Table 2. Inhibition Concentration 50% (IC50; μM) for Various Opioids Measured Using Competition ELISAa.
| mice
antibody IC50 |
rat antibody IC50 | ||
|---|---|---|---|
| TT-3 + ALF | TT-1 + ALFb | TT-1 + ALFb | |
| Heroin and Its Metabolites | |||
| heroin | >1000 | 1.27 ± 0.3*** | 3.0 ± 0.6*** |
| 6-AM | 104.4 ± 14.8 | 3.72 ± 0.7*** | 1.5 ± 0.6*** |
| morphine | 24.3 ± 4.5 | 2.36 ± 0.6*** | 7.1 ± 2.7* |
| M-3G | >1000 | 28.0 ± 11.4*** | 35.5 ± 14.7*** |
| M-6G | 411.0 ± 94.4 | 25.0 ± 12.1** | 104.4 ± 46.6 |
| normorphine | 19.7 ± 2.5 | 112.43 ± 22.3 | 192.9 ± 57.1 |
| Drugs Used for Opioid Abuse Therapy | |||
| methadone | >1000 | >1000 | >1000 |
| buprenorphine | >1000 | >1000 | >1000 |
| naloxone | >1000 | >1000 | >1000 |
| naltrexone | >1000 | >1000 | >1000 |
| Other Abused Prescription Opioid Drugs | |||
| codeine | >1000 | 3.80 ± 1.3*** | 17.2 ± 5.4*** |
| oxycodone | >1000 | 534.6 ± 79.5*** | 144.6 ± 60.6*** |
| hydrocodone | >1000 | 5.1 ± 1.5*** | 14.7 ± 2.7*** |
| oxymorphone | 110.4 ± 24.5 | 125.5 ± 28.6 | 217.1 ± 94.8 |
| hydromorphone | 59.7 ± 19.2 | 3.6 ± 0.8* | 23.8 ± 8.8 |
| levorphanol | 9.7 ± 4.8 | 3.4 ± 0.9 | 53.6 ± 28.1 |
| meperidine | >1000 | 523.9 ± 143.3* | >1000 |
| tramadol | >1000 | >1000 | >1000 |
| fentanyl | >1000 | >1000 | >1000 |
| sufentanil | >1000 | >1000 | >1000 |
| nalbuphine | >1000 | >1000 | >1000 |
a
Values denote IC50 for the indicated drugs (μM; mean ± SEM) measured using competition ELISA from individual animal sera for each group using triplicate measurements. IC50 was defined as the drug concentration that produced 50% inhibition of maximal antibody and hapten binding as calculated from normalized competition curves using log(inhibitor) vs normalized response-variable slope regression.
b
Asterisks indicate groups with significantly lower IC50 (higher affinity) as compared to the mice group immunized with TT-3 (***, p < 0.0001; **, p < 0.001; *, p < 0.01) using multiple t test with Holm–Šídák correction.