Mucoadhesive properties of polyacrylates: Structure – function relationship

Abstract Aim The objective of this study was to evaluate and compare the mucoadhesive properties of ten commercially available polyacrylates including linear polyacrylic acid of 100 and 450 kDa (PAA 100 and 450), with allyl pentaerythritol, allyl sucrose and divinyl glycol cross-linked PAAs (PAA AP, PAA AS/AP, PAA DG) as well as hydrophobically modified cross-linked PAAs (PAA C10-30). Methods Swelling behavior, rheological measurements of polymer/mucus mixtures, rotating cylinder studies and tensile studies were performed to evaluate the mucoadhesive properties of PAAs on intestinal, vaginal and buccal mucosa. Results Investigations on the swelling behavior revealed that higher degree of cross-linking of PAA and higher degree of alkylation of acrylates/C10-30 alkyl acrylate crosspolymers cause a more pronounced swelling following the rank order: PAA C10-30 high > PAA C10-30 medium > PAA C10-30 low > PAA AP high > PAA AP low > PAA AS/AP > PAA DG > PAA C10-30 very low > PAA 450 > PAA 100. The rank order of dynamic viscosity of polymer/mucus mixtures was PAA C10-30 medium > PAA C10-30 low > PAA C10-30 very low > PAA AP high > PAA C10-30 high > PAA AS/AP > PAA DG > PAA AP low > PAA 450 > PAA 100. Rotating cylinder studies and tensile studies showed that mucoadhesive properties of all tested polymers depended on the type of porcine mucosa and the simulated biological buffer. The experiments on various mucosae showed the highest mucoadhesion of PAA AP high, PAA C10-30 low and PAA C10-30 medium. In contrast, the weakest mucoadhesion was attributed to linear PAA 100 and 450 and PAA C10-30 very low. Conclusion Within this study, the mucoadhesive properties of ten different types of polyacrylates were compared with each other facilitating the decision-making for formulation scientists when developing oral, buccal or vaginal mucoadhesive drug delivery systems.