Protective effect of disodium cromoglycate against airway constriction induced by hemp dust extract

Abstract

The effect of disodium cromoglycate (DSCG) was studied in 14 healthy subjects following hemp dust extract (HDE) inhalation (10-min exposure). Ten subjects were given 20 mg of DSCG or a placebo and then challenged with dust aerosol at 30 min post-DSCG inhalation. Partial expiratory flow-volume (PEFV) curves were recorded at least 30 min after exposure, and maximum expiratory flow rates at 40% of the control vital capacity [MEF40%(P)] were read from these curves. Significant acute reductions in MEF40%(P) were recorded after HDE alone and after pretreatment with placebo (p < 0.01). There was considerable protection from a single dose of 20 mg of DSCG against hemp-induced bronchoconstriction although the acute reductions in MEF40%(P) were still statistically significant at 20 and 30 min postexposure. A group of 7 subjects was given 40 mg of DSCG or placebo 30 min prior to HDE inhalation. In another experiment this group was given 20 mg of DSCG four times daily for 2 days, and on the third day challenged with HDE. The protective effect of DSCG is a short-term one: somewhat less protection was seen after 2 days of four times 20 mg of DSCG/day than 30 min after a single dose of 40 mg. Measurement of airway conductance (Gaw) in 6 subjects demonstrated prevention of acute reductions in Gaw at low lung volumes (25% VC) in 4 out of 6 subjects. We suggest that inhalation of 40 mg of DSCG prior to a work shift might be considered as a temporary means of protecting textile workers against the constrictor effects of dust in their work.