α-[(t-Butylamino)methyl]-4-hydroxy-m-xylene-α¹, α³-diol (AH.3365): a Selective β-Adrenergic Stimulant

Abstract

α-[(t-Butylaraino)methyl]-4-hydroxy-m-xylene- α¹, α³-diol (AH.3365), one of a new series of β-adrenergic stimulants described in the preceding communication, when tested on animals has been found to have a considerably greater action on bronchial smooth muscle than on other smooth muscles affected by β-stimulants. Relative potencies found for AH.3365, isoprenaline and orciprenaline in preventing bronchospasm induced by acetylcholine in guinea-pigs are given in Table 1 together with their potencies in relaxing spontaneous tone of isolated tracheal chain preparations. In the Konzett–Rössler preparation, similar orders of potency were found when the spasmogen used was histamine, 5-hydroxytryptamine or bradykinin. At equi-effective doses AH.3365 and orciprenaline had a similar duration of action and both were longer acting than isoprenaline in the in vivo tests. The ratios found on the tracheal chain preparation are different from those obtained in any in vivo experiment designed to measure airflow or airways resistance in any species tested so far. Thus in vitro tests may give a poor estimate of the real bronchodilator activity of β-stimulants.