Milk and Blood Pharmacokinetics of Tylosin and Tilmicosin following Parenteral Administrations to Cows

Table 1

Pharmacokinetic parameters of tylosin (17.5 mg/kg, IM) and tilmicosin (10 mg/kg, SC) in Holstein cows () after a single parenteral administration.

Parameters	Tylosin; (mean ± SD)		Tilmicosin; (mean ± SD)
	Serum	Milk	Serum	Milk
(µg/mL)	1.30 ± 0.24	4.55 ± 0.23*	0.86 ± 0.20	20.16 ± 1.13*
(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*
(HO) (h)	0.54 ± 0.31	—	0.21 ± 0.04	—
(h^−1)	0.26 ± 0.19	—	0.26 ± 0.09	—
(h^−1)	0.03 ± 0.003	—	0.02 ± 0.005	—
(HO) (h)	2.63 ± 2.50	—	2.68 ± 1.10	—
(HO) (h)	20.46 ± 2.08	26.36 ± 5.55*	29.94 ± 6.65	43.02 ± 5.18*
(L/kg)	20 ± 0.9	—	15.56 ± 2.95	—
(h^−1)	1.28 ± 0.57	—	3.14 ± 0.54	—
(h^−1)	0.08 ± 0.07	—	0.07 ± 0.04	—
(h^−1)	0.10 ± 0.05	—	0.18 ± 0.04	—
	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 ().
: maximum concentration; : time to peak concentration; AUC: area under the curve from zero to infinity by the trapezoidal integral; : absorption half-life; ; distribution rate constant; : elimination rate constant; : distribution half-life; : elimination half-life; ; volume of distribution; : first-order elimination rate constant; and : first-order rate constants for drug distribution between the central and peripheral compartments; HO: harmonic mean, SD: standard deviation.