## 3 Results and Discussion  
In this study, the P(L-LA:GA:TMC) terpolymer with a monomer composition of 64.7:17.3:18.0, a \(T_{g}\) of 36.1 \({}^{\circ}\)C, and an \(M_{n}\) of 59.4 kDa (Table 1) was synthesized in the presence of Zr(Acac)\({}_{4}\) as a low-toxicity initiator [45; 49; 50]. Previous studies revealed that P(L-LA:GA:TMC) terpolymers with analogous features ensured the possibility of formulating wafers by solution casting and rods by hot melt extrusion [40; 45; 46]. The \(T_{g}\) was close to the human body temperature, which may ensure the release of the drug substance without a long lag phase. Moreover, the DSC analysis did not reveal endotherms during the first heating run for the raw terpolymer (Table 1), which may suggest an amorphous state and higher bioavailability compared to the semi-crystalline material [44]. In this study, the synthesis conditions ensured that the \(M_{n}\) was suitable for further processing. This is an important feature because of the risk of it decreasing during formulation [45; 51; 52]. The matrices were designed as a universal and appropriate model for the preliminary study of ophthalmic topical solid formulations such as an insert, shield, minidisc, plug, or implant (_e.g._, rod or bead) that releases drugs peripherally. Solution casting was applied as the method of choice due to the following factors: (i) the low processing temperature; (ii) the possibility of combining the liquid drug substance with the solid drug carrier; (iii) high loading efficiency; and (iv) the relatively low \(M_{n}\) decrease in the polymer after formulation. It should be noted that LTP possesses low thermal stability, which was one of the clues for the exclusion of formulation methods using thermal processing. [PERSON] and coworkers revealed that LTP remained stable both at 4 \({}^{\circ}\)C and 25 \({}^{\circ}\)C [53]. In this study, solution casting also allowed liquid LTP and P(L-LA:GA:TMC) \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{5}{c}{**Raw P(L-LA:GA:TMC)**} \\ \hline \(F_{LL}\) & \(F_{GG}\) & \(F_{TMC}\) & \(T_{m}\) & \(T_{g}\) & \(M_{n}\) & \\ (mol\%) & (mol\%) & (mol\%) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (kDa) & \(D\) \\ \hline
64.7 & 17.3 & 18.0 & \(ND\) & 36.1 & 59.4 & 2.241 \\ \hline \hline \end{tabular} \(F_{LL}\), \(F_{GG}\), \(F_{TMC}\)—normal percentage of lacidlyl, glycolidyl, and carbonate units in the terpolymer, respectively, \(T_{m}\)—melting temperature, \(T_{g}\)—glass transition temperature, \(M_{n}\)—molecular weight, \(D\)—molecular weight distribution, and \(ND\)—non-detected.  
\end{table} 
Table 1: Parameters characterizing raw P(L-LA:GA:TMC). to be combined at 25 \({}^{\circ}\)C with 95% efficiency loading of the drug substance determined by \({}^{1}\)H NMR spectroscopy, which was satisfactory and more predictable compared to other formulation methods, for which differences were observed. For example, [PERSON] and coworkers in a study on iontophoretic ocular delivery of LTP from PLGA (50:50) nanoparticles achieved an encapsulation efficiency ranging from 21% to 31% using oil-in-water emulsification [54], whereas [PERSON] and coworkers, for poly-\(\varepsilon\)-caprolactone nanocapsules with LTP designed for alopecia treatment, achieved a much higher efficiency of encapsulation with nanoprecipitation equal to ~94% [55]. Generally, the formulation processes influence the changes in parameters, such as \(T_{g}\) and \(M_{n}\), especially for thermal-dependent formulation methods [45, 51, 52]. In this study, the second heating run for the native P(l-LA:GA:TMC) matrix-LTP revealed an increase in the \(T_{g}\) from 36.1 \({}^{\circ}\)C to 39.9 \({}^{\circ}\)C compared to that of the raw P(l-LA:GA:TMC) (Tables 1 and 2), which can be interpreted as anti-plasticization. This phenomenon, as a result of the introduction of a drug substance into a polymer matrix, was also observed previously, _i.e._, for l-PLGA with isperidone and poly(d,l-lactide-\(co\)-glycolide) or d,l-PLA with leuprorelin [44, 56].