## 3 Results and Discussion
The presence or absence of pores may be one of the features indicating the differences between bulk erosion and surface erosion. This was shown by [PERSON] and coworkers, who compared the morphological features during the degradation of poly(ethylene carbonate) and PLGA films loaded with rifampicin [67]. In this study, the P(L-LA:GA:TMC) should represent a mixed mechanism at the level of morphological features, _i.e.,_ L-LA and GA are responsible for bulk erosion, and TMC for surface erosion. Previously, P(L-LA:GA:TMC) rods with 17-\(\beta\)-estradiol revealed more features characteristic of surface erosion [40]. This thesis is also supported by [PERSON] and coworkers, who pointed out, after interpreting our results, that surface erosion dominated over bulk erosion [68], whereas for the P(L-LA:GA:TMC) rods with aripiprazole, the presence of pores indicated the dominant role of bulk erosion [46]. It should also be pointed out that the physicochemical properties of drug substances may change their morphological features, thus influencing the main degradation characteristics. In this study, single pores were observed for the EB-P(L-LA:GA:TMC) matrix-LTP on the 15 th, 29 th, and 85 th days of degradation (Figure 5), with circularity values of 0.499, 0.416, and 0.562, respectively (Table 3). Previously, it was shown that for EB-irradiated rods based on P(L-LA:GA:TMC), earlier pore formation resulted in an increase in _WUI_, or vice versa [46]. In turn, [PERSON] and coworkers revealed that the microcavities facilitated the degradation of EB-irradiated PLGA films [66], which may also contribute to pore formation. The presence of oval elements on the 1 st and 57 th days of degradation for the P(L-LA:GA:TMC) matrix-LTP (Figure 4) and on the 71 st day of degradation for the EB-P(L-LA:GA:TMC) matrix-LTP (Figure 5) may also be considered for circularity. However, clear changes in the values of this parameter related to this morphological feature were not noted (Table 3). In a study by [PERSON] and coworkers on poly-\(\epsilon\)-caprolactone nanocapsules with LTP designed for alopecia treatment, morphological analysis performed using SEM revealed predominantly spherical structures on the surface. But the study was only carried out for the native formulation [55]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{5}{c}{**P(L-LA:GA:TMC) Matrix-LTP**} \\ \hline \multirow{2}{*}{**Time (Days)**} & \multirow{2}{*}{**Area (\(\mu\)m\({}^{2}\))**} & \multirow{2}{*}{**Heterogeneity (\%)**} & \multirow{2}{*}{**Circularity**} & \multirow{2}{*}{**Solidity**} \\  & & & & \\ \hline  
The solution casting and EB irradiation processes did not result in unfavorable features, such as disintegration, cracks, microcavities, and slits, which confirmed the ImageJ(r) measurements of solidity. For the native P(l-LA:GA:TMC) matrix-LTP and the native EB-P(l-LA:GA:TMC) matrix-LTP, the values of solidity were 0.81 and 0.83, respectively, where a value of 1.0 means total solidity. The 113 days of degradation influenced the decrease in this parameter to 0.19 and 0.21, respectively, which reflected the increase in morphological diversity. The lack of significant differences in solidity between both matrices during degradation pointed out the lack of unfavorable changes caused by EB irradiation (Table 3). In this study, a controlled and prolonged release of LTP from P(l-LA:GA:TMC) matrix-LTP and EB-P(l-LA:GA:TMC) matrix-LTP over 113 days was achieved (Figure 6), which may enable less frequent administration of the final medicinal product and may improve LTP bioavailability compared to eye drops. Both profiles were characterized by (i) a tri-phasic and sigmoidal pattern; (ii) a lack of burst effect; and (iii) a relatively long second release phase. The release of LTP from P(l-LA:GA:TMC) matrix-LTP and EB-P(l-LA:GA:TMC) matrix-LTP indicated heterogeneous degradation [69; 70].