Stability and physicochemical characterization of novel milk-based oral formulations

Purpose: The purpose of this work was to assess the colloidal stability of novel milk-based formulations. Methods: Milk-based formulations were prepared in situ by adding into milk alkaline- or ethanolic-drug solutions containing an array of drugs namely; ketoprofen, tolfenamic acid, meloxicam, tenoxicam and nimesulide, mefenamic acid, cyclosporine A, danazol and clopidogrel besylate. The produced formulations were characterized by means of dynamic lightscattering, zeta-potential studies, atomic force microscopy, fluorescence spectroscopy, Raman spectroscopy complemented with ab initio calculations and stability studies. Results: The presence of the drugs did not induce significant changes in most cases to the particle size and zeta-potential values of the emulsions pointing to the colloidal stability of these formulations. Raman spectroscopy studies revealed interactions of the drugs and the milk at the intermolecular level. Complementary analysis with ab initio calculations confirmed the experimental observations obtained by Raman spectroscopy. Finally the produced drug containing alkaline/ethanolic solutions exhibited stability over a period of up to 12 months. Conclusions: The current data demonstrate that milk is a promising drug carrier. (C) 2013 Elsevier B. V. All rights reserved.