The composition and method of preparation of the sodium deoxycholate gel was taken from a previous work published by Valenta and collaborators . In particular, 0.5% sodium deoxycholate (Na-DOC) was dissolved in phosphate buffer saline (0.1 M phosphate buffer pH 7.2 containing 0.9% sodium chloride) and 5% of mannitol was added. Finally, 0.05% (w/w) CP dissolved in 10% (w/w) PEG-400 was added to Na-DOC Gel with continuous stirring until uniform distribution.