Respirable form of crystals of cromoglycic acid.

Respirable crystals of cromoglycic acid (CA) were prepared by precipitation of CA with hydrochloric acid from aqueous solutions of cromolyn sodium and subsequent recrystallization from hot water or mixtures of dimethyl sulphoxide and water. The properties of the materials were established by melting point measurements, UV, IR, and NMR spectroscopy, and X-ray diffraction. Aerosols of CA were generated by nebulization of dilute CA suspensions and drying. The aerodynamic size distribution of CA in the dried aerosols was found by cascade impaction, and could be characterized by a logarithmic normal function with a mass median aerodynamic diameter (MMAD) of 0.7 micron and geometric standard deviation (sigma g) of 1.9. The likely advantages and problems of CA aerosols in the prevention of asthma are discussed.