标题：TA-2005, a Novel, Long-Acting, and Selective β2-Adrenoceptor Agonist : Characterization of Its in Vivo Bronchodilating Action in Guinea Pigs and Cats in Comparison with Other β2-Agonists
摘要：Relaxant effects of the β2-selective adrenoceptor agonist TA-2005 on bronchoconstriction in the anesthetized guinea pig and cat were evaluated in comparison with other known β2-adrenoceptor agonists. The ED50 values of intravenously administered TA-2005, procaterol, formoterol, isoproterenol, salbutamol, and salmeterol to inhibit the histamine-induced bronchoconstriction of the guinea pigs were 0.024, 0.053, 0.056, 0.099, 0.23, and 2.00μg/kg, respectively, and those in serotonin-challenged cats were 0.019, 0.037, 0.039, 0.042, 0.13, and 0.52μg/kg, respectively, in the same increasing order. When guinea pigs were passively sensitized with anti-ovalbumin antiserum, the ED50 values of TA-2005, formoterol, procaterol, and isoproterenol to inhibit the antigen-induced bronchoconstriction were 0.09, 0.30, 0.65, and 7.0μg/kg, i.v., respectively, while those of TA-2005, procaterol, formoterol, and salbutamol in actively sensitized animals were 0.24, 0.25, 1.40, and 23.0μg/kg. When TA-2005 was administered by inhalation to guinea pigs or by the intraduodenal route to cats, it exhibited a long-lasting inhibitory effect comparable or superior to the effects of salmeterol and formoterol. These data indicate that, among the known β2-adrenoceptor agonists examined, TA-2005 exerts the most potent bronchodilating effects with a long duration of action in vivo, and its potency ratios to the other reference drugs were greater in antigen-than spasmogen-induced bronchoconstric-tion models.
