Glucocorticoid receptor-ligand binding kinetics of budesonide, a glucocorticoid used for inhalation therapy, were determined and compared with dexamethasone and fluticasone propionate using glucocorticoid receptors from human lung tissue. From the association constant of 18.9 x 10(5)l mol-1 min-1 and the dissociation constant of 25.0 x 10(-4) min-1 resulted the equilibrium dissociation constant KD of 1.32 nmol/l and a relative receptor affinity of 855 with dexamethasone as reference (100). The half-life of the budesonide-receptor complex was 4.6 h. Results agree with data derived from competition tests we performed earlier.