Transport mechanisms of nicotine across the human intestinal epithelial cell line Caco-2

Ulcerative colitis is a disease more commonly seen in nonsmokers. Because nicotine was postulated to be a beneficial component of tobacco smoke for ulcerative colitis, various formulations of nicotine have been developed to improve the local bioavailability within the gastrointestinal tissue. In the present study, to characterize the disposition of nicotine in the intestines, we investigated intestinal nicotine transport using Caco-2 cells. Nicotine was predominantly transported across Caco-2 cell monolayers in a unidirectional mode, corresponding to intestinal secretion, by pH-dependent specific transport systems. The specific uptake systems appear to be distinct from organic cation transporters and the transport system for tertiary amines, in terms of its substrate specificity and the pattern of the interaction. These transport systems could play a role in the intestinal accumulation of nicotine from plasma and could also be responsible for the topical delivery of nicotine for ulcerative colitis therapy. These findings could provide useful information for the design of effective nicotine delivery.