Effect of the biologically active fragment of zonula occludens toxin, ΔG, on the intestinal paracellular transport and oral absorption of mannitol

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International Journal of Pharmaceutics


Objective: Many therapeutically active agents experience low bioavailability upon oral administration due to low permeability, low solubility, interaction with efflux transporters or first pass metabolism. In general, absorption enhancers are agents that can modulate the paracellular permeability of drugs, thus, potentially increasing oral bioavailability. The objective of this study was to examine the effect of the active fragment of Zonula occludens toxin (Zot), ΔG, on the transport of a paracellular marker, mannitol, using in vitro (Caco-2 cell monolayers) and in vivo (intraduodenal administration in rats) experimental methods. Methods: The transport of [14C]mannitol with ΔG (0, 50, 80, or 100 μg/ml) was determined across Caco-2 cells. Male Sprague-Dawley rats were assigned to receive one of the following treatments: [14C] mannitol (40 μCi/kg), [14C]mannitol/ΔG (417 μg/kg), or [14C] mannitol/ΔG/Protease inhibitors (PI). Results: The mean (±S.E.M.) apparent mannitol permeability coefficients (Papp) observed after incubation with 0, 50, 80, and 100 μg/ml ΔG were 3.5 (±0.4), 4.17 (±0.27), 4.33 (±0.61), and 9.94 (±0.24)×10-6 cm/s. After oral administration, Cmax (3.8×10-4 vs. 4.4×10-4 mM) and AUC0-6 h (0.096 vs. 0.088 mM min), obtained for [14C]mannitol and [14C]mannitol/ΔG, respectively, were not statistically different. However, both Cmax (7.6×10-4 mM) and AUC0-6 h (0.25 mM min) were significantly higher for the [14C]mannitol/ΔG/PI treatment. Conclusions: The 12 kDa fragment of Zot, ΔG, enhanced the in vitro transport and oral absorption of the paracellular marker, mannitol, in the presence of protease inhibitors (PI). © 2002 Elsevier Science B.V. All rights reserved.

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