Table 2 Metabolic ratio for codeine O-demethylation following administration of a single oral dose to a population of horses of differing breeds and ages. The metabolic ratio calculated as (codeine AUC0 − ∞)/(morphine AUC0 − ∞ + M3G AUC0 − ∞ + M6G AUC0 − ∞)
From: Functional phenotyping of the CYP2D6 probe drug codeine in the horse
Age (years) | Breed | Number | Metabolic ratio | ||
|---|---|---|---|---|---|
Mean ± SD | Median | Range | |||
0–5 | Paint | – | – | – | – |
QH | – | – | – | – | |
SB | – | – | – | – | |
TB | 28 | 0.029 ± 0.029 | 0.019 | 0.002–0.119 | |
WB | 1 | 0.004 ± 0.00 | NA | NA | |
6–10 | Paint | 1 | 0.026 ± 0.00 | NA | NA |
QH | 2 | 0.023 ± 0.027 | 0.023 | 0.004–0.042 | |
SB | 1 | 0.023 ± 0.00 | NA | NA | |
TB | 17 | 0.048 ± 0.038 | 0.037 | 0.012–0.147 | |
WB | 5 | 0.016 ± 0.016 | 0.010 | 0.006–0.045 | |
11–15 | Paint | – | – | – | – |
QH | 7 | 0.019 ± 0.010 | 0.017 | 0.007–0.036 | |
SB | 1 | 0.072 ± 0.00 | NA | NA | |
TB | 7 | 0.021 ± 0.022 | 0.013 | 0.005–0.067 | |
WB | 4 | 0.015 ± 0.012 | 0.011 | 0.005–0.033 | |
16–20 | Paint | – | – | – | – |
QH | 2 | 0.011 ± 0.004 | 0.011 | 0.009–0.014 | |
SB | – | – | – | – | |
TB | 9 | 0.012 ± 0.008 | 0.008 | 0.003–0.017 | |
WB | 2 | 0.012 ± 0.003 | 0.012 | 0.010–0.014 | |
21–25 | Paint | 1 | 0.037 ± 0.00 | NA | NA |
QH | 2 | 0.018 ± 0.005 | 0.018 | 0.014–0.021 | |
SB | 1 | 0.029 ± 0.00 | NA | NA | |
TB | 4 | 0.018 ± 0.007 | 0.019 | 0.009–0.024 | |
WB | 2 | 0.027 ± 0.023 | 0.027 | 0.011–0.044 | |
26–30 | Paint | – | – | – | – |
QH | 1 | 0.032 ± 0.00 | NA | NA | |
SB | 1 | 0.014 ± 0.00 | NA | NA | |
TB | 1 | 0.025 ± 0.00 | NA | NA | |
WB | – | – | – | – | |