Gas chromatographic analysis of fosfomycin in plasma for pharmacokinetic analysis

An efficient method for gas chromatographic analysis of fosfomycin in plasma was developed for preliminary investigations of the bioavailability in poultry of 3 commercial complexes of fosfomycin: a levorotatory Ca(-) salt, a racemic Ca(+/-) salt, and a tromethamine (THAM) salt. The method was used to determine whether the less expensive racemic mixture would provide equivalent levels of fosfomycin in blood as the pure Ca(-) form and the THAM salt. The THAM salt, a more expensive product to market, was thought to have the greatest bioavailability. The assay is selective, sensitive, and applicable to pharmacokinetic analysis.