Table 4.
Intraindividual variability in caffeine metabolic ratio stratified by sex, oral contraceptive use by women, induction status, and race
| Subjectsa | No. of subjects | CV (%) (mean ± SD) | |
|---|---|---|---|
| C4 h,PX/C4 h,CAF | AUC0–8 h,PX/AUC0–8 h,CAF | ||
| Men | 12 | 19.1 ± 5.7 | 17.1 ± 6.9 |
| Women | 12 | 26.4 ± 16.6 | 23.1 ± 12.4 |
| Women using OCs | 6 | 34.6 ± 19.0 | 30.1 ± 13.2 |
| Women not using OCs | 6 | 18.3 ± 9.1 | 16.2 ± 7.1 |
| Hyperinducers | 15 | 25.8 ± 14.7 | 23.2 ± 11.2 |
| Normal metabolizers | 9 | 17.8 ± 6.2 | 15.1 ± 6.2 |
| White subjects | 16 | 24.3 ± 15.0 | 20.8 ± 12.0 |
| Nonwhite subjects | 8 | 19.8 ± 5.7 | 18.9 ± 6.2 |
| All subjects | 24 | 22.8 ± 12.7 | 20.1 ± 10.3 |
AUC, area under the concentration–time curve; CAF, caffeine; CV, coefficient of variation; OC, oral contraceptive; PX, paraxanthine.
aA significant difference was not detected between subjects when stratified by sex, OC use, induction status, and race.