The purpose of this study was to estimate the effect of the anionic surfactant sodium dodecyl sulphate (SDS) on the permeability and dissolution of fexofenadine hydrochloride (FEX) and the transepithelial electrical resistance (TEER) with Caco-2 cells. The dissolution profile of FEX was evaluated at different pH values (1.2, 3.2, 4.2, 4.5, 5.2 and 6.8) at 37 +/- 0.5 degrees C and chracterized in presence of SDS. The dissolution of FEX was increased in the presence of SDS. For permeability studies, apical to basolateral and basolateral to apical permeability was assesed with various concentrations of FEX (50, 100, 500, 1000 and 5000 microM) and in the presence of SDS. The FEX transport changed with 10 and 50 microM of SDS and the TEER values, after 120 min, decreased. In conclusion, a low and concentration-dependent permeability was found for FEX across the Caco-2 cells. FEX transport increased and TEER decreased with increasing SDS concentrations. These results supports the use of SDS as anionic surfactant in these concentration; SDS can be used safely as permeation and dissolution enhancer for the oral delivery of FEX.