title: Comparison of the adsorption capacities of an activated-charcoal--yogurt mixture versus activated-charcoal--water slurry in vivo and in vitro.
abstract: BACKGROUND
  An activated charcoal--yogurt mixture was evaluated in vivo to determine the effect on the gastrointestinal absorption of paracetamol, as compared to activated-charcoal--water slurry. The potential advantage of the activated-charcoal--yogurt mixture is a better palatability and general acceptance by the patients without loss of efficacy. In addition, paracetamol adsorption studies were carried out in vitro to calculate the maximum adsorption capacity of paracetamol to activated-charcoal--yogurt mixture.
  
  
  METHODS
  In vivo: A randomized crossover study on 15 adult volunteers, using paracetamol 50 mg/kg as a simulated overdose. Each study day volunteers were given a standard meal 1 h before paracetamol, then 50 g activated charcoal 1 h later in either of two preparations: standard water slurry or mixed with 400 mL yogurt. Paracetamol serum concentrations were measured using HPLC. The areas under the concentration-time curve (AUC) of the two preparations were compared and used to estimate the efficacy of each preparation. The palatability of both preparations was evaluated using a visual-analogue scale where the volunteers were asked to evaluate the appearance, smell, flavor, texture, ability to swallow, and overall impression of the mixtures. The time spent to consume the activated charcoal was also registered. In vitro: Activated charcoal, simulated gastric (pH 1.2) or intestinal (pH 7.2) fluid, and paracetamol were mixed with yogurt followed by 1 h incubation. The maximum adsorption capacity of paracetamol to activated charcoal was calculated using Langmuir's adsorption isotherm. Paracetamol concentration was analyzed using HPLC.
  
  
  RESULTS
  In vivo there was no significant difference (p > 0.05) in the AUC of paracetamol between the two activated-charcoal preparations. Geometric mean values and 95% CI for the AUCs were (in mg/l x min): 6307 (4932-8065) for the activated charcoal--water slurry and 6525 (5111-8330) for the activated charcoal--yogurt mixture. The palatability study showed significant difference (p < 0.05) only in duration of administration, in favor of the activated charcoal--water slurry. In vitro the maximum adsorption capacity of activated charcoal with added yogurt was 544 mg paracetamol/g activated charcoal (pH 1.2), and 569 mg paracetamol/g activated charcoal (pH 7.2).
  
  
  CONCLUSIONS
  The two activated-charcoal preparations showed equal (NS) absorption reduction of paracetamol in vivo. Mixing activated charcoal with yogurt rather than water prolonged the ingestion time, but did not improve the palatability in adults. The presence of yogurt reduced the adsorption capacity in vitro by 9-13% (p < 0.05) compared to control without yogurt (previous study with the same setup).
authors: Department of Clinical Biochemistry, Bispebjerg Hospital, Copenhagen, Denmark. lottehoegberg@sol.dk
authors: Lotte Christine Groth
authors: LC
authors: Hoegberg
authors: Anne-Bolette
authors: AB
authors: Christophersen
authors: Hanne Rolighed
authors: HR
authors: Christensen
authors: Helle Riis
authors: HR
authors: Angelo
mesh_terms: D000082:Acetaminophen / Q000008:administration & dosage / Q000493:pharmacokinetics; D000327:Adsorption; D000328:Adult; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000493:pharmacokinetics; D000931:Antidotes / Q000008:administration & dosage* / Q000494:pharmacology*; D019540:Area Under Curve; D002606:Charcoal / Q000008:administration & dosage* / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D013056:Spectrophotometry, Ultraviolet; D013649:Taste; D014867:Water; D015014:Yogurt
chemical_list: D018712:Analgesics, Non-Narcotic; D000931:Antidotes; D014867:Water; D002606:Charcoal; D000082:Acetaminophen