Age-related intramuscular pharmacokinetics of cefquinome in sheep

The pharmacokinetic profile of cefquinome was studied in one, six-months and one year old sheep following a single intramuscular doses of 1 and 10 mg kg−1 b.wt. Cefquinome concentrations in serum were determined by microbiological assay technique using Micrococcus luteus (ATCC 9341) as test organism. Following intramuscular administration of cefquinome, the absorption half-lives (t0.5(ab)) were 1.540, 1.037 and 0.664 h at a dose of 1 mg kg−1 b.wt. and 1.844, 1.290 and 1.605 h at a dose of 10 mg kg−1 b.wt. in the three ages, respectively. After the two doses, the maximum serum concentrations (Cmax) of 0.732, 1.145, 1.205 and 3.525, 5.088, 4.576 μg ml−1 were attained after (tmax) of 3.812, 3.029, 2.174 and 3.785, 2.824, 3.095 h in the three ages, respectively. The elimination half-life (t0.5(el)) and MRT values of cefquinome were longer in one-month old sheep compared to six-months old and yearling sheep. The absorption and elimination processes were delayed in newborn sheep of one-month old in contrary to six-month and yearling animals. The in vitro serum protein-binding tendencies were 8.254%, 11.586% and 13.002%, for one, six-months and one year old sheep, respectively. Based on this study and economically, an optimal intramuscular dosage regimen of cefquinome would be 1 mg kg−1 once daily in one-month, six-months and one-year old sheep to achieve and maintain the therapeutic serum levels within safe limits.