A comparison between 2% dorzolamide/0.5% timolol fixed combination: brand name drug to its generic counterpart regarding efficacy and side effects

The aim of this study was to compare 2% dorzolamide/0.5% timolol fixed combination brand name drug (Cosopt) to its generic counterpart (Twinzol) regarding efficacy and side effects. The study included 92 eyes of 92 patients diagnosed with primary open-angle glaucoma and are indicated for antiglaucoma fixed combination of 20 mg/ml dorzolamide/5 mg/ml timolol). Patients were randomly divided into two groups: the first group received Cosopt, whereas the second received Twinzol. In visit, intraocular pressure (IOP) was measured and any local side effects by either eye drops was recorded. Monitoring and recording the percentage of IOP drop each month and all over the 3 months duration of follow up visits were done. The percentage of IOP drop for Cosopt and Twinzol after 1 month showed a significant P value of 0.032, with a mean percent reduction in IOP of 28.55%, median percent reduction of 26.92%, the minimum is 3.82% while the maximum is 62.96% for the Cosopt group, while that for Twinzol was 23.14, 21.29, 4.17, and 57.14%, respectively. On the other hand, the percentage of drop of IOP between the two groups after 3 months showed insignificant P value (0.646). IOP measurement was statistically insignificant between the two groups at 1 (0.462) and 3 months (0.639). As regards side effects; both eye drops were comparable with an insignificant P value of 0.49. The study demonstrated a reliable efficacy and safety on using generic therapy Twinzol compared with band counterpart Cosopt.