The pharmacokinetic assessment of sodium cromoglycate.

The plasma concentration of sodium cromoglycate (SCG) was measured in four healthy subjects by radioimmunoassay after a 4 mg intravenous dose and after inhaling from 20 mg capsules, and from 10 and 30 mg ml-1 nebulizer solutions. The mean absorption constant (K1) after inhalation was 0.43 h-1. The mean elimination constant from the plasma (Kelim) after intravenous administration was 11.5 h-1, and that after inhalation was similar. The apparent volume of distribution of SCG (Vd beta) was 0.2 litre kg-1 and the mean plasma clearance was 0.35 litre h-1kg-1. The amount of SCG absorbed after inhalation varied according to the method of inhalation and dose. After the inhalation of powder from 20 mg capsules, 1.30-3.96 mg reached the plasma, after inhalation of SCG produced by nebulizing a 10 mg ml-1 solution for 5 min at 10 psi using a Minineb nebulizer 0.19-0.31 mg reached the plasma and when the solution was increased to 30 mg ml-1 the figure was 0.33-0.45 mg.