Prediction of adsorption from multicomponent solutions by activated carbon using single-solute parameters

Area of Science:

• Pharmacokinetics
• Materials Science
• Analytical Chemistry

Background:

• Activated carbon is widely used for drug adsorption.
• Understanding multicomponent adsorption is crucial for drug formulation and delivery.
• Barbiturates are a class of drugs with varying physicochemical properties.

Purpose of the Study:

• To investigate the adsorption of three barbiturates (phenobarbital, mephobarbital, primidone) onto activated carbon from simulated intestinal fluid.
• To evaluate the performance of different competitive adsorption models in predicting multicomponent adsorption isotherms.
• To assess the utility of single-solute isotherm parameters for predicting multicomponent adsorption behavior.

Main Methods:

• Adsorption studies were conducted using the rotating bottle method with activated carbon and simulated intestinal fluid.
• Drug concentrations were quantified using high-performance liquid chromatography (HPLC) with a reversed-phase column.
• Data were fitted to the competitive Langmuir-like, modified competitive Langmuir-like, and LeVan-Vermeulen models.

Main Results:

• The modified competitive Langmuir-like and LeVan-Vermeulen models demonstrated excellent agreement with experimental data.
• The original competitive Langmuir-like model showed less satisfactory agreement, likely due to its assumption of equal adsorbate capacities.
• Results indicate that the barbiturates compete for the same binding sites on the activated carbon surface.

Conclusions:

• Accurate prediction of multicomponent adsorption isotherms is achievable using single-solute isotherm parameters.
• The modified competitive Langmuir-like and LeVan-Vermeulen models are suitable for describing barbiturate adsorption on activated carbon.
• These findings can enhance in vitro/in vivo correlations for drug absorption and formulation.