Measurement of intestinal charcoal transit ratio

Gastrointestinal propulsion of a charcoal meal was measured according as described by Sagar et al. [49] with slight modifications. Test animals were fasted 18 h prior to the experiment. Ten minutes after the last dose of the test compound (sixth day of administration), the animals from each group were fed 1 ml of a charcoal meal containing 3% suspension of activated charcoal in 0.5% aqueous methylcellulose (Sigma-Aldrich Co. Ltd., St. Louise, MO, USA). Thirty minutes after administration of the charcoal meal, 99.0% CO₂ gas as a euthanasia agent was used, for euthanasia of rodents [50] and the animals were sacrificed via cervical dislocation. The intestinal charcoal transit ratio was estimated following the Eq. 3.