## 3 Results and Discussion  
### Moisture Content and Flowability  
All raw materials have been analysed for their moisture content and flowability (Table 1). Moisture content corresponds to the amount of non-essential water contained in a dry substance. This determination is important to be carried out on components for pharmaceutical use, since water can influence the resulting products at various levels, namely the mixture homogeneity, and stability of the resulting solid pharmaceutical form. Although there is no maximum moisture content limit for solid ingredients (powders), it is desirable that it be less than 8%, in order to minimise particle agglomeration and other problems during the manufacturing of solid dosage forms [28]. An inadequate moisture content of the powders to be mixed may result in problems of homogeneity of the mixture and instability of the resulting solid dosage form. Powders with an excessive moisture content have particles that agglomerate more easily, resulting in changes in the dissolution profile and forming non-resistant solid dosage forms (i.e., more friable, and less resistant to rupture). These impacts may result in changes in the technological ability and stability during the storage period of the pharmaceutical product [29]. The studied components' moisture contents were shown to range from 2.58 to 15.70%. In the case of both esomeprazole Mg, these values (2.58 \(\pm\) 0.1% and 2.97 \(\pm\) 0.09%) indicated the contribution of adsorbed and hydration water, and the wetting water in the other ingredients. Results obtained by loss on drying differed from those obtained by thermal analysis and reported in the manufacturer's analytical certificate in the cases of MCC and both forms of esomeprazole Mg. However, these results are in good agreement with the first mass change determined by thermal analysis. In the case of esomeprazole, these differences are due to the temperature used in the loss on drying method (105 \({}^{\circ}\)C), which is lower than the dehydration temperatures (approximately 130 \({}^{\circ}\)C to 160 \({}^{\circ}\)C). [PERSON] [30] noted that differences are explained by the atmosphere in which the analysis was performed. In the case of loss on drying, analysis was performed at a normal environment (relative humidity over 60%). On the other hand, thermal analysis were performed under nitrogen, being the sample stabilised for a few minutes before starting the temperature program. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Moisture Content (\%)** & **TGA 1 st Mass Change (\%)** & **CInd (\%)** & **CI (\%)** & **HR** \\ \hline MCC & 8.00 \(\pm\) 0.16 & \textless{}2.00 & 22.0 \(\pm\) 1.3 & 21.8 \(\pm\) 1.3 & 1.18 \(\pm\) 0.03 \\ PVP K17 & 14.20 \(\pm\) 0.28 & 12.36 & 16.3 \(\pm\) 1.0 & 16.5 \(\pm\) 1.2 & 1.15 \(\pm\) 0.03 \\ PVP K25 & 15.70 \(\pm\) 0.31 & 16.78 & 21.0 \(\pm\) 1.2 & 21.0 \(\pm\) 1.3 & 1.17 \(\pm\) 0.02 \\ PVP K90 & 13.83 \(\pm\) 0.22 & 12.25 & 17.0 \(\pm\) 1.0 & 17.1 \(\pm\) 1.2 & 1.09 \(\pm\) 0.02 \\ PVA Mw30 & 5.30 \(\pm\) 0.12 & 4.87 & 17.7 \(\pm\) 1.1 & 17.2 \(\pm\) 1.2 & 1.11 \(\pm\) 0.03 \\ Esomeprazole Mg (2H\({}_{2}\)O) & 2.58 \(\pm\) 0.10 & 5.19 & 23.4 \(\pm\) 1.6 & 24.3 \(\pm\) 1.3 & 1.26 \(\pm\) 0.04 \\ Esomeprazole Mg (3H\({}_{2}\)O) & 2.97 \(\pm\) 0.09 & 7.73 & 20.0 \(\pm\) 1.5 & 20.1 \(\pm\) 1.3 & 1.21 \(\pm\) 0.03 \\ Ondanestron & 10.29 \(\pm\) 0.22 & 9.59 & 17.0 \(\pm\) 1.4 & 17.0 \(\pm\) 1.2 & 1.11 \(\pm\) 0.04 \\ \hline \hline \end{tabular} Abbreviations: CI (%)—Carr index; CInd (%)—compressibility index; esomeprazole Mg (2H\({}_{2}\)O)—esomeprazole magnesium dihydrate; esomeprazole Mg (3H\({}_{2}\)O)—esomeprazole magnesium trihydrate; HR—Hausner ratio. MCC—microcrystalline cellulose; PVA—polyvinyl alcohol; PVP—polyvinylpyrrolidone; TGA—thermogravimetric analysis.  
\end{table} 
Table 1: Results obtained for the moisture content (loss on drying and thermal analysis) and flowability properties.