CONTEXT: Intoxications with gamma-hydroxybutyrate (GHB) are occurring more frequently. Patients are primarily treated symptomatically. The use of activated charcoal (AC) has been suggested in several guidelines and in literature, although the clinical value of AC in GHB intoxication is a matter of debate. However, it has never been demonstrated that GHB binds to AC. Under certain conditions, prevention of absorption could be clinically relevant. Therefore, adsorption of GHB to AC in an in vitro model was tested. MATERIALS AND METHODS: A previously described in vitro model was used. Dosages of 2.5, 5, 7.5, or 10 g of standard AC (simulating in vivo dosages of approximately 25-100 g) were mixed with a dose of 800 mg GHB at 37 °C in 100 mL simulated gastric or intestinal fluid, respectively. Subsequently, the AC was separated from the liquid by centrifugation and the remaining GHB quantified by gas chromatography. GHB adsorption capacity was plotted in an adsorption curve. RESULTS: Binding of GHB to AC was dose-dependent. At gastric pH, adsorption was higher than at intestinal pH, with a maximum adsorption of 84.3% and 23.3%, respectively, with 10 g of AC, corresponding with a high adult dose. DISCUSSION AND CONCLUSION: AC has clinically relevant GHB binding capacity, which is pH dependent. The normally rapid adsorption and the need for intubation argue against AC treatment in GHB intoxications. However, under certain circumstances e.g. in case of unintentional intake of GHB by children or in case of very high doses of GHB, rapid treatment with AC may still be appropriate. In vivo studies are needed to establish the clinical relevance of GHB adsorption to AC.
CONTEXT: Intoxications with gamma-hydroxybutyrate (GHB) are occurring more frequently. Patients are primarily treated symptomatically. The use of activated charcoal (AC) has been suggested in several guidelines and in literature, although the clinical value of AC in GHB intoxication is a matter of debate. However, it has never been demonstrated that GHB binds to AC. Under certain conditions, prevention of absorption could be clinically relevant. Therefore, adsorption of GHB to AC in an in vitro model was tested. MATERIALS AND METHODS: A previously described in vitro model was used. Dosages of 2.5, 5, 7.5, or 10 g of standard AC (simulating in vivo dosages of approximately 25-100 g) were mixed with a dose of 800 mg GHB at 37 °C in 100 mL simulated gastric or intestinal fluid, respectively. Subsequently, the AC was separated from the liquid by centrifugation and the remaining GHB quantified by gas chromatography. GHB adsorption capacity was plotted in an adsorption curve. RESULTS: Binding of GHB to AC was dose-dependent. At gastric pH, adsorption was higher than at intestinal pH, with a maximum adsorption of 84.3% and 23.3%, respectively, with 10 g of AC, corresponding with a high adult dose. DISCUSSION AND CONCLUSION:AC has clinically relevant GHB binding capacity, which is pH dependent. The normally rapid adsorption and the need for intubation argue against AC treatment in GHB intoxications. However, under certain circumstances e.g. in case of unintentional intake of GHB by children or in case of very high doses of GHB, rapid treatment with AC may still be appropriate. In vivo studies are needed to establish the clinical relevance of GHB adsorption to AC.