title: Kinetics of decomposition and formulation of hydrocortisone butyrate in semiaqueous and gel systems.
abstract: 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.
mesh_terms: D004355:Drug Stability; D004356:Drug Storage; D005782:Gels; D006854:Hydrocortisone / Q000031:analogs & derivatives*; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D007700:Kinetics; D012996:Solutions; D013997:Time Factors
chemical_list: D005782:Gels; D012996:Solutions; C007975:hydrocortisone-17-butyrate; D006854:Hydrocortisone