Fabrication and evaluation of a polymeric muco-adhesive film with local and controlled release of phenytoin: an in vitro investigation

Phenytoin has long been used to accelerate wound healing. The aim of this study is to design, fabricate, and evaluate some properties of a polymeric mucoadhesive film with slow release of phenytoin. In this in vitro study, polymers such as Hydroxypropyl Methylcellulose, Sodium carboxymethyl cellulose, Carbopol ® 934, and Polyethylene glycol 400 were used to make the film, and different percentages of Eudragit RS100 were used to achieve the slow release of phenytoin. All materials were obtained in a pharmaceutical grade. The films were made using the solvent casting method. Swelling, degradation, drug release, and muco-adhesion tests were conducted to evaluate the film’s characteristics. Initially, films from formulations F1 (0% Eudragit RS100), F2 (10% Eudragit RS100), and F3 (20% Eudragit RS100) were included in the study due to their homogeneity and suitable appearance characteristics. The swelling test over 2 h showed that the swelling of the F3 formulation (773.00 ± 23.43%) was less than that of the F2 formulation (947.33 ± 58.05%), and the F2 formulation was less than that of the F1 formulation (1572.33 ± 38.00%). The degradation test over 7 days showed that the degradation of the F3 formulation (67.90 ± 1.29%) was less than that of the F2 formulation (78.24 ± 3.14%), and the F2 formulation was less than the F1 formulation (86.89 ± 1.68%). The drug release test over 8 h showed that the release of phenytoin from the F3 formulation (240 min) was slower than the F2 formulation (180 min), and the F2 formulation was slower than the F1 formulation (140 min). All F1, F2, and F3 formulations showed a non-Fickian mechanism of drug release. Difference and Similarity factors calculated based on the dissolution curves demonstrated that all three formulations are different from each other regarding the release pattern. The muco-adhesion test showed that the adhesion of the film containing F3 formulation (4074.07 ± 848.63 N/m²) was significantly higher than that of the F1 formulation (1916.67 ± 194.44 N/m²), but there was no significant difference in adhesion between the F1, F2, F3 formulations. Considering the limitations of the current study, it can be concluded that increasing the concentration of Eudragit RS100 from 0% to 20% can improve the muco-adhesion, sustain the drug release, and decrease the swelling and degradation rate.