Quality by design approach for fabrication of extended-release buccal films for xerostomia employing hot-melt extrusion technology

The study endeavors the fabrication of extended-release adipic acid (APA) buccal films employing a quality by design (QbD) approach. The films intended for the treatment of xerostomia were developed utilizing hot-melt extrusion technology. The patient-centered quality target product profile was created, and the critical quality attributes were identified accordingly. Three early-stage formulation development trials, complemented by risk assessment aligned the formulation and process parameters with the product quality standards. Employing a D-optimal mixture design, the formulations were systematically optimized by evaluating three formulation variables: amount of the release-controlling polymer Eudragit® (E RSPO), bioadhesive agent Carbopol® (CBP 971P), and pore forming agent polyethylene glycol (PEG 1500) as independent variables, and % APA release in 1, 4 and 8 h as responses. Using design of experiment software (Design-Expert®), a total of 16 experimental runs were computed and extruded using a Thermofisher ScientificTM twin screw extruder. All films exhibited acceptable content uniformity and extended-release profiles with the potential for releasing APA for at least 8 h. Films containing 30% E RSPO, 10% CBP 971P, and 20% PEG 1500 released 88.6% APA in 8 h. Increasing the CBP concentration enhanced adhesiveness and swelling capacities while decreasing E RSPO concentration yielded films with higher mechanical strength. The release kinetics fitted well into Higuchi and Krosmeyer-Peppas models indicating a Fickian diffusion release mechanism.