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 less than .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.