Influence of Internal Structure of the Sorbents on Diazepam Sorption from Simulated Intestinal Fluid

Abstract

The capacity of natural Na-montmorillonite and activated charcoal for sorption of diazepam from simulated intestinal fluid (SIF) was studied. The main characteristics of the sorbents were determined. In order to characterize the sorption process of diazepam the influence of the pH, contact time and ethanol presence in SIF was analyzed. Adsorption isotherms for the diazepam-activated charcoal and diazepam-natural Na-montmorillonite systems were determined. The Langmuir isotherm model provided a very good description of diazepam sorption. Furthermore, the pH-drift method was used to determine the specific pH at zero point of charge (pHzpc) of the sorbents. The obtained results show that the internal structure of the sorbents and pH of the SIF solutions are very important for diazepam sorption. Both the surface of the activated charcoal and natural Na-montmorillonite are positively charged below the pHzpc so the sorption of diazepam is higher below this point and occur by van der Waals forces. The presence of ethanol in simulated intestinal fluid lowers the adsorption of diazepam on both sorbents.

Kinetic adsorption of drugs using carbon nanofibers in simulated gastric and intestinal fluids

“…have studied the influence of internal structure of the adsorbents on diazepam adsorption in simulated intestinal fluid (SIF) and reported the higher adsorption capacity of activated carbon than mineral clay since the activated carbon has a pore volume which is much higher than the one of the mineral clay. Another important result is the uptake of diazepam by both adsorbents decreases in the presence of ethanol 4 . Regmi et al.…”

“…Another important result is the uptake of diazepam by both adsorbents decreases in the presence of ethanol. 4 Regmi et al have reported in vitro adsorption of dextromethorphan syrup which is an over-the-counter antitussive drug using activated charcoal in simulated gastric and intestinal fluids. They have showed that the use of activated charcoal might be the most effective approach for the dextromethorphan overdose treatment.…”