Design of Mucoadhesive Polymeric Films Based on Blends of Poly(acrylic acid) and (Hydroxypropyl)cellulose

Abstract

Mixing of aqueous solutions of poly(acrylic acid) and (hydroxypropyl)cellulose results in formation of hydrogen-bonded interpolymer complexes, which precipitate and do not allow preparation of homogeneous polymeric films by casting. In the present work the effect of pH on the complexation between poly(acrylic acid) and (hydroxypropyl)cellulose in solutions and miscibility of these polymers in solid state has been studied. The pH-induced complexation-miscibility-immiscibility transitions in the polymer mixtures have been observed. The optimal conditions for preparation of homogeneous polymeric films based on blends of these polymers have been found, and the possibility of radiation cross-linking of these materials has been demonstrated. Although the gamma-radiation treatment of solid polymeric blends was found to be inefficient, successful cross-linking was achieved by addition of N,N'-methylenebis(acrylamide). The mucoadhesive potential of both soluble and cross-linked films toward porcine buccal mucosa is evaluated. Soluble films adhered to mucosal tissues undergo dissolution within 30-110 min depending on the polymer ratio in the blend. Cross-linked films are retained on the mucosal surface for 10-40 min and then detach.

Advances in Mucoadhesion and Mucoadhesive Polymers

“…[41] Hydrogels can be synthesized using a number of different approaches including three-dimensional polymerization of hydrophilic monomers [42,43] or cross-linking of ready-made watersoluble polymers. [44,45] To develop a synthetic hydrogel substitute for mucosal tissues suitable as a substrate for evaluating mucoadhesive properties of tablets we have used two approaches: (i) layer-by-layer deposition of hydrogen-bonded interpolymer complexes of poly(acrylic acid) and methylcellulose on the surface of chemically modified glass with subsequent cross-linking of dry multilayered coatings by thermal treatment at 120 8C; [46] and (ii) three-dimensional copolymerization of 2-hydroxyethyl methacrylate with various co-monomers (2-hydroxyethyl acrylate, N-vinylpyrrolidone, sorbitol methacrylate and N-acryloylglucosamine). [47] The first approach has resulted in ultrathin multilayered hydrogel coatings tightly bound to the surface of glass slides, whereas the second one led to bulk hydrogels.…”

“…The time of complete detachment, dissolution or disintegration of a dosage form is then registered as an indication of mucoadhesive strength of the studied formulations and can be compared with the values obtained in experiments with reference mucoadhesive materials. Some other researchers have used different experimental set-ups and experimental conditions for assessing mucoadhesive properties of dosage forms by rotating disc method, [45,50] which makes a direct comparison between the results reported by different research groups rather difficult. Table 1 shows some experimental data recorded for detachment/dissolution of various tablets from porcine stomach mucosa as an example.…”

“…[77,112] Alternatively solution mixtures may be dried on flat surfaces resulting in mucoadhesive polymeric films [45,113] or spray-dried yielding microparticulate formulations. [114] The control of specific interactions between polymers in a common solvent is of paramount importance as insoluble complexes are often formed and it affects the properties of final dosage forms.…”

Investigation of Interpolymer Complexation Between Poly(Vinylcaprolactam) and Poly(Maleic Acid-Alt-Styrene)

“…Fluorescence spectroscopy, with pyrene as probe, is an important tool for the investigation of the conformational transition of polyelectrolytes [13] and polymer complex formation [29][30][31]. The I 3 /I 1 ratio for pyrene solubilized in distilled water is around 0.60-0.64, but pyrene molecules can migrate to a more hydrophobic environment from the solution and the I 3 /I 1 ratio increases.…”

Mucoadhesive Polymers as Enabling Excipients for Oral Mucosal Drug Delivery

“…Being polyanionic, carbomers may complex with cationic and also non-ionic excipients or drugs, thereby modifying their mucoadhesive potential [116,120].…”