Kinetics of decomposition and formulation of hydrocortisone butyrate in semiaqueous and gel systems

Article abstract of DOI:10.1002/jps.2600720715

The stability of hydrocortisone butyrate in semiaqueous and formulated gel systems has been investigated. It was shown that hydrocortisone butyrate underwent reversible isomerization to the C-21 ester of butyric acid. This ester then hydrolyzed to hydrocortisone, which in turn degraded to a complex mixture of compounds. This step is metal catalyzed and can be inhibited by the addition of EDTA [disodium(ethylenedinitrilo)tetraacetate]. The kinetics of decomposition is modeled using nonlinear regression analysis, and the rate constants for the various decomposition pathways are quantified.