[Radioimmunologic detection of triamcinolone-acetonide and its application in a study on the hydrolysis of water soluble corticoid esters].

The rate of hydrolysis of different water soluble esters of corticoids was determined with newly developed specific radioimmunoassays in healthy subjects. It can be found, that triamcinoloneacetonide phosphate was significantly faster transformed into free form after i.v. application than the reference substances prednisolone- and methylprednisolone hemisuccinate. Moreover the plasma concentration of free triamcinolone-acetonide decreases much faster than that of free prednisolone and methylprednisolone. This shows, that triamcinoloneacetonide is distributed wider and very quickly, probably in the intracellular fluid volume. At this time it is not clear, whether only free steroids are biologically active or the water soluble derivatives as well. Our results can be of clinical importance because of the different rates of hydrolysis as well as of differences in the diffusion.