## 3 Results and Discussion
### Physical Properties  
Thickness is one of the most important features characterizing the quality of sublingual films, because it can affect their barrier properties (by prolonging disintegration time) as well as mechanical properties. In this study, prepared films were very easily removed from containers after drying. Appropriate thickness for films is considered to be below 0.25 mm [32], the average thickness values of films were between 0.06 and 0.12 mm. As Table 3 shows, incorporation of GFD to sublingual CMC films had a significant effect on their thickness values (\(p<0.05\)): increasing GFD concentration raised thickness values. The low standard deviations of results suggest homogeneousness of films. Our findings correspond with results of [PERSON] et al. ; it was reported in their manuscript that increasing concentration of CMC expanded film thickness, which could be happening due to entrapment of oil particles in film matrix pores [33]. Moreover, [PERSON] [34] reported that addition of vitamin E to CMC films increased film thickness. Disintegration is significantly related to how quickly the drug is exposed to the environment and to drug dissolution rate. This process is slow for hydrophobic drugs [35]. The dashed line at a disintegration time of 180 s represents the maximum time limit, required by the Ph. Eur. for disintegration of orodispersible tablets [25]. Moreover, a higher disintegration rate is an important parameter for sublingual CMC films containing GFD, because the main active ingredients in the films (flavonoid glycosides) are hydrophobic. As presented in Table 3, the higher amount of GFD in sublingual films statistically increased disintegration time in comparison with the control CMC sample. Only the FRG--18 and FRG--21 samples did not fulfil disintegration time requirements of Ph. Eur [25] for orodispersible tablets (\(t\leq 180\) s). These effects can be explained also by CMC swelling on the film surface and irregular diffusion through the film layer of small volume disintegration medium, which results in prolonged disintegration times [36; 37]. Furthermore, it was observed that higher GFD concentrations also significantly increased the thickness of the film. Thicker films resulted in them being more resistant to water penetration than films with reduced thickness, and hence longer disintegration times were observed for the films containing \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample Name** & \begin{tabular}{c} **Tensile Strength** \\ **(MPa)** \\ \end{tabular} & \
\begin{tabular}{c} **Elongation at Break** \\ **(\%)** \\ \end{tabular} &
\begin{tabular}{c} **Young’s Modulus** \\ **(MPa)** \\ \end{tabular} \\ \hline CMC—0 & \(51\pm 3\) & \(3.6\pm 0.2\) & \(3200\pm 11\) \\ FRG—12 & \(46\pm 5\) a & \(4.2\pm 0.3\) d & \(2800\pm 14\) s \\ FRG—15 & \(40\pm 2\) a & \(5.0\pm 0.4\) d & \(2200\pm 13\) g a \\ FRG—18 & \(36\pm 4\) a,b,c & \(5.3\pm 0.5\) d,e & \(1800\pm 15\) g b,k,k \\ FRG—21 & \(30\pm 2\) a,b,c & \(5.9\pm 0.2\) d,c,d & \(1300\pm 16\) g b,k,k \\ \hline \hline \end{tabular} Mean values in the same column with different letters indicate statistically significant differences (ANOVA/ Tukey’s test, \(p<0.05\)). a \(p\leq 0.05\) vs. CMC—0; b \(p\leq 0.05\) vs. FRG—12; c \(p\leq 0.05\) vs. FRG—15; d \(p\leq 0.05\) vs. CMC—0; e \(p\leq 0.05\) vs. FRG—12; f \(p\leq 0.05\) vs. FRG—15; g \(p\leq 0.05\) vs. CMC—0; h \(p\leq 0.05\) vs. FRG—12; k \(p\leq 0.05\) vs. FRG—15; j \(p\leq 0.05\) vs. FRG—15.  
\end{table} 
Table 2: Mechanical properties of sublingual films based on CMC with freeze-dried _G. biloba_ extract (GFD).