Intravenous and intramuscular pharmacokinetics of a single-daily dose of disodium-fosfomycin in cattle, administered for 3 days

Pharmacokinetic parameters of fosfomycin in cattle were determined after administration of buffered disodium fosfomycin either intravenously (i.v.) or intramuscularly (i.m.) at a dose of 20 mg/kg/day for 3 days. Calculated concentrations at time zero and maximum serum concentrations were 34.42 and 10.18 mug/mL, respectively. The variables determined, the elimination half-life of the drug remained unchanged during the 3 days ( = 1.33 +/- 0.3 h for the i.v. route and = 2.17 +/- 0.4 h for the i.m. route). Apparent volumes of distribution suggest moderated distribution out of the central compartment (V(darea) = 673 mL +/- 27 mL/kg and V(dss) = 483 +/- 11 mL/kg). Bioavailability after i.m. administration was 74.52%. Considering fosfomycin as a time-dependent antibacterial drug, plasma concentration vs. time profiles obtained in this study, suggest that clinically effective plasma concentrations of fosfomycin could be obtained for up to 8 h following i.v. administration and approximately 10 h after i.m. injection of 20 mg/kg, for susceptible bacteria. In addition to residue studies in milk and edible tissues, a series of clinical assessments, using fosfomycin at 20 mg/kg b.i.d. or t.i.d. are warranted before this antibacterial drug should be considered for use in cattle.