Preliminary investigations of a new beta-adrenoceptive receptor blocking drug, LB46, in man.

1. Preliminary studies in man of a new beta-adrenoceptive receptor blocking drug, DL-4-(2-hydroxy-3-isopropylaminopropoxy)-indole (LB46), are described.2. LB46, 0.5 mg by oral administration, appeared to be of similar potency to propranolol 20 mg in inhibiting isoprenaline-induced and exercise-induced tachycardia.3. In comparable beta-receptor blocking doses LB46 did not show the negative chronotropic property possessed by propranolol.