Greater IOP control seen with bimatoprost in study

Dr. Cantor and colleagues conducted a multicenter prospective, randomized, investigator-masked, parallel-group comparison of the two antiglaucoma medications because results of previous studies showed their efficacy. Dr. Cantor is the Jay C. and Lucille L. Kahn Professor of Glaucoma Research and Education and director of glaucoma services, Department of Ophthalmology, Indiana University Medical Center, Indianapolis.

"Bimatoprost 0.05% is a potent and highly efficacious monotherapy that allows many patients to achieve low target pressure," they reported. "Furthermore, several clinical trials have demonstrated that bimatoprost monotherapy provides IOP lowering [that is] more effective than either latanoprost [Xalatan, Pfizer] or timolol [Timoptic, Merck]. Bimatoprost is a prostamide and reduces IOP by increasing both pressure-sensitive (presumed trabecular meshwork) and pressure-insensitive (presumed uveoscleral) outflow.

The study included 157 patients randomly assigned to treatment with either bimatoprost 0.03% (n = 76) or travoprost 0.004% (n = 81) for 6 months. They were instructed to instill their medication between 7 and 9 p.m. each day. All patients had a clinical diagnosis of either open-angle glaucoma or ocular hypertension. Patients went through a washout period before starting treatment with the trial drugs. After the washout period, the untreated IOP was 21 mm Hg or higher and did not exceed 34 mm Hg. No significant differences were observed between the patients in both groups at baseline; the mean 9 a.m. IOP at baseline was 24.6 ± 3.3 mm Hg in the bimatoprost group and 24.4 ± 3.2 mm Hg in the travoprost group. The investigators were masked to the study drugs, and all IOP readings were masked as well.

The patients were examined at baseline, 1 week after the start of treatment, and 1, 3, and 6 months after the start of treatment. The patients' IOP levels were measured at 9 a.m. at every visit and at 1 and 4 p.m. at baseline and at the 3- and 6-month visits to allow the investigators to assess the diurnal IOP, Dr. Cantor explained.

Of the 76 patients who received bimatoprost, 93.4% completed the study. Of the 81 patients who received travoprost, 86.4% completed the study.

In the bimatoprost group, two patients were lost to follow-up and four had adverse events (blurry vision and photophobia, ocular redness, and lid erythema). In the travoprost group, four patients left the study because of lack of efficacy of the drug, five had adverse events (ocular redness and lid erythema, ocular dryness and itching, and allergic conjunctivitis), and two were lost to follow-up.

The results indicated that bimatoprost was more effective at each time point compared with travoprost.

"Both study medications provided statistically significant IOP reductions from baseline at 9 a.m. at all study visits (p ≤0.001), but the mean reductions in the bimatoprost group were significantly (p ≤0.014) greater than the reductions in the travoprost group at every study visit," the investigators reported. The mean IOP reductions with bimatoprost ranged from 7.1 to 8.2 mm Hg (28% to 33%), and the mean IOP reductions with travoprost ranged from 5.7 to 6.5 mm Hg (23% to 26%).

IOP reductions in afternoon