Tributyl citrate

Cellulose acetate phthalate (Sigma-Aldrich, St. Louis, MO) and Pluronic F-127 (Sigma-Aldrich) were combined in a 70:30 weight ratio, respectively, for a total mass of 2 g per film. Either tributyl citrate (Sigma-Aldrich) or triethyl citrate (Sigma-Aldrich) was combined with the CAP and PF127 at 0, 10, or 20 wt%. Quercetin (10 or 100 mg; Sigma-Aldrich) or pirfenidone (6.1 or 61 mg; Tokyo Chemical Industries, Portland, OR) was added to the mixture (Figure 1). The low and high loadings of the two drugs are molar equivalents at 0.033 and 0.33 mol. A 25% (w/v) polymer solution was made by adding acetone to the CAP, Pluronic F-127, plasticizer, and drug. Mixtures were vortexed to ensure uniform dissolution of the components, cast into Teflon dishes, and the acetone allowed to evaporate at 10°C overnight. Films were desiccated overnight before analysis. Each sample is subsequently referenced by the average drug loading within individual samples (approximately 64 µg and 640 µg for Quercetin and 39 µg and 390 µg for pirfenidone). The sample calculation below for 100 mg of Quercetin shows how the average loadings were determined.
$$\mathit{\text{Sample Loading}}=\frac{\mathit{\text{Total Film Loading }}\times \mathit{\text{ Area of Sample}}}{\mathit{\text{Area of Total Film}}}$$
$$64\mathrm{\mu }g=\frac{100mg\times \pi {(2.5mm)}^2}{\pi {(31.25mm)}^2}$$