Effects of age on the pharmacokinetics of single dose ceftiofur sodium administered intramuscularly or intravenously to cattle

摘要: The effects of maturation on the intravenous (IV) and intramuscular (IM) pharmacokinetics ceftiofur sodium following a dose 2.2 mg equivalents/kg body weight were evaluated in 16 one-day-old Holstein bull calves (33-53 kg initially; Group 1) 14 six-month-old steers (217-276 2). 1 fed unmedicated milk replacer until 30 days age then converted to same roughag/concentrate diet as 2. Groups 1-IV 2-IV received IV, 1-IM 2-IM IM. dosed at 7 3 months age; group 2 6 9 age. Blood samples obtained serially from each calf, plasma analysed using an HPLC assay that converts all desfuroylceftiofur metabolites acetamide. Cmax values similar calves, no higher younger than older calves. Plasma concentrations remained above 0.150 microgram free acid equivalents/mliter for 72 h 7-day-old but less microgram/mliter within 48 IV or IM injection 6- 9-month-old Intramuscular bioavailability, assessed by comparing model-derived area under curve (AUCmod) age, appeared be complete. After administration, AUCmod 1-month-old (126.92 +/- 21.1 micrograms.h/mliter 135.0 21.6 micrograms.h/mliter, respectively) was significantly larger 3-, (74.0 10.7 61.0 17.7 68.5 12.8 respectively; P < 0.0001). Vd(ss) decreased linearly first life cattle (0.345 0.0616 L/kg, 0.335 0.919 L/kg 0.284 0.0490 = 0.031), indicative decreasing extracellular fluid volume maturing cattle. ClB smaller (0.0178 0.00325 L/h.kg 0.0167 0.00310 L/h.kg, (0.0303 0.0046 0.0398 0.0149 0.0330 0.00552 0.001). This observation may metabolism and/or excretion processes metabolites. approved dosage regimens 1.1-2.2 mg/kg administered once daily up 5 consecutive will provide MIC bovine respiratory disease pathogens longer period time neonatal Peak more mature cattle, highly suggestive peak tissue would