The impact of trimethyl chitosan on in vitro mucoadhesive properties of pectinate beads along different sections of gastrointestinal tract

Pectinate (PEC) beads are multiparticulate dosage forms which have been extensively investigated for oral drug delivery; however their mucoadhesive properties in various sections of GI tract have, not been yet reported. This work, evaluated the in vitro mucoadhesive properties of PEC bead formulations, on rat everted gastrointestinal sections, either with or without trimethyl chitosan (TMC), an absorption-enhancing and fairly mucoadhesive derivative of chitosan. Reference Carbomer 934P (C934P) granules, as an established mucoadhesive polymer, and ethyl cellulose (EC)-coated pellets, as a nonmucoadhesive dosage form, were also used for comparison. Water uptake studies were also performed to further explain the effect of hydration on mucoadhesive properties. PEC beads showed mucoadhesion, which was in some cases comparable to C934P granules, towards the gastrointestinal tissues with following ranking: duodenum approximate to jejunum approximate to ileum > cecum > colon > stomach. In the dry state, the beads containing TMC were more mucoadhesive, while in the moist state simple PEC beads were shown to be more mucoadhesive. Over-hydration of TMC-containing beads may account for this observation. The results of this study suggest that in cases which prehydration can be avoided, such as when the beads are protected in a site-specific oral capsule, prior to reaching the target tissue, the incorporation of TMC into beads might be useful, as a means of increasing the mucoadhesive properties; However, further studies are needed to clarify their in vivo feasibility.