The In-Vitro Uptake of a Low Dose Drug (Riboflavine) by Some Adsorbents

Abstract

An investigation was carried out of the in-vitro adsorption of a low-dose model drug (riboflavine) by three typzs of kaolin, attapulgite, magnesium trisilicate and a grade of magnesium aluminium silicate (veegum^R. The adsorption experiments were designed under conditions simulating in-vivo with respect to variations in pH values, volume of the adsorption medium, and the presence of electrolytes, a hydrophilic colloid and a surfactant. Under all conditions examined, riboflavine adsorption followed the sequence veegum attapulgite kaolin magnesium trisilicate

The presence of either veegum^R (1 g) or kaolin (4 g) in the medium reduced the level of drug in solution during dissolution rate testing of capsules. Desorption results suggest only partial release of the adsorbed drug. The results obtained emphasiz,e the strong uptake of a potent ionic drug by the various silicates commonly used in pharmacy.