In Vitro Adsorption Studies of Paracetamol to Activated Charcoal Capsule, Powder and Suspension

Introduction: Adsorption capacity of activated charcoal to paracetamol was determined at simulated gastric environment, pH 3.4 and simulated intestinal environment pH 7.2. Three formulations of activated charcoal; powder, capsule and suspension were tested. Paracetamol was derived from tablet to simulate in vivo intoxication conditions. Methods: Activated charcoal and paracetamol were mixed at both the pHs. The amount of activated charcoal was varied to obtain activated charcoal-paracetamol ratio from 10:1 to 1:1. Then the mixtures were shaken, filtered and the content of remaining paracetamol was determined by UV spectrophotometer. Results: The maximal adsorption capacity, milligram of paracetamol adsorbed per gram of activated charcoal, was determined by using Langmuir adsorption isotherm. The maximal adsorption capacity [95% confidence intervals in square brackets] was 284.47 [221.50; 347.44] at pH 3.4 and 303.03 [303.03; 303.03] at pH 7.2 for powder; 175.49 [133.79; 217.18] at pH 3.4 and 213.23 [182.56; 243.90] at pH 7.2 for capsule; and 254.27 [245.08; 263.47] at pH 3.4 and 263.64 [229.13; 298.15] at pH 7.2 for suspension. The effect of pH on adsorption capacity was not significant. Discussion: Under simulated conditions, the three formulations of activated charcoal adsorbed sufficient amount of paracetamol. The data show that activated charcoal 1g/kg body weight is sufficient a poisoned patient from if given shortly after intoxication.