Evaluation of absorption enhancement for a potent cyclopeptidic alpha(nu)beta(3)-antagonist in a human intestinal cell line (Caco-2)

Different absorption enhancing principles for a potent cyclopeptidic alpha( nu)beta(3)-antagonist (EMD 121974) were investigated in monolayers of a hum an intestinal cell line (Caco-2). Transepithelial transport was quantitated by reversed-phase high-performance Liquid chromatography. Cytotoxic effect s were characterized by determination of transepithelial electrical resista nces (TEERs), propidium iodide (PI)-influx, FITC-phalloidin staining and th e release of cytosolic lactate dehydrogenase (LDH). Medium chain fatty acid s (MCFAs, NaC10, NaC12) and taurocholate (NaTC) were the most efficient enh ancers of cyclopeptide and FITC-dextran 4400 permeability coefficients, dis playing different time profiles of activity. Whereas NaTC (15 mM) showed al most a constant permeation enhancing effect from 20 min up to 120 min (ca. 12-fold), MCFA absorption enhancement was markedly dependent on incubation time (NaC10, 20 min: 1.2-fold, 120 min: 17-fold; NaC12, 20 min: 4.3-fold, 1 20 min: 13-fold). All cytotoxicity assays demonstrated that MCFAs were sign ificantly more cytotoxic than NaTC. Ion pairing with hydrophobic amino acid s and heptane sulfonate distinctly increased octanol-buffer partition coeff icients of the cationic cyclopeptide but did not enhance its transepithelia l permeability. Nanoparticles as well as beta-cyclodextrin neither affected integrity of the cells nor transport properties of the cyclopeptide. In su mmary, significant absorption enhancement was only observed with NaTC or MC FAs. Increase in permeability coefficients using NaTC occurred rapidly with acceptable cytotoxicities and merits further investigations. (C) 2000 Else vier Science B.V. All rights reserved.