Bronchospasm Induced by Inhalation of Substance P: Effect of Sodium Cromoglycate

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Abstract
The aim of this study was to evaluate in vivo the effect of inhaled substance P (SP) and to determine the effect of sodium cromoglycate (SCG) on bronchospasm induced by its inhalation in 6 asthmatic patients. At the beginning of the study, all patients were asymptomatic, with an FEV1 value not less than 20%. SP was administered as aerosol, prepared in 0.9% saline to produce a dose range of 0.03–1 mg. Airway response was measured as FEV1 using a pulmonary system 47120A Hewlett-Packard instrument. The dose of SP producing a 20% change in FEV1 was calculated from the individual semi-logarithmic dose-response curve (PD20). After administration of the placebo, SP produced a dose-related bronchoconstriction with a geometric mean PD20 of 0.15 mg. After SCG, the mean PD20 value was of 0.64 mg (p < 0.01). These results confirmed the bronchospasm induced by inhalation of SP and demonstrated that SCG is able to prevent this effect although it is impossible to define the exact mechanism of the drug.