Pharmacological studies of 1-(o-chlorophenyl)-2-tert.-butylaminoethanol (C-78), a new bonchodilator.

The bronchodilating effects and other related pharmacological properties of 1-(o-chlorophenyl)-2-tert.-butylaminoethanol-hydrochloride (C-78) were studied in comparison with those of isoproterenol, salbutamol and clorprenaline. C-78 was found to produce a bronchodilating effect 2--10 times stronger and considerably weaker than clorprenaline and isoproterenol, respectively. However, the bronchodilating effect of C-78 was sustained more than 10 times as long as those of isoproterenol and sulbutamol and, especially on oral administration, it was much more potent. The bronchodilating effect of C-78 seems to be due to excitation of the adrenergic beta-receptor, and was antagonized by propranolol. The positive chronotropic and inotropic effects of C-78 on an isolated atrial preparation were less than 1/1000 as potent as those of isoproterenol. C-78 also decreased the tone of smooth muscle, such as the uterus, but its affinity for the bronchial muscle is much higher than for the uterus. C-78 showed strong anti-anaphylactic action and strongly promoted the tracheal ciliary movement. Anitussive effect was also demonstrated, though this was inferior to that of codeine, however, there was no influence on bronchosecretion.