Mucoadhesive hydrogels for buccal drug delivery
It was the aim of the study to assess in vitro methods for the characterization of mucoadhesive hydrogels for their potential to predict the residence time on human buccal mucosa.
Methods
Mixtures of hydrogels comprising hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (CMC), xanthan gum (XTGM), hyaluronic acid sodium salt (HA), sodium alginate (ALG), carbopol (CP) as well as polycarbophil (PCP) and porcine mucus were analysed for relative rheological synergism. Furthermore, hydrogels were characterized for their texture and mechanical properties. For the assessment of mucoadhesive strength of formulations tensile studies were performed on porcine buccal mucosa. To facilitate a direct comparability of data the residence time of stained hydrogels was determined ex vivo on porcine buccal mucosa and in the oral cavity of volunteers.
Results
The extent of relative rheological synergism was in good agreement with results of in vivo residence time studies. Results from tensile studies were further effected by textural properties of hydrogels leading to a restricted correlation with data from the in vivo experiment. The resistance towards removal by artificial saliva flow ex vivo revealed the highest correlation to the in vivo experiment with increasing mucosal residence time in the rank order CP < HEC, HA, ALG, PCP < CMC < XTGM.
Conclusions
This overview of measurement principles to predict the residence time of hydrogels for buccal application in humans may be a potent tool for the development of semisolid intraoral formulations. Continue here on hydrogels