Necessary impurity level to cause 20% bias on Kt estimates from transport studies
Potency of Substrate | Kt/Kia | Necessary Xi Level to Cause Bias in Kt |
|---|---|---|
| Strong (Kt = 5 μM) | ≤1 | Never a concern when Xi ≤ 10% |
| 10 | ≥2.5% | |
| 100 | ≥0.5% | |
| Moderate (Kt = 50 μM) | ≤1 | Never a concern when Xi ≤ 10% |
| 10 | ≥2.5% | |
| 100 | ≥0.25% | |
| 1000 | ≥0.1% | |
| Weak (Kt = 500 μM) | ≤1 | Never a concern when Xi ≤ 10% |
| 10 | >2.5% | |
| 100 | ≥0.25% | |
| 1000 | Trace | |
|
| 10,000 | Trace |
↵ a Kt/Ki reflects the ratio of the “true” affinity constant of the substrate of interest versus the inhibition constant of its impurity.