The Effect of trans-4-Guanidinomethylcyclohexanecarboxylic Acid p-tert-Butylphenyl Ester Hydrochloride (NCO-650) on Ascaris suum Antigen-Induced Bronchoconstriction in Dogs

Antiallergic asthma effect of trans-4-guanidinomethylcyclohexane-carboxylic acid p-tert-butylphenyl ester hydrochloride (NCO-650), a new antiallergic drug, was investigated in comparison with those of tranilast and disodium cromoglycate (DSCG) in anesthetized dogs. The asthmatic bronchoconstriction was induced by inhalation of Ascaris suum antigen (Asc-Ag) to naturally Ascarissensitive dogs. The airway resistance was determined using the modified KonzettRössler method. Both intravenous (1 and 5 mg/kg) and intraduodenal (10, 30 and 100 mg/kg) administrations of NCO-650 prior to the antigen challenge markedly inhibited the asthmatic bronchoconstriction induced by Asc-Ag inhalation. The antiasthmatic effect of NCO-650 was much stronger than that of DSCG (10 mg/kg, i.v.) and was about three-fold stronger than that of tranilast. On the other hand, when NCO-650 was administered after the antigen challenge, the agent had no inhibitory effect on the Asc-Ag induced bronchoconstriction. As for the effects on increased airway secretion at the time of asthmatic attack, NCO-650 inhibited the excessive secretions without any remarkable change in the viscosity of the secretions. NCO-650 had no effect on the bronchoconstriction induced by inhalation of acetylcholine, suggesting that NCO-650 appears to have no anticholinergic effect and thus no effect on the vagal reflex that occurred during the asthmatic responses. The above findings show that NCO-650 may be useful for the treatment of bronchial asthma as an orally active drug.