Absorption of labeled triethanolamine salicylate in human and canine knee joints. II.

The transdermal absorption by tissues of salicylate from triethanolamine salicylate (TEA/S) ointment applied to canine and human skin was shown to be consistent, significant, and reproducible. Salicylate levels were measured using thin-layer chromatography, nuclear magnetic resonance, and radiochemistry. Absorption was directly proportional to the concentrations of the active ingredient in the ointment up to the 10 per cent preparation. Tissue salicylate levels were not influenced by the sex of the canine subjects. In humans, the activity of the patients affected both tissue levels and urinary excretion. Autoradiographic and doubly labeled studies suggest that during transdermal absorption of TEA/S, the salt may disassociate; this could permit the salicylate to have a longer transit time in the area of application.