A comparison of the effects of timolol and epinephrine on intraocular pressure.

We conducted a double-masked, six-week crossover study comparing bilateral twice-a-day therapy with timolol maleate (0.1%, 0.25%, and 0.5%) and epinephrine hydrochloride (0.5%, 1.0%, 2.0%) in 36 otherwise untreated patients. Increasing concentrations of each drug were administered until an arbitrary level of control was achieved before each of the six-week follow-up periods. Seventeen patients were controlled by both drugs and four patients were controlled by neither drug. Timolol, but not epinephrine, was effective in ten patients, whereas epinephrine, but not timolol, was effective in two patients. Three patients did not complete the study. The mean decrease in intraocular pressure from baseline was significantly greater with timolol than with epinephrine both before crossover and overall at both the lowest and highest concentrations of drug used. Significantly toxicity was produced in four patients during treatment with epinephrine, but in no patients during treatment with timolol.