Table 2.
Inhibition of Ciprofloxacin and Minocycline Transport by Organic Cationsa
| Agent | Ki for ciprofloxacin transportb | Ki for minocycline transportb |
|---|---|---|
| Adenine | 1.36 ± 0.10 mM (competitive) | 1.75 ± 0.12 mM (competitive) |
| Diazepam | No inhibition at 2 mM | 0.89 ± 0.08 mM (competitive) |
| Phenylephrine | 2.66 ± 0.19 mM (noncompetitive) | 1.49 ± 0.14 mM (competitive) |
| Pyrilamine | 6.16 ± 0.45 mM (noncompetitive) | 2.76 ± 0.25 mM (competitive) |
| Papaverine | 1.74 ± 0.12 mM (noncompetitive) | 1.41 ± 0.14 mM (competitive) |
| Tetracycline | 1.76 ± 0.17 mM (noncompetitive) | 2.32 ± 0.14 mM (competitive) |
a
Derived from Lineweaver-Burk analysis of transport activity observed in the presence and absence of the indicated agents.
b
Inhibitory constants are expressed as the mean ± SEM of at least three experiments. The mechanisms of inhibition are included in parentheses.