(W1130-03-15) A Biorelevant In Vitro Methodology for Assessing the Efficiency and Safety of Activated Charcoal in the Management of Drug-Induced Intestinal Dysbiosis

Purpose: Oral administration of activated charcoal (AC) for the physical elimination of unabsorbed moxifloxacin (MXF) from the colonic lumen has been shown to be efficacious and safe at the clinical level [de Gunzburg et al. 2014; de Gunzburg et al. 2018]. Efficiency of the approach in clinical practice, however, may be limited by patient’s compliance to receiving the required dosing regimen. This work had four objectives: 1. Apply a biorelevant in vitro methodology for the assessment of efficacy of AC to eliminate unabsorbed MXF from the colonic lumen, and evaluate its usefulness, based on published clinical data. 2. Apply the same in vitro methodology for assessing the AC efficacy to eliminate unabsorbed rosuvastatin (RSV) from the colonic lumen. As with MXF, RSV accumulates in the colon primarily due to extensive enterohepatic circulation, it is found in feces and it has been associated with intestinal dysbiosis. 3. Evaluate the efficiency of AC to eliminate MXF vs. RSV from the colonic lumen. 4. Evaluate safety issues, based on the impact of AC on osmolality of sodium chloride solutions with biorelevant osmolality values.

Methods: The AC efficacy in removing MXF and RSV from biorelevant media, i.e., Level II FaSSCoF and Level II FeSSCoF [Markopoulos, Andreas et al. 2015] was evaluated by using- Two types of AC (Filtercarb PCC-F and Filtercarb Pharma-A, Carbonitalia S.r.l., Livorno, Italy), moxifloxacin HCl and rosuvastatin calcium. Biorelevant MXF concentration (3.3 mg/mL) and RSV concentration (1 mg/mL), based on the MXF and RSV amounts excreted in feces, the aqueous MXF and RSV solubility, and the water content of the lower intestine, and AC/MXF (w/w) ratios of 1, 2, 3, 5, 7 and 10 and AC/RSV (w/w) ratios of 1, 2, 3, 5, 7, 10, 20 and 30. Adsorption experiments (in triplicate) lasted for 4h with Filtercarb PCC-F and for 2h with Filtercarb Pharma-A, based on the equilibration times estimated in Level II FaSSCoF and in Level II FeSSCoF. MXF was quantified by applying a previously developed HPLC-UV method [Djurdjevic et al. 2009] with modifications (LOQ 0.05 µg/mL) and RSV was quantified by applying a previously developed HPLC-UV method [Kumar et al 2008] with modifications (LOQ 0.01 µg/mL). Osmolality of sodium chloride solutions used to evaluate the impact of AC on electrolyte balance ranged from 100 mOsm/kg to 293 mOsm/kg.

Results: For both types of AC investigated in this study, physiological variation of pH and/or colloidal species was found to affect the adsorption of MXF and RSV onto AC. For both drugs, the type of AC impacted substantially the adsorption capacity. When using Filtercarb PCC-F, complete removal of MXF and RSV was observed at AC/drug (w/w) ratios of 10 and 20, respectively. Corresponding ratios when using Filtercarb Pharma-A were 5 and 7. Considering the volume of contents of the lower intestine, in vitro MXF data with Filtercarb Pharma-A were in line with published clinical MXF data [de Gunzburg et al 2018]. The comparatively higher amounts of moxifloxacin accumulating in the colon suggests that the approach would be more efficient for rosuvastatin removal. Osmolality of sodium chloride solutions was not decreased, suggesting no impact of AC at the selected working AC amounts/volume in the present investigation, in line with the lack of significant adverse effects or relevant amounts of AC in humans [de Gunzburg et al. 2018].

Conclusion: The type of AC and the amount of drug that reaches the lower intestine after single dosing seem to be the most critical variables that determine the efficiency of AC in managing drug-induced intestinal dysbiosis. It would be interesting to confirm these findings in physiologically more relevant media, e.g optimized fecal material [Vertzoni et al. 2018]. In line with published clinical data this study suggests ionic balance in the colonic lumen is unlikely to be affected by AC amounts which could be considered for removal of unabsorbed drugs.

References: de Gunzburg et al. J Clin. Pharmacol. 2014; 55:10-16
de Gunzburg et al. J Infect Dis. 2018; 217:628-636.
Djurdjevic et al. J Pharm Biomed Anal. 2009; 50:117-126.
Kumar et a.l Biomed Chromatogr. 2006; 20:881-887
Markopoulos, Andreas et al. Eur J Pharm Biopharm. 2015; 93:173-82.
Vertzoni et al. Eur J Pharm Sci. 2018; 125:142-150.

Acknowledgements: Part of this work was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 956851.