## 2 Materials and Methods
### Preparation of Oral Disintegrating Films  
An aqueous suspension (TPS) of starch and glycerin was prepared with a proportion (weight/volume) of 5% (\(w/v\)) and 1.25% (\(w/v\)), respectively. This blend was homogenized by stirring, and, in turn, was subjected to heating until it reached a temperature of 70 \({}^{\circ}\)C for 10 min. Subsequently, the stirring was increased to 1200 rpm as the gelatinization of the polymer solution was observed. In parallel, a 2% (\(w/v\)) solution of chitosan in 1% glacial acetic acid was prepared. This solution was homogenized using vigorous stirring at room temperature for 30 min, during which time, complete dissolution of the chitosan was observed. Additionally, a third 5% (\(w/v\)) aqueous maltodextrin solution was prepared. This solution was homogenized by stirring at room temperature until the maltodextrin was completely dissolved.  
The films were made according to the solvent-casting method. From the previously prepared solutions, the filmogenic solution is composed by a ratio of 60:20:20 of polymeric solutions of TPS-chitosan-maltodextrin (TPS-CH-M). The resulting film-forming solution was stirred for 10 min at 500 rpm and then subjected to ultrasonic treatment (Elmasonic Easy 120 H) at 27 kHz, 200 W, and 25 \({}^{\circ}\)C for 10 min. To remove air bubbles, the solution was placed under vacuum. The polymer solution was then poured into a cylindrical mold ensuring a height of 0.17 mm. This value was previously tested to formulate a film with a thickness of less than 0.05 mm; in all cases, these actions were carried out according to recommendations found in the literature [1]. The films were subsequently dried in a forced-ventilation oven (Binder, series 14291) at 65 \({}^{\circ}\)C for 3 h. After drying, they were demolded and conditioned at 25 \({}^{\circ}\)C and 50% relative humidity (RH) for 48 h before physical and chemical property evaluation. The thickness of the films was measured at five random points across five samples using a caliper (Fischer Darex, Le Chambon Feugerolles, France, 150 \(\pm\) 0.1 mm). The average thickness formulated was 0.038 \(\pm\) 0.004 mm.  
The same process and polymer proportions used in the preparation of the previously described matrix were applied, with the incorporation of acetaminophen. The drug loading process was determined using a range between 0.025% and 10%, considering homogeneity and film-forming capacity. Various ratios of film-forming solution volume to drug mass were tested: 90:10, 95:5, 97:3, 91:1, 99:5:0.5, 99.75:0.25 (see Figure S1, Supplementary Information). Based on these trials, the selected maximum drug loading was 99.5:0.5. The preparation consisted of adding the model drug, acetaminophen, to the first solution (TPS solution) before heating. The amount added ensured a final film-forming solution containing 0.5% API. The solution was then poured into molds for drying and film formation, achieving a height of 0.17 mm in the cylinder. The films were conditioned for 48 h at 25 \({}^{\circ}\)C and 50% RH before evaluating their physical and chemical properties. Five random measurements were obtained from five API-containing films, yielding an average thickness of 0.044 mm \(\pm\) 0.005 mm. Additionally, the surface pH was measured using a multiparameter pH meter with two channels (Hanna, HI5522). Readings were recorded after placing the ODFs in contact with distilled water at 37 \({}^{\circ}\)C for 30 s. Three repetitions were performed using 10 different films. The average pH value for films containing API was 6.651 \(\pm\) 0.004, while the average pH value for films without acetaminophen was 6.758 \(\pm\) 0.011. No significant differences were observed between the two.