Cardiovascular effects of topical beta-blockers during exercise

In two different medical centers, a total of 24 normal individuals (mean age, 31 years) participated in a double-masked, three-way crossover single-instillation comparison of betaxolol 1%, timolol 0.5%, and placebo. After each ocular treatment, cardiovascular characteristics were measured during ten-minute treadmill exercise periods. No significant differences in heart rate or double product (heart rate x systolic pressure) were seen between treatment with betaxolol and administration of placebo. However, when the same subjects were treated with timolol, they demonstrated significant (P<.05) reductions in these values at various measurement times compared with placebo and betaxolol treatments. No significant differences in mean arterial pressure were detected after any of the treatments.