The assessment of the beta-adrenoceptor blocking activity and cardioselectivity of Koe 3290 in normal subjects.

1. The beta-adrenoceptor antagonist activity, cardioselectivity and antilipolytic properties of Koe 3290 were investigated in healthy subjects. 2. Koe 3290 12.5, 25, 50 and 100 mg, atenolol 25, 50 and 100 mg and placebo were given in double-blind randomised order to eight subjects. All doses of both Koe 3290 and atenolol reduced supine, standing and exercise heart rate (P less than 0.02). From 2 to 8 h after administration the exercise heart rate after Koe 3290 100 mg was similar to that for atenolol 50 mg. 3. The cardioselectivity of Koe 3290 and atenolol was compared. Koe 3290 50, 100 and 150 mg, atenolol 50 and 100 mg and placebo were given to six subjects in a double-blind random order. Isoprenaline dose-response curves were constructed for cardiovascular parameters and finger tremor. 4. For doses which were equipotent at the beta 1-adrenoceptor (Koe 3290 100 mg and atenolol 50 mg) atenolol caused less attenuation of heart rate, diastolic blood pressure, forearm blood flow and finger tremor (P less than 0.02). 5. There was no difference in the isoprenaline-induced changes in serum free fatty acids, blood glucose, plasma lactate or potassium after Koe 3290 and atenolol. Koe 3290 attenuated the rise in serum insulin more than atenolol (P less than 0.02). 6. Koe 3290 is an effective beta-adrenoceptor blocking drug in man. It is not as cardioselective as atenolol and does not possess specific antilipolytic properties.