A double-masked, placebo-controlled evaluation of timolol in a gel vehicle

We evaluated a topical formulation of timolol in an anionic heteropolysaccharide gellan gum (Gelrite). Fifty-five white patients with ocular hypertension entered a double-masked, placebo-controlled, four-period, incomplete block crossover study. After washout of any ocular hypotensive medications, the intraocular pressure of both eyes of all patients was measured at 0 (09:00 h), 2, 4, 6, 8, 12, and 24 h (diurnal baseline). Patients were then randomized to receive, at 2-week intervals, one drop of each of four of the six treatments in one eye (0.008% timolol gel, 0.1% timolol gel, placebo gel, 0.008% timolol solution, 0.1% timolol solution, and placebo solution). Fellow eyes received the appropriate placebo. As measured by least-squares means, adjusted for the unmedicated baseline diurnal values, there was a clear dose-response, with the 0.1% treatments being more effective ocular hypotensive agents than the 0.008% treatments, which in turn were more effective than the placebo treatments. Within each concentration at several observation points, the gel formulation elicited a 1-2-mm Hg greater efficacy than the solution. Gel-treated subjects had a greater incidence of blurred vision. We conclude that formulation of timolol with a gel may increase efficacy, and thus duration of action. This may possibly allow use of a lower concentration of timolol or a reduced frequency of instillation. Further evaluation in chronic dosing studies is justified.