The relevance of the rat single-pass intestinal perfusion model for investigating) of six model compounds, and the blood-to-lumen clearance of Cr-EDTA (CL and CL (maximum and total) during the perfusion experiments were dependent on exposure time (15 and 60 min), and the concentration of SDS, but not chitosan. The increases in J and CL following the 15-min intestinal exposure of both SDS and chitosan were greater than those reported from an rat intraintestinal bolus model. However, the effect in the bolus model could be predicted from the increase of J at the end of the 15-min exposure period, where a six-fold increase in J was required for a corresponding effect in the bolus model. This illustrates that a rapid and robust effect of the AME is crucial to increase the Cr-EDTA, as J for the drugs was more sensitive than CL at detecting dynamic mucosal AME effects, such as response rate and recovery. Finally, there appears to be no nicotinergic neural contribution to the absorption-enhancing effect of SDS and chitosan, as luminal administration of 0.1 mM mecamylamine had no effect.