Preliminary investigations into the in-vitro interaction of folic acid with magnesium trisilicate and edible clay

Abstract

The in vitro interaction between folic acid and magnesium trisilicate as well as edible clay was studied. Folic acid was significantly adsorbed onto the absorbents from both water and 0.01 M HCl at 37 ° C. The adsorption of the drug onto magnesium trisilicate from distilled water obeyed the Langmuir relationship while that from 0.01 M HC1 was biphasic. The adsorption of folic acid onto the clay was affected by the inclusion of sodium chloride (NaCl) and followed the rank order: edible clay + 7.5% w/w NaCl ⪢ edible clay + 5.0% w/w NaCl ⪢ edible clay + 10.0% w/w NaCI ⪢ unsalted edible clay. Complete desorption of folic acid from the adsorbents by digestion in water, 0.01 M HCl or 0.1 M HCl was not achieved. This is an indication that adsorption was facilitated by the presence of strong chemical bonds. Dissolution of folic acid from tablets in the presence of the adsorbents was retarded due to the adsorption of the drug onto the adsorbents.