Therapeutic equivalence of Galaxia(R) : a new formulation of generic latanoprost : Vs Xalatan(R): the results of a multicenter randomized clinical trial

Purpose:to verify the therapeutic equivalence of a new formulation of generic latanoprost (Galaxia®) vs Xalatan® in lowering IOP in primary open-angle glaucoma (POAG) or ocular hypertensive (OH) patients. Methods:The study was a phase III, multicenter, prospective, randomized, double-blind, parallel-group clinical trial comparing generic latanoprost with Xalatan® in 185 POAG or OH patients, with an intraocular pressure (IOP) > 21 mmHg at the randomization visit.Patients were instructed to instill one drop in the affected eye(s) every evening at 8:00 p.m. for 12 weeks. The primary efficacy endpoint was the change in IOP (mean of the three assessments) from baseline after 12 weeks of treatment. The equivalence of the 2 latanoprost formulations was analyzed by means of an ANCOVA model including treatment as fixed effect and baseline IOP value as covariate. The two-sided 95% confidence intervals for the difference between Least Squares (LS) means for the two treatment groups was calculated. The two treatments were to be declared equivalent if the two-sided 95%CI for the difference between adjusted treatment means of the three measurements lay entirely within the interval -1.5 to +1.5 mmHg. The sample size was calculated setting the power of the study at 80% to show the equivalence at a 5% significance level, assuming a standard deviation of IOP of 3 mmHg and setting the equivalence limits at -1.5 and +1.5 mmHg Results:The mean difference in the reduction achieved with the two treatments was 0.1 mmHg and its confidence interval (-0.47; +0.71) fell within the interval set for therapeutic equivalence. Both treatments were equally well tolerated and only one patient in each treatment group withdrew from the study due to adverse event. Conclusions:this 12-week study demonstrates that the generic Galaxia® and Xalatan® are equally effective IOP-lowering treatments.