EVALUATION OF TIMOLOL IN GELLAN GUM - A NEW VEHICLE TO EXTEND ITS DURATION OF ACTION

Timolol, a nonspecific beta-adrenergic antagonistic used for the treat ment of elevated intraocular pressure (IOP), is usually applied every 12 hours. To reduce its frequency of application, while IOP lowering i s achieved, requires enhancement of its duration of action. The reside nce time of the drug was increased with a vehicle that changes from a sol to a gel on contact with the tear film, thereby extending the time for drug absorption. Each of 21 patients with IOPs greater the 22 mmH g at 9 a.m. was stratified by iris color and assigned to receive eithe r timolol in gellan gum (Gelrite, Merck, Whitehouse Station, NJ) 0.5% every 24 hours OU or timolol 0.5% every 12 hours OU. Fourteen patients were randomized to the timolol-in-gellan gum group and seven to the t imolol-alone group. The patients and physicians were masked. At each s ubsequent visit, the IOP was measured at 9 a.m. before the use of the study medication and two hours later. There were a total of seven visi ts over the 24-week period. Based on the statistical analysis of our d ata, timolol in gellan gum, after a single daily instillation in the m orning, is comparable to timolol solution used every 12 hours to lower IOP. The prolongation of IOP reduction appears to be due to an increa se in the residence time of the drug, which is produced by the gellan gum vehicle. Blurred vision was a reported side effect.