Process of Mucoadhesive Polymer-mucus

Mucoadhesive formulations have been of great interest in recent years. Oneapproach to study mucoadhesion is the technique of dynamic oscillatory rhe-ology (DOR). In this study the use of an extended frequency sweep DOR, instead of the routine limited DOR studies, as a more comprehensive and realistic means of investigating the process of mucoadhesion was investigated. For this pur-pose polymeric discs were directly placed in contact with natural mucus samples and incubated for various time intervals (15, 60 and 120 min) at 37°C, and then they were rheologically examined across a frequency of 0.0001-10 Hz. Results showed that in the presence of anionic mucoadhesive discs containing Carbopol 934P (C934) and sodium carboxymethyl cellulose (NaCMC), the G ' (storage modulus) and to a small-er extent G " (loss modulus) values of the weakly viscoelastic mucus samples are strengthened much more than the non-ionic polymer hydroxypropyl cellulose and the calcium containing Carbopol EX83, and far less reduced at frequencies below 1Hz. However, in the presence of potassium thiocyanate (hydrogen-bond breaking agent), unlike G " values, the G ' values of particularly the anionic polymers C934 and NaCMC suffered a sharp decline at frequencies below 1Hz. These findings support the theo-ry of mucoadhesive polymer chain interpenetration and formation of hydrogen-bonds with the mucus gel network, and shows that by using an extended frequency sweep rather than a normal limited frequency sweep, a more detailed and realistic approach for studying the process of mucoadhesion and putative mucoadhesive polymers and formulations, could be provided