Pharmacokinetics of fosfomycin in chickens after a single intravenous dose and tissue levels following chronic oral administration.

This paper describes the pharmacokinetics of fosfomycin following a single i.v. bolus dose (10 mg/kg of body weight) in broiler chickens. Serial blood samples were collected up to 5 h post-administration. Fosfomycin serum concentrations were determined by a microbiological method, using Proteus mirabilis as the test microorganism. The serum concentration versus time curves after i.v. administration followed a biexponential decline. The main pharmacokinetic variables were t1/2 lambda l = 23 min, t1/2 lambda n = 112 min, VDarea = 575 +/- 190 mL/kg and CLb = 3.12 +/- 0.44 mL.min-1.kg-1. Tissue levels of fosfomycin in kidney, liver, lung, muscle, heart, fat, gizzard and serum were also determined after oral chronic administration of the drug in drinking water (150 micrograms/mL). During the oral chronic administration period, high FOS concentrations in serum were maintained (mean 6.1 +/- 1.1 micrograms/mL), but a significant decline over time could be observed (P < 0.05). Fosfomycin was detected in all tissues except muscle, with mean concentrations ranging from 0.63 microgram/g in fat to 13.48 micrograms/g in kidney. Twenty-four hours after the treatment was finished, fosfomycin levels were below the assay detection limit in all tissues tested.