Table 2.
Effect of grapefruit juice coadministration on the stereoselective pharmacokinetics of amlodipine.
| Pharmacokinetic variable | Enantiomer | Amlodipine + grapefruit juice | Amlodipine + water (control) | Ratio juice/water Point estimate (%) and 95% CI |
|---|---|---|---|---|
| Oral amlodipine | ||||
| AUC(0,24h) (ng ml−1 h) | ||||
| (n = 10) | S(–) | 44.9 ± 8.3 | 42.7 ± 7.3 | 102.9 (96.6, 109.6) |
| R(+) | 41.2 ± 10.6 | 40.9 ± 7.7 | 99.2 (93.1, 105.8) | |
| S/R | 1.08 | 1.04 | 103.7 (99.2, 108.3) | |
| C8 (ng ml−1) | ||||
| (n = 14) | S(–) | 2.7 ± 0.4 | 2.6 ± 0.4 | 103.7 (96.4, 111.5) |
| R(+) | 2.5 ± 0.4 | 2.5 ± 0.5 | 101.1 (94.7, 108.0) | |
| S/R | 1.06 | 1.03 | 102.5 (100.2, 104.9)⋆ | |
| Intravenous amlodipine | ||||
| AUC(0,96h) (ng ml−1 h) | ||||
| (n = 15) | S(–) | 138.9 ± 35.3 | 137.0 ± 37.6 | 100.2 (88.2, 113.8) |
| R(+) | 131.4 ± 33.8 | 133.2 ± 37.6 | 98.1 (86.7, 110.9) | |
| S/R | 1.06 | 1.03 | 102.2 (95.9, 108.8) | |
| Cmax (ng ml−1) | ||||
| (n = 11) | S(–) | 12.4 ± 3.4 | 16.7 ± 6.7 | 74.4 (57.8, 95.6)⋆ |
| R(+) | 13.0 ± 3.6 | 17.2 ± 7.0 | 75.6 (58.8, 97.3)⋆ | |
| S/R | 0.95 | 0.97 | 98.3 (94.4, 102.4) | |
For subjects (n) with complete data for both enantiomers (i.e. after both routes and with both juice and control treatments). S/R ratios are geometric means; all others are arithmetic means ± s.d. C8 is plasma concentration at 8 h after oral dosing
⋆
P < 0.05.