The effects of high doses of oxprenolol and of propranolol on pursuit rotor performance, reaction time and critical flicker frequency.

The effects of oral oxprenolol (320 mg) or propranolol (240 or 320 mg) and of diazepam (5 mg) or lorazepam (2 mg) on pursuit rotor performance, reaction time and critical flicker frequency were investigated in healthy subjects in 3 separate studies. A 240-mg dose of propranolol significantly impaired pursuit rotor performance but not 320 mg of propranolol or oxprenolol. Both beta-adrenoceptor blockers did not affect reaction time or critical flicker frequency. Diazepam impaired pursuit rotor performance and reaction time, but not critical flicker frequency. Lorazepam generally impaired all three parameters. The findings suggest that it is possible for beta-adrenoceptor blockers to depress skeletal muscle activity without having a central effect, as shown by impairment of CNS function tests which rely also on muscle coordination but not of those relying only on central activity. These results also show that single oral doses of oxprenolol or propranolol, as high as 320 mg, do not have central effects, and support the belief that small anxiolytic doses of these blockers exert their actions through peripheral blockade of beta-adrenoceptors.