Table 3.
Retention factors and binding constants measured for various drugs on columns containing entrapped AGP or HSA
| Drug | Protein | (Specific retention factor)/(protein content)a | Estimated Ka or nKa′ (M−1) | Literature value (M−1)b |
|---|---|---|---|---|
| Amitriptyline | AGP | 5.66 (± 0.06) | 7.1 (± 0.3) × 105 | 3.4 × 105 (37 °C) [51] 5.3 × 105 (25 °C) [52] |
| HSA | 0.45(± 0.04) | 5.6 (± 0.2) × 104 | 2.12–6.22 × 104 [53] | |
| Chloramphenicol | AGP | 0.015 (± 0.007) | 1.9 (± 0.5) × 103 | Not reported |
| HSA | 0.018 (± 0.006) | 1.6 (± 0.5) × 103 | 8.2 × 103 [54] | |
| Chlorpromazine | AGP | 12.19 (± 0.05) | 1.5 (± 0.4) × 106 | 1 × 106 [55,56] |
| HSA | 0.9 (± 0.1) | 1.2 (± 0.2) × 105 | 1.68–3.3 × 105 (20 °C) 3.46–4.33 × 105 (28 °C) [57] |
|
| Nortriptyline | AGP | 5.91 (± 0.06) | 7.4 (± 0.2) × 105 | 6.7 × 105 [5,58] |
| HSA | 0.50 (± 0.05) | 6.2 (± 0.3) × 104 | 1.81 × 104 [59] | |
| Quinidine | AGP | 2.40 (± 0.05) | 3.0 (± 0.3) × 105 | 2.9 × 105 [60] |
| HSA | 0.17 (± 0.03) | 2.1 (± 0.4) × 104 | 7.7 × 103 (25 °C) [61] 4.78 × 104 (37 °C) [62] |
Each value in parentheses represents a range of ± 1 S.D., as based on triplicate measurements made over five flow rates (n = 15). The normalized retention factors were calculated by dividing the specific retention factors by the total protein content for each given support, as measured in triplicate and using a value of 21 (± 1) mg AGP/g silica or 37 (± 1) mg HSA/g silica. The specific retention factor was obtained by taking the difference between the overall retention factor on an entrapped protein column and the retention factor due to non-specific interactions for the same solute on the control column, with the latter values being as follows: amitriptyline, 71.7 (± 0.5); chloramphenicol, 0.67 (± 0.02); chlorpromazine, 177 (± 3); nortryptyline, 62.5 (± 0.1); and quinidine, 28.3 (± 0.2).
Most of the literature values were determined at pH 7.4 and 37°C [51,53–56,59,62]. The values from Refs. [52,61] were measured at pH 7.4 and 25 °C. The values of 3.46–4.33 × 105 M−1 from Ref. [57] were measured at pH 7.4 and 28 °C, while the values of 1.68–3.3 × 105 M−1 from the same reference were measured at pH 7.4 and 20 °C. The pH and temperature were not provided in Refs. [5,58,60].