## 3 Results and Discussion
Previously, it was shown that for P(l-LA:GA:TMC) rods with aripiprazole, pore formation may intensify \(WU\)[46]. But, this is not a necessary  
Figure 2: DSC curves of the first (**a**,**c**) and the second heating runs (**b**,**d**) of P(l-LA:GA:TMC) matrix-LTP (**a**,**b**) and EB-P(l-LA:GA:TMC) matrix-LTP (**c**,**d**). phenomenon because evident porous surfaces were not observed for P(l-LA:GA:TMC) rods with 17-\(\beta\)-estradiol [40]. Generally, a decrease in \(M_{n}\) increases the presence of more hydrophilic end groups. In this study, for P(l-LA:GA:TMC) matrix-LTP, the decrease in \(M_{n}\) from 42.2 kDa to 5 kDa between 0 and the 57 th day of hydrolytic degradation influenced the intensive increase in \(W\!U\) from 12.4% to 97.1% between the 57 th and the 113 th days (Figure 3, Table 2). Moreover, [PERSON] and coworkers observed that EB irradiation influenced the additional decrease in \(M_{n}\)[66], which accelerated the increase in \(W\!U\). Therefore, for the EB-P(l-LA:GA:TMC) matrix-LTP, the changes in \(W\!U\) and \(M_{n}\) were more dynamic (Figure 3, Table 2). An intensive increase in \(W\!U\) equal to 35.0% was noted on the 43 rd day. It should be pointed out that the values of \(M_{n}\) at almost every stage of degradation were lower compared to P(l-LA:GA:TMC) matrix-LTP. Moreover, EB irradiation caused smoother changes in \(M_{n}\) (Figure 3, Table 2). Previously, it was pointed out that an increase in \(W\!L\) is direct proof of the degradation process, whereas parameters such as \(T_{m}\), \(T_{g}\), and \(M_{n}\) provided information about structural, morphological, and thermal changes [46]. It should be noted that the change in \(W\!L\) for the EB-P(l-LA:GA:TMC) matrix-LTP was gradual, and it was difficult to indicate a clear effect of EB irradiation (Figure 3, Table 2), which was noted previously for P(l-LA:GA:TMC) rods with aripiprazole [46]. This may be a result of the physicochemical features of the drug substances. In this study, the ImageJ(r) software was used to develop the outer morphology by determining parameters such as heterogeneity, circularity, and solidity for native and degraded matrices. The measurements were performed on the surfaces of the matrices (Figures 4 and 5, Table 3). The degradation period influenced the heterogeneity of P(l-LA:GA:TMC) matrix-LTP and EB-P(l-LA:GA:TMC) matrix-LTP from 16.5% to 81.7% and from 16.8% to 78.7%, respectively (Table 3). This value has grown over time and had a similar course for both matrices. During degradation, the occurrence of different morphological elements was observed: from a solid surface at the beginning to a sponge-like structure through oval elements and single pores (Figures 4 and 5). Figure 3: Changes (%) in molecular weight (\(M_{n}\)), water uptake (\(W\!U\)), and weight loss (\(W\!L\)) during the degradation of P(l-LA:GA:TMC) matrix-LTP and EB-P(l-LA:GA:TMC) matrix-LTP. No evident porous surfaces were observed for the native and degraded P(L-LA:GA:TMC) matrix-LTP and EB-P(L-LA:GA:TMC) matrix-LTP. However, the value of circularity observed during degradation ranged from 0.039 to 0.684 and from 0.036 to 0.719, respectively. It should be noted that a value of 1.0 for circularity means perfect circles, which indicates the presence of pores. In this study, the relatively high value of this parameter for degraded samples without evident porosity resulted from the degradation process. For the native P(L-LA:GA:TMC) matrix-LTP and the native EB-P(L-LA:GA:TMC) matrix-LTP, the values of circularity were 0.039 and 0.036, respectively. During degradation, on the 113 th day, sponge-like structures were observed, which influenced the circularity increase to 0.652 and 0.719 for P(L-LA:GA:TMC) matrix-LTP and EB-P(L-LA:GA:TMC) matrix-LTP, respectively (Figures 4 and 5, Table 3). Figure 4: SEM images showing changes in the surface morphology of P(L-LA:GA:TMC) matrix-LTP during degradation. Figure 5: SEM images showing changes in the surface morphology of EB-P(L-LA:GA:TMC) matrix-LTP during degradation.