Comparing the fixed combination dorzolamide-timolol (CosoptR) to concomitant administration of 2% dorzolamide (TrusoptR) and 0.5% timolol - a randomized controlled trial and a replacement study

Abstract

The results of the randomized trial indicate that the fixed combination dorzolamide-timolol (Cosopt) was as effective as its components in controlling IOP, confirming results seen in phase 3 clinical trials. However, in the replacement study, utilization of the combination drug offered a statistically significant additional IOP reduction (P < 0.0001), which duplicates results from previous replacement studies.

Considerations in glaucoma therapy: fixed combinations versus their component medications

“…Several open-label replacement studies have suggested that patients may achieve additional IOP lowering when they are switched from dorzolamide and a beta-blocker to FCDT 16–19. It should be noted that Phase IV trials such as these are subject to bias, because the investigators are not masked and the study design may influence the study outcomes.…”

“…For example, in 2 of the studies16,17 patients were allowed to be on a selective beta-blocker before switching to FCDT, and in all 4 studies, there was a possibility of improved adherence after patients entered the study and switched to FCDT. Francis et al19 reported a randomized parallel-group study of FCDT and concomitant therapy as well as a study of FCDT replacement of concomitant therapy, and although the efficacy results favored FCDT in the replacement study, the randomized controlled trial demonstrated equivalent efficacy of FCDT and concomitant dorzolamide plus timolol therapy. Overall, the results of these studies suggest that FCDT and concomitant dorzolamide plus timolol therapy have similar efficacy in lowering IOP.…”

Effectiveness of Dorzolamide–Timolol (COSOPT) in Patients Who Were Treatment Naive for Open-Angle Glaucoma or Ocular Hypertension: The COSOPT First-Line Study

“…Overall, data from clinical trials have shown that dorzolamide and timolol are both efficacious while being generally safe and well tolerated. [21][22][23][24] In addition, more recent studies have shown that a fixed combination of dorzolamide-timolol (DT) was more effective in reducing IOP when compared with monotherapy with either one, [24][25][26][27][28] most likely because of increased compliance or decreased washout effect associated with its fixed formulation. These studies suggest that for patients who do not respond to initial monotherapy the use of combination therapy may be of benefit.…”

Efficacy of antiglaucoma fixed combination therapy versus unfixed components in reducing intraocular pressure: a systematic review

“…Many randomised controlled trials8 – 15 have addressed efficacy for mono-therapy and various fixed combination therapies as a first-line management of glaucoma. Of the systematic reviews, some have compared single therapies,16 17 Burr et al 18 compared single therapies with surgery, and Webers et al 19 included studies that investigated use of fixed combinations and concomitant use of single agents.…”