In vitro investigations of α-amylase mediated hydrolysis of cyclodextrins in the presence of ibuprofen, flurbiprofen, or benzo[a]pyrene

In vitro studies of alpha-amylase degradation of alpha-, beta- and gamma-cyclodextrins and 2-hydroxypropyl-beta- and -gamma-cyclodextrins were investigated spectrophotometrically by measuring the formation of reducing sugars, the reaction products of alpha-amylase degradation. This was done to evaluate potential degradation and thereby biological conversion of the cyclodextrins if dosed orally, as the intestinal tract contains alpha-amylase for digestive purposes. The results demonstrated that only gamma- and 2-hydroxypropyl-gamma-cyclodextrins can be degraded by alpha-amylase to a relevant extent, that is, gamma- and 2-hydroxypropyl-gamma-cyclodextrins have different biopharmaceutical behaviours than the other evaluated cyclodextrins. The rate of degradation was affected by the addition of the inclusion complex forming additives flurbiprofen, ibuprofen and benzo[a]pyrene. This effect between the degradation dynamics and the included additives was caused by a correlation between solubility of the additives and the stability of the complex. (C) 2012 Elsevier Ltd. All rights reserved.