Background: Prostaglandin analogues are effective ocular hypotensive agents and are being used increasingly in the treatment of elevated intraocular pressure (IOP). These agents are typically dosed once daily.
Objectives: A pilot study was conducted to evaluate the duration of travoprost's IOP-lowering efficacy up to 84 hours after the final dose in patients with open-angle glaucoma. A follow-up study was conducted to compare diurnal IOP control with travoprost and latanoprost over a 44-hour period.
Methods: In the open label pilot study, patients received 0.004% travoprost in both eyes at 8 pm daily for 2 weeks. After 2 weeks, IOP was measured before administration of the last daily dose, every 4 hours thereafter for 36 hours, and 60 and 84 hours after the last dose, with no additional ocular hypotensive medication given. In the controlled, double-masked, parallel-group, follow-up study, patients were randomized to self-administer 1 drop of the marketed doses of 0.004% travoprost or 0.005% latanoprost in both eyes at 8 pm daily for 2 weeks. At the end of this period, patients returned to the facility at approximately 8 pm for IOP measurement and administration of the final dose of study medication. IOP was then measured at 4-hour intervals for 44 hours after the last dose, with no additional ocular hypotensive medication given.
Results: The pilot study included 21 patients (67% female, 33% male; age range, 35-81 years) with open-angle glaucoma. IOP values were significantly below baseline at all time points up to 84 hours after the final dose of travoprost ( P<0.001). The follow-up study enrolled 35 patients, 1 of whom was excluded for missing data; thus, the intent-to-treat analysis included 34 patients (68% female, 32% male; age range, 36-72 years). At the unmedicated eligibility visit, mean IOP over 24 hours ranged from 21 to 26 mm Hg in each treatment group. After 2 weeks of treatment and 24 hours after the last dose, mean (SD) IOP was 13.1 (2.1) mm Hg (change from eligibility visit, -10.4 [2.7] mm Hg) in the travoprost group and 16.0 (3.1) mm Hg (change from eligibility visit, -7.1 [2.4] mm Hg) in the latanoprost group. The difference in change from baseline was statistically significant between treatment groups (P=0.006). Travoprost lowered IOP significantly at all time points throughout the 44-hour period after the last dose (mean IOP, <or=18 mm Hg; [P<0.001) and was statistically superior to latanoprost at 8 pm before the last dose (P=0.041) and 24 hours after the last dose (P=0.006). Latanoprost showed greater IOP-lowering efficacy compared with travoprost 4 hours after the last dose (P=0.040). IOP reductions were significantly different from zero at all time points with both treatments (P<0.001).
Conclusions: The results of the pilot study suggest that travoprost produces reductions in IOP that may be sustained for up to 84 hours after dosing. The results of the follow-up study suggest that both prostaglandin analogues significantly lower IOP from baseline in patients with open-angle glaucoma and provide excellent diurnal IOP control throughout a 24-hour period.