[Effects of inhaled SDZ ISQ 844, a cyclic nucleotide phosphodiesterase isoenzyme type III/IV inhibitor, on airway responsiveness in beagles].

To evaluate the effects of inhaled SDZ ISQ 844, a selective cyclic nucleotide phosphodiesterase (PDE) isoenzyme type III/IV inhibitor and inhaled salbutamol on airway responsiveness, we studied the changes in airway responsiveness following inhalation of SDZ ISQ 844 and salbutamol in 7 beagles. Respiratory resistance and airway responsiveness to inhaled methacholine were determined by modified Astograph (7 Hz oscillation method), SDZ ISQ 844 solution (5 x 10(-4) M) and salbutamol solution (5 x 10(-5) M) were delivered as aerosols generated from a Bird nebulizer for ten minutes. After inhalation of salbutamol respiratory resistance showed a slight but significant decrease (p < 0.05). Inhaled SDZ ISQ 844 did not affect respiratory resistance. Airway responsiveness decreased significantly following inhalation of SDZ ISQ 844 and salbutamol (p < 0.02). There was no significant difference between the changes in airway responsiveness following the inhalation of SDZ ISQ 844 and salbutamol. These results indicate that inhalational administration of a selective PDE isoenzyme type III/IV inhibitor, SDZ ISQ 844 decreases airway responsiveness at dosage which does not affect the base-line respiratory resistance.