Effect of ethanol and pH on the in vitro adsorption of diazepam onto activated charcoal from simulated gastric fluid and simulated intestinal fluid

Diazepam ingestion along with ethanol is encountered commonly in drug overdose cases. In the present study, the effect of pH and ethanol on the adsorption of diazepam in the simulated gastric fluid and the simulated intestinal fluid onto activated charcoal was determined in vitro. The adsorption behaviors of diazepam in both simulated gastric and intestinal pH onto activated charcoal were studied. In the adsorption study with ethanol, some of the gastric or intestinal fluid was replaced with an equivalent volume of 10 and 25% ethanol, respectively. The unabsorbed diazepam in simulated gastric fluid and simulated intestinal fluid (with and without ethanol) was determined by UV spectrophotometer at wavelengths 289 and 256 nm, respectively. The maximum adsorption capacities (at 95% confidence limits) of activated charcoal were 25 (18.42; 31.5) mg and 200 (175.158; 224.84) mg diazepam/g activated charcoal at pH values 1.2 and 6.8, respectively. In case of 10 and 25% ethanol, adsorption in the simulated gastric fluid were 19.20 (21.23; 18.00) and 0.268 (0.286; 0.26), respectively. Surprisingly, in the simulated intestinal fluid, the adsorption patterns were not affected due to presence of 10% ethanol while it was reduced to 76.92 (78.179; 74.84) mg at 25% ethanol concentration. Under the simulated gastrointestinal environmental condition, the activated charcoal adsorbed a sufficient amount of diazepam (200 mg/g-25 mg/g) with maximum at intestinal pH. Our results show that standard dose of 50 g of activated charcoal as provided in general poisoning cases is sufficient to prevent diazepam intoxication with or without ethanol