Comparison of cefepime pharmacokinetics in neonatal foals and adult dogs

The pharmacokinetics of cefepime, a new fourth generation cephalosporin wit h enhanced antibacterial activity, was examined in neonatal foals and adult dogs. Cefepime was administered intravenously (i.v,) at a dose of 14 mg/kg to five neonatal foals and six adult dogs. Blood samples were collected in both groups of animals and plasma cefepime concentrations measured by reve rse-phase high-performance liquid chromatography (HPLC). Cefepime concentra tions in both groups of animals were described by a two-compartment pharmac okinetic model with elimination half-lives of 1.65 and 1.09 h for the foal and dog, respectively, We tested whether or not pharmacokinetic parameters for cefepime could be scaled across species using principles of allometry. The parameters of elimination half-life (t(1/2)beta), apparent volume of di stribution (VDarea), and systemic clearance (CL) were scaled linearly to bo dy weight on a double logarithmic plot with allometric exponents for body w eight of 0.26, 1.08 and 0.72, respectively. This study further determined d oses for cefepime, a potentially useful antibiotic for neonatal foals and d ogs, from the pharmacokinetic values. An i.v. dose of cefepime estimated fr om this study for treating sensitive bacteria was 11 mg/kg every 8 h for ne onatal foals and 40 mg/kg every 6 h for dogs.