Impact of Drug Nature and Solvent Type on Charcoal Adsorption Efficiency

Nova Southeastern University, Davie, Florida, USA

Objective: Investigate the effects of the ionic nature of the drug and the type of solvent on the adsorption efficiency of charcoal. Background: Activated charcoal is widely used as a detoxifying agent for its efficient adsorption of various molecules. In this study, we evaluated the effect of the drug ionic nature and the effect of solvent type on the charcoal’s adsorption efficiency. Methods: Cationic dextromethorphan HBr, anionic diclofenac sodium, and non-ionic acetaminophen were separately mixed with charcoal (1:8 ratio) in 10 mL different solvents. The samples were centrifuged, and the supernatant was analyzed for drug content (UV-Vis spectroscopy). The % of the adsorbed drug was calculated from mass balance. The sediment was analyzed (DSC, 25–350 °C @ 10 °C/min.) to confirm the drug adsorption onto charcoal. Results: >90% drug adsorption in HCl. The results in the other solvents varied among the drug molecules. For dextromethorphan, >90% adsorption in saline and NaHCO3, ~70–80% in water and vinegar, and ~40% in 40% ethanol. For diclofenac, >90% adsorption in water and vinegar, ~70% in ethanol and saline, and minimal adsorption (6%) in NaHCO3. For acetaminophen, >90% adsorption in water, ethanol, and NaHCO3, ~80% in vinegar, and ~40% in saline. The DSC results confirmed the drugs’ adsorption on the charcoal. Conclusion: Charcoal has in general an effective adsorption capacity in water and acidic solutions for all drugs regardless of their nature. The charcoal adsorption capacity in other solvents is affected by other drug properties (e.g., lipophilicity). Grants: NSU Grant 335081.