Table 1.
Pharmacokinetic parameters of tylosin (17.5 mg/kg, IM) and tilmicosin (10 mg/kg, SC) in Holstein cows (n = 6) after a single parenteral administration.
| Parameters | Tylosin (mean ± SD) |
Tilmicosin (mean ± SD) |
||
|---|---|---|---|---|
| Serum | Milk | Serum | Milk | |
| C max (µg/mL) | 1.30 ± 0.24 | 4.55 ± 0.23∗ | 0.86 ± 0.20 | 20.16 ± 1.13∗ |
| t max (h) | 2 | 4 | 1 | 8 |
| AUC (µg·h/mL) | 20.95 ± 1.73 | 104.29 ± 12.63∗ | 28.42 ± 8.68 | 639.09 ± 65.33∗ |
| t 1/2ab (HO) (h) | 0.54 ± 0.31 | — | 0.21 ± 0.04 | — |
| α (h−1) | 0.26 ± 0.19 | — | 0.26 ± 0.09 | — |
| β (h−1) | 0.03 ± 0.003 | — | 0.02 ± 0.005 | — |
| t 1/2α (HO) (h) | 2.63 ± 2.50 | — | 2.68 ± 1.10 | — |
| t 1/2β (HO) (h) | 20.46 ± 2.08 | 26.36 ± 5.55∗ | 29.94 ± 6.65 | 43.02 ± 5.18∗ |
| V d (L/kg) | 20 ± 0.9 | — | 15.56 ± 2.95 | — |
| K 01 (h−1) | 1.28 ± 0.57 | — | 3.14 ± 0.54 | — |
| K 12 (h−1) | 0.08 ± 0.07 | — | 0.07 ± 0.04 | — |
| K 21 (h−1) | 0.10 ± 0.05 | — | 0.18 ± 0.04 | — |
| C max-milk/C max-serum | 3.61 ± 0.69 | 20.16 ± 1.13 | ||
| AUCmilk/AUCserum | 5.01 ± 0.72 | 23.91 ± 6.38 | ||
*Values shown in the same row are statistically significant (P < 0.05).
C max: maximum concentration; t max: time to peak concentration; AUC: area under the curve from zero to infinity by the trapezoidal integral; t 1/2ab: absorption half-life; α; distribution rate constant; β: elimination rate constant; t 1/2α: distribution half-life; t 1/2β: elimination half-life; V d; volume of distribution; K 01: first-order elimination rate constant; K 12 and K 21: first-order rate constants for drug distribution between the central and peripheral compartments; HO: harmonic mean, SD: standard deviation.