The effect of Eudragit RL-100 on the mechanical and mucoadhesion properties of polycarbophil dosage forms

Abstract

Polycarbophil is a high molecular weight acrylic polymer which posses enzymatic inhibition and absorption enhancement properties. However, its use is limited because of poor mechanical properties. In this study Eudragit® RL-100 was tested as a possible regulating agent for polycarbophil solid formulations. Although swelling of polycarbophil-Eudragit® RL-100 films was lower in PBS pH=5.0 than in PBS pH=7.4, in both cases there was a profound difference between the swelling of pure polycarbophil films and films made of mixtures of polycarbophil and increasing amounts of Eudragit® RL-100. Eudragit® RL-100 was able to significantly decrease the swelling of polycarbophil films in a concentration-dependent manner. The incorporation of Eudragit® RL-100 into polycarbophil also affected the mechanical properties of the films, as was evident from the torsion force and modulus of elasticity measurements. The higher the amount of Eudragit® RL-100 in the mixtures with the polycarbophil, the larger the values of torsion force and modulus of elasticity. In the case of tablets made of different ratios of Eudragit® RL-100 and polycarbophil, the larger the amount of Eudragit® RL-100 the higher the rate of erosion of the tablet. Tablets containing predetermined ratios of polycarbophil and Eudragit® RL-100 were able to synchronize the release rate of sodium cefazolin and ibuprofen. It was found that the similarity in the release rates resulted from a controlled erosion process governed by balancing the ratio of Eudragit® RL-100 and polycarbophil. The mucoadhesion properties of polycarbophil-Eudragit® RL-100 tablets with increasing amounts of Eudragit® RL-100 was measured in different regions of the GI tract of the rat. It was found that tablets containing up to 20%w/w of Eudragit® RL-100 adhered significantly better to the cecum of the rat and that their adherence to the stomach, jejunum and colon did not differ from each other. Eudragit® RL-100 concentrations of 50%w/w and above significantly reduced the ability of polycarbophil to adhere to the GI epithelium. Based on the reported findings it is suggested that solid dosage forms made of mixtures of polycarbophil and Eudragit® RL-100 may be suitable for the oral delivery of drugs, such as proteinaceous drugs, susceptible to enzymatic degradation.