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 mu g/mL, respectively. The variables determined, the elimination half-life of the drug remained unchanged during the 3 days (t(1/2 beta)= 1.33 +/- 0.3 h for the i. v. route and t(1/2)beta=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.