The effects of atenolol (tenormin) and methyldopa on simple tests of central nervous function.

Two identical studies, one comparing the effect of single doses of a new beta-adrenoceptor blocker, atenolol (Tenormin) (50 mg and 100 mg) and placebo, and the other comparing the effect of single doses of methyldopa (250 mg and 500 mg) and placebo, in healthy volunteers, were carried out. 2 In both studies the effect of the drugs upon reaction time, critical flicker frequency, subjective drowsiness, pulse rate and blood pressure was measured. 3 Atenolol produced no effect upon reaction time, critical flicker frequency or subjective feelings, while methyldopa produced a statistically significant prolongation of reaction time and a statistically significant increase in the subjective sensation of drowsiness. 4 Atenolol produced statistically significant reductions in systolic and diastolic blood pressure and in pulse rate while methyldopa was without effect. 5 It is concluded that atenolol is unlikely to produce the side effects of sedation or drowsiness.