IOP for 2% dorzolamide and placebo were 17% and 3% at morning trough and 19% and 2% at peak, respectively. In the Pilocarpine Comparison Study, after 6 months, additional mean percent reductions in IOP (morning trough) were 9%, 13%, and 10% for 0.7% dorzolamide, 2% dorzolamide, and 2% pilocarpine, respectively. Patients receiving 2% pilocarpine had the highest rate of discontinuation due to a clinical adverse experience, and the use of dorzolamide was not associated with systemic side effects commonly observed with the use of oral carbonic anhydrase inhibitors.


CONCLUSIONS
Dorzolamide twice daily was effective and well tolerated by the patients in these studies as adjunctive therapy to timolol. The larger study demonstrated that both concentrations of dorzolamide produce similar IOP-lowering effects to 2% pilocarpine.
Strahlman
E R
ER
Department of Clinical Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
Vogel
R
R
Tipping
R
R
Clineschmidt
C M
CM
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*; D017024:Chemotherapy, Adjuvant; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D018721:Muscarinic Agonists / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D009798:Ocular Hypertension / Q000188:drug therapy*; D009883:Ophthalmic Solutions; D010862:Pilocarpine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D010865:Pilot Projects; D012449:Safety; 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; D018721:Muscarinic Agonists; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013876:Thiophenes; D010862:Pilocarpine; D013999:Timolol; C062765:dorzolamide