Physicochemical characteristics and pH-dependent ionization for six lipophilic amine drugs
Drug | pKa | Log P | Log D7.4 | Percentage Ionization at pH 7.4 | Percentage Un-ionized at pH 7.4 | Percentage Ionization at pH 5.0 | Percentage Un-ionized at pH 5.0 |
|---|---|---|---|---|---|---|---|
| Dextromethorphan | 8.7 | 4.5 | 3.2 | 95.2 | 4.8 | 99.980 | 0.02 |
| Quinine | 8.7 | 3.4 | 2.1 | 95.2 | 4.8 | 99.980 | 0.02 |
| Propranolol | 9.5 | 2.3 | 0.2 | 99.2 | 0.8 | 99.997 | 0.003 |
| Imipramine | 9.5 | 4.0 | 1.9 | 99.2 | 0.8 | 99.997 | 0.003 |
| Fluvoxamine | 9.4 | 3.4 | 1.4 | 99.0 | 1.0 | 99.996 | 0.004 |
| Fluoxetine | 10.1 | 4.2 | 1.5 | 99.8 | 0.2 | 99.999 | 0.001 |