Plasma concentrations of sodium cromoglycate given by nebulisation and metered dose inhalers in patients with exercise-induced asthma: relationship to protective effect.

Plasma sodium cromoglycate (SCG) concentrations were measured in 11 patients at regular intervals before and after exercise in a double-blind study to assess the protective effect in exercise-induced asthma (EIA) of 2, 10 and 20 mg SCG aerosol and placebo, and (on an open basis) nebulised SCG (10 g l-1). There was a dose related increase in plasma concentration and AUC (0-1 h) with the aerosol formulations; values with nebulised SCG were significantly higher than with any aerosol dose. Protection from EIA increased to a maximum of 66% at plasma concentrations of 4 ng ml-1 and above. Thus measurement of plasma concentration can allow a comparison to be made between the protective effects of SCG following different methods of inhalation. It is important to note, however, that plasma concentration per se is almost certainly not related directly to protective effect.