## 4 Discussions  
The current UHPLC-MS/MS approach involves separating the required analytes, DVB and EFB, using a mobile phase solution with a constant composition. The resolution operation was performed at 0.5 mL/min for one minute. The calibration curve for the DVB, as estimated utilizing the disclosed approach, showed a linear correlation across the whole range of 1 to 3000 ng/mL.  
The usage of EFB as an IS in the quantification of DVB was implemented following the UHPLC-MS/MS methodology, which depends on three crucial criteria. The protein precipitation extraction technique is proven to be effective in extracting both DVB and EFB targets, yielding 101.28 \(\pm\) 2.84% with an RSD below 2.80% for DVB, and 101.61 \(\pm\) 3.23% with an RSD below 3.18% for EFB. Furthermore, the peaks of DVB (0.43 min) and EFB (0.77 min) were attained in a one-minute timeframe. The aforementioned outcome provides proof of the success of the UHPLC-MS/MS method as a proficient and efficient analytical instrument. The used method not only efficiently decreases the overall period of the  
Figure 8: (**A**) DVB metabolic stability curve; (**B**) the natural logarithm (ln) curve (linear segment) exhibiting the linear regression equation.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Time (min.)** & **Mean a (ng/mL)** & **X b ** & **LN X** & **The Linear Segment Features** \\ \hline
0.00 & 380.45 & 100 & 4.61 & Regression line equation: \\
2.50 & 321.44 & 84.49 & 4.44 & y = \(-0.04479\mathrm{x}+4.563\) \\
5.00 & 279.33 & 73.42 & 4.30 & \\
7.50 & 252.96 & 66.49 & 4.20 & R\({}^{2}\) = 0.9920 \\
15.00 & 195.86 & 51.48 & 3.94 & Slope: \(-0.04479\) \\
20.00 & 143.62 & 37.75 & 3.63 & \\
25.00 & 120.75 & 31.74 & 3.46 & t\({}_{1/2}\): 15.48 min and \\
30.00 & 101.88 & 26.78 & 3.29 & Cl\({}_{\mathrm{int}}\): 52.39 mL/min/kg \\
45.00 & 94.28 & 24.78 & 3.21 & \\
60.00 & 71.30 & 18.74 & 2.93 & \\ \hline \hline \end{tabular}
\end{table}
Table 9: The parameters of dovitnib (DVB) metabolic stability.  
procedure, but also optimizes the utilization of ACN, hence lining up with the principles of sustainable chemistry. Also, it is essential to recognize that the participants in a particular medical setting did not take both substances (DVB and EFB) at the same time. Hence, the UHPLC-MS/MS approach can be applied for pharmacokinetic and TDM experiments on DVB.  
The in silico metabolic lability (0.9995) aligned with the in vitro metabolic stability investigation of DVB with HLMs. The metabolic stability of DVB was determined by applying the UHPLC-MS/MS system following a metabolic incubation experiment with HLMs. The in vitro t\({}_{1/2}\) was 15.48 min. The clearance of DVB was determined to be 52.39 mL/min/kg. Following [PERSON] et al. (2015), DVB is classified as a drug with high clearance in the grading system. This means that it can be given devoid of any doubts about the accumulation of dosages in the human body. Utilizing in silico software, such as simulation and Cloe PK software, can provide vital data about the DVB in vivo pharmacokinetics, thereby uncovering important physiological variables ([PERSON] et al., 2018).  
Following the data derived from the in silico DEREK and WhichP450 softwares, it is proposed that creating small changes to the structure of the aryl piperazine ring and quinolinone moieties, or replacing theses structural alerts in the drug design process, might possibly improve the stability properties and metabolic safety of new derivatives, in comparison to DVB (Figure 9). Modifying the stated part or changing the group in the drug design context can improve the safety profile and metabolic stability of newly developed compounds in comparison to DVB ([PERSON] et al., 2019; [PERSON] et al., 2019).