Affinity values of morphine and analogs in C6μ, CHOκ, and C6δ membranes
Competition binding assays were performed in a buffer containing 50 mM Tris, pH 7.4, using 0.2 nM [3H]diprenorphine as described under Materials and Methods. Values represent the mean ± S.E.M. of three experiments each performed in duplicate.
| Drug | Ki | Selectivity | Index | ||
|---|---|---|---|---|---|
| C6μ | CHOκ | C6δ | |||
| nM | κ/μ | δ/μ | |||
| Hydromorphone | 0.50 ± 0.03 | 12.9 ± 1.40 | 9.08 ± 1.95 | 26 | 18 |
| Fentanyl | 0.71 ± 0.27 | 86.0 ± 24.0 | 51.16 ± 12.98 | 121 | 72 |
| Oxymorphone | 0.98 ± 0.06 | 80.0 ± 25.0 | 84.20 ± 26.19 | 82 | 86 |
| Morphine | 1.70 ± 0.50 | 65.5 ± 22.6 | 104.57 ± 27.18 | 38 | 61 |
| Methadone | 2.90 ± 0.90 | 1427 ± 249 | 358 ± 119 | 493 | 124 |
| Hydrocodone | 32.6 ± 2.19 | 2212 ± 502 | 1238 ± 332 | 68 | 38 |
| Oxycodone | 43.9 ± 7.04 | 5943 ± 671 | 2160 ± 397 | 135 | 49 |
| Heroin | 158 ± 22.0 | 5634 ± 790 | 3895 ± 871 | 37 | 25 |
| Codeine | 727 ± 128 | 25,411 ± 10,015 | 52,207 ± 25,421 | 35 | 72 |