Table 1.
Independent and dependent variables of experimental design evaluated for freeze-dried liposomes development.
| Variable | Level used |
||
|---|---|---|---|
| Low (−1) | Medium (0) | High (+1) | |
| Independent variables | |||
| X1 = PEG proportion (%) | 0 | 2.5 | 5 |
| X2 = Cholesterol concentration (mM) | 5 | 10 | 15 |
| X3 = The cryoprotectant to phospholipids molar ratio | 0 | 2.5 | 5 |
| X4 = The number of extrusions through 100 nm polycarbonate membranes | 1 | 2 | 3 |
| X5 = The freezing conditions prior lyophilization | −80 °C | −20 °C | None |
| Dependent variables (CQAs) | |||
| Y1 = Liposomal size (nm) | |||
| Y2 = Liposomal SIM concentration (µg/ml) Y3 = The encapsulated simvastatin retention (%) | |||
| Y4 = The residual moisture content (%) | |||
| Y5 = The change in the phospholipid’s transition temperature (°C) | |||