Adsorption of certain oral hypoglycaemics on kaolin and charcoal and its relationship to hypoglycaemic effects of drugs

The adsorption of acetohexamide, tolazamide and tolbutamide at pH 7.4 on kaolin and activated charcoal was studied at 37°C. Langmuir adsorption isotherms were established and the maximum adsorption capacities of activated charcoal and kaolin were estimated. The results of desorption experiments suggested that desorption was incomplete, but to a relatively greater extent from activated charcoal than from kaolin. The hypoglycaemic activity of the 3 drugs was suppressed in the presence of both activated charcoal or kaolin.