Pharmacokinetics and tissue and milk disposition of Tilmicosin in sheep after single administrations

Tilmicosin was administered to sheep intravenously and subcutaneously to determine its concentration in blood, tissue and milk and its kinetic behaviour. After a slow intravenous and subcutaneous injection, the serum concentration-time curve indicated a two compartment open model , elimination half-life (t1/2β) of (4·36 ± 0·04) hours. After a subcutaneous injection the peak plasma drug concentration was (22.54 ± 0.62) mg/ml (Cmax) at 0.5h (Tmax) and the drug was rapidly absorbed and slowly eliminated (t1/2β: 5·02 ± 0·08) h. The apparent volume of distribution of tilmicosin was more than (1.89 ± 0.041). Tilmicosin residues found in liver, kidney and tissue after the 14 and 28 day of withdrawal after intravenous and subcutaneous respectively. Tilmicosin was extensively secreted into milk, Tilmicosin was detectable in milk for 5 and 28 days after a single dose intravenous and subcutaneous respectively.