Table 1.
Hygroscopic properties of drugs and excipients.
| Compound | Density (ρ) kg/m3 | Molar mass (M) kg/kmol | Saturated mass fraction (mfsat) b | Saturated mole fraction (χsat) c | Predicted van’t Hoff factor (i) | Hygroscopic parameter isρs/Ms |
|---|---|---|---|---|---|---|
| Water | 997.0 | 18.0 | NA | NA | NA | NA |
| Albuterol sulfate (AS) | 1340. | 576.7 | 0.28 | 0.012 | 2.1d | 4.9 |
| Budesonide (BD) | 1000.a | 430.0 | Not soluble | Not soluble | NA | NA |
| Citric acid (CA) | 1665. | 192.1 | 0.57 | 0.11 | 1.9d | 16.5 |
| Mannitol (MN) | 1489. | 182.0 | 0.15 | 0.018 | 1.0e | 8.2 |
| Sodium Chloride (NaCl) | 2165. | 58.4 | 0.265 | 0.10 | 2.1f | 77.9 |
| Propylene glycol (PG) | 1036. | 76.1 | 1.00 | 1.00 | 1.0d | 13.6 |
a
Approximate value
b
Mass fraction of compound that can be dissolved in liquid water at 25 °C.
c
Mole fraction of compound that can be dissolved in liquid water at 25 °C.
d
Measured in this study.
e
Based on the measurements of Ninni et al. (2000).
f
Based on the correlations of Cinkotai (1971).