Table 3.
Statistical Analysis of the Pharmacokinetic Parameters for Caffeine
| 90% CI for the ratio (test:reference) | |||||||
|---|---|---|---|---|---|---|---|
| Parameter (unit) | Treatment | n | Geometric least squares means | Ratio of geometric least squares means (test:reference) | Lower | Upper | p |
| DN AUC0-t (h·ng/mL/mg) | Caffeinated chewing gum (test) Caffeinated beverage (reference) |
15 16 |
172 160 |
1.07 |
1.04 |
1.11 |
|
| DN AUC0-∞ (h·ng/mL/mg) | Caffeinated chewing gum (test) Caffeinated beverage (reference) |
15 16 |
183 168 |
1.09 |
1.05 |
1.13 |
|
| DN Cmax (ng/mL/mg) | Caffeinated chewing gum (test) Caffeinated beverage (reference) |
15 16 |
28.7 25.7 |
1.12 |
1.04 |
1.20 |
|
| tmax (h)a | Caffeinated chewing gum (test) | 15 | 0.67 | ||||
| Caffeinated beverage (reference) | 15 | 0.58 | −0.08 | −0.17 | 0.08 | 0.3308 | |
| ka (h−1)a | Caffeinated chewing gum (test) | 15 | 2.36 | ||||
| Caffeinated beverage (reference) | 15 | 2.60 | 0.33 | −0.36 | 1.15 | 0.3894 | |
One subject was excluded from chewing gum treatment since the quantifiable predose value was >5% of Cmax value. Only paired data were presented and statistically analyzed for tmax and ka. Least-square means and 90% CI are based on a linear mixed-effects model with treatment as a fixed effect and subject as a random effect. The ratio and corresponding confidence limits are back-transformed from the original difference and confidence.
Medians, median of differences, approximate 90% confidence interval and p-value from the Wilcoxon signed-rank test are presented.
DN AUC0-t, dose-normalized area under the concentration–time curve (AUC) from hour 0 to the last measureable concentration; DN AUC0-∞, dose-normalized AUC extrapolated to infinity; DN Cmax, dose-normalized maximum observed concentration; tmax, time of the maximum observed concentration; ka, absorption rate constant; CI, confidence interval; n, number of subjects.