Effect of carbomer concentration and degree of neutralization on the mucoadhesive properties of polymer films.

Mucoadhesive drug delivery systems may enable a prolonged and localized drug release at various sites of the gastrointestinal tract. In the present study, the mucoadhesive properties of flexible polymeric films based on PVP or PVA as film-forming polymers were assessed by measuring the detachment force from excised porcine duodenal mucosa using a tensile strength tester. The mucoadhesive films were comprised of an impermeable backing layer of cellulose acetate butyrate. Carbopol 934P, Carbopol 974NF, and Noveon AA1 were incorporated as mucoadhesive excipients in concentrations of 0-22 wt% relative to the dry mass of the mucoadhesive layer and with various degrees of neutralization corresponding to pH 4.8, 5.5, 6.8, or 7.5. Films based on PVP were generally more mucoadhesive than corresponding formulations based on PVA. Maximum adhesion of PVP-films was observed at pH 5.5 and 6.8 depending on the type of the mucoadhesive polymer and its concentration. An optimal mucoadhesive polymer concentration range was found to be between 2 and 10 wt%. Higher polymer concentrations did not further enhance the mucoadhesive properties, and in some cases even decreased mucoadhesion. Film formulations based on PVA demonstrated no satisfactory mucoadhesive strength.