Plasma 17-OH corticosteroid measurements were used to evaluate endogenousadrenal function in 23 asthmatic children who were not receiving corticosteroid therapy. When the children were asymptomatic, plasma 17-OH corticosteroid concentrations followed a normal circadian rhythm and were similar in magnitude to those of normal individuals. When the same children had symptoms of asthma, plasma 17-OH corticosteroid concentrations continued to follow the normal circadian pattern and showed only a minute (2 μg per 100 ml.) increase in comparison with control (asymptomatic) values.
The major metabolites identified in the urine after topical administration are salicyluric acid (52%), salicylate glucuronides (42%) and free Salicylic Acid (6%). The urinary metabolites after percutaneous absorption differ from those after oral salicylate administration; those derived from percutaneous absorption contain more salicylate glucuronides and less salicyluric and Salicylic Acid. Almost 95% of a single dose of salicylate is excreted within 24 hours of its entrance into the extracellular space. Fifty to eighty percent of salicylate is protein bound to albumin. Salicylates compete with the binding of several drugs and can modify the action of these drugs. By similar competitive mechanisms other drugs can influence the serum levels of salicylate. (See PRECAUTIONS.)