Central mechanisms of clonidine and propranolol in man. Quantitative Pharmaco-EEG with antihypertensive compounds.

Direct CNS effects of clonidine (0.2 mg) and propranolol (40 mg and 80 mg) were established in healthy young male subjects within three hours after oral administration. They were demonstrated in two studies using procedures of the Quantitative Pharmaco-EEG (QPEEG) method. Quantitatively, the greatest CNS effects were attained with 0.2 mg clonidine followed by 80 mg, and finally by 40 mg propranolol. Based on the computer-analyzed EEG (CEEG) profiles obtained and using the HZI Research Center CEEG data base, the psychotropic properties of these compounds were predicted. Propranolol, in the 40-mg dose, showed a similarity to vigilance-enhancing compounds, whereas the 80-mg dose and the 0.2-mg dose of clonidine were established as primarily similar to mood-elevating (sedative antidepressant) drugs. However, despite some overall similarities in the mode of action between the high dose of propranolol and the clonidine, some differences in their CNS effects were detected based on their secondary effects (anxiolytic and sedative effects, respectively).