Comparison of glucuronidation rates of opioids in membrane preparations from HK293 cells stably expressing rat UGT1.1 and UGT2B1
| Substrate | UGT2B1 pH Optimum | Expressed UGT2B1 | UGT1.1 pH Optimum | Expressed UGT1.1 |
|---|---|---|---|---|
| pmol/min/mg | pmol/min/mg | |||
| Buprenorphine | 7.0 | 565 | 7.0 | 470 ± 80 (4) |
| Norbuprenorphine | 8.0 | 255 | 8.4 | 200 ± 60 (4) |
| Diprenorphine | 8.0 | 160 | 8.0 | 90 ± 10 (4) |
| Naltrexone | 7.0 | 140 | 7.0 | 16 ± 10 (4) |
| 7-Benzylidinenaltrexone | 7.0 | 67 | 7.0 | 18 ± 9 (4) |
| Nalorphine | 8.4 | 9,700 | 7.7 | 30 ± 9 (4) |
| Naloxone | 7.7 | 2,100 | 7.7 | 17 ± 7 (4) |
| Oxymorphone | 7.7 | 915 | 7.7 | 7 ± 1 (3) |
| (−)-Morphine1-a | 8.4 | 11,700 | 8.4 | 9 ± 4 (6) |
| Naltrindole | 7.7 | 39 | 7.7 | 9 ± 4 (4) |
| Naltriben | 7.7 | 16 | 7.7 | 7 ± 1 (3) |
| Levorphanol1-b | 7.7 | 34 | 7.7 | 6 ± 2 (4) |
| Codeine | 7.7 | ND | 7.7 | ND |
Rat UGT1.1 data are the means ± SE of at least three incubations, whereas rat UGT2B1 data are given as the averages of two individual incubations. UDP-GlcUA concentration was 2.0 mM, optimal pH values are given, and substrate concentrations was 0.5 mM unless otherwise noted. ND indicates that glucuronide formation was not detected. (Level of detection was 2 pmol/min/mg).