Dissolution of Hydrocortisone in Human and Simulated Intestinal Fluids

Purpose. To compare solubility and dissolution rate of hydrocortisonein aspirated human intestinal fluids (HIFs) with simulated intestinalfluids (SIFs) and buffer.Methods. Solubility and flux from a rotating disk of hydrocortisonewere measured. The bile salt content, pH and osmotic pressure weredetermined in HIFs.Results. In fasted state the solubility of hydrocortisone was higher inHIFs than in the buffer and SIFs. The flux of hydrocortisone in HIFswas similar to the flux in the buffer but lower than the flux in SIFs atfasted state. Addition of intestinal surfactants in SIFs increasedsolubility and flux at both fasted and fed state. The increase in solubility wascaused by micelle formation in SIFs. The increase in flux may partlybe explained by increased solubility. The bile salt content of the HIFsdid not correlate with the solubility or the flux but pH in the HIFsseems to have some effect on the components of the HIFs resultingin increased solubility.Conclusions. It is possible to perform comparable dissolution tests inHIFs and SIFs. The lack of correlation between the results in HIFs andthe bile salt content may be explained by the relatively low lipofilicity ofthe model drug.